doctor of philosophy in agriculture...

INFLUENCE OF FRUIT THINNING INTENSITY, CALCIUM AND

GIBBRELLIC ACID APPLICATION ON FRUIT YIELD AND

QUALITY OF PEACH

By

SYED TANVEER SHAH

A dissertation submitted to the University of Agriculture Peshawar in partial

fulfillment of the requirements for the Degree of

DOCTOR OF PHILOSOPHY IN AGRICULTURE

(HORTICULTURE)

DEPARTMENT OF HORTICULTURE

FACULTY OF CROP PRODUCTION SCIENCES

THE UNIVERSITY OF AGRICULTURE

PESHAWAR PAKISTAN

JANUARY, 2017


GIBBRELLIC ACID APPLICATION ON FRUIT YIELD AND

QUALITY OF PEACH

BY

SYED TANVEER SHAH

A dissertation submitted to the University of Agriculture, Peshawar in partial

fulfillment of the requirements for the Degree of

DOCTOR OF PHILOSOPHY IN AGRICULTURE

(HORTICULTURE)

Approved by:

_____________________________ Chairman Supervisory Committee

Dr. Muhammad Sajid

Associate Professor

_____________________________ Member (Major Field)

Prof. Dr. AbdurRab

_____________________________ Member (Minor Field)

Prof. Dr. Muhammad Arif

Department of Agronomy

_____________________________ Chairman & Convener

Prof. Dr. Noor ul Amin Board of Studies

_____________________________ Dean

Prof. Dr. Muhammad Jamal Khan Faculty of Crop Production

_____________________________ Director Advance Studies and Research

Prof. Dr. Muhammad Jamal Khan

DEPARTMENT OF HORTICULTURE

FACULTY OF CROP PRODUCTION SCIENCES

THE UNIVERSITY OF AGRICULTURE

PESHAWAR-PAKISTAN

JANUARY, 2017

Dedication

Every challenging work needs self efforts as well as guidance of elders

especially those who were very close to my heart.

My humble effort, I dedicate this Dissertation to my sweet and loving

Father and Mother,

Whose affection, love, encouragement and prays of day and night make me

able to get such success and honor,

Along with my loving

Sister and Brother

Last but not the least to my sweet little Angel

ZARGHUNA

SYED TANVEER SHAH

i

TABLE OF CONTENTS

Title Page No.

LIST OF TABLES .......................................................................................................... i

LIST OF FIGURES ....................................................................................................... ii

LIST OF APPENDICES ............................................................................................... iv

LIST OF ABBREVIATIONS ...................................................................................... vii

ACKNOWLEDGEMENT ......................................................................................... viii

THESIS ABSTRACT .................................................................................................... 1

CHAPTER I ................................................................................................................... 3

GENERAL INTRODUCTION ...................................................................................... 3

CHAPTER II ................................................................................................................ 13

REVIEW OF LITERATURE ....................................................................................... 13

CHAPTER III .............................................................................................................. 21

EFFECT OF THINNING INTENSITY AND TIMINGS ON QUALITY FRUIT

YIELD OF PEACH ..................................................................................................... 21

ABSTRACT ............................................................................................................. 21

INTRODUCTION ................................................................................................... 22

MATERIALS AND METHODS ............................................................................. 23

RESULTS ................................................................................................................. 26

DISCUSSION .......................................................................................................... 36

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS ............................. 47

CHAPTER IV .............................................................................................................. 49

INFLUENCE OF IRRIGATION INTERVALS AND GIBBRELLIC ACID ON SPLIT

PIT INCIDENCE AND FRUIT QUALITY OF PEACH ............................................ 49

ABSTRACT ............................................................................................................. 49

INTRODUCTION ................................................................................................... 50


RESULTS ................................................................................................................. 55

DISCUSSION .......................................................................................................... 60


CHAPTER V ............................................................................................................... 70

EFFECT OF CALCIUM SOURCES AND CONCENTRATIONS ON THE

QUALITY AND STORAGE PERFORMANCE OF PEACH .................................... 70

ABSTRACT ............................................................................................................. 70

INTRODUCTION ................................................................................................... 71


RESULTS ................................................................................................................. 77

DISCUSSION .......................................................................................................... 92


CHAPTER VI ............................................................................................................ 102

EFFECT OF 1-METHYLCYCLOPROPENE (1-MCP) CONCENTRATIONS ON

STORABILITY OF PEACH FRUIT CV. EARLY GRAND ..................................... 102

ii

ABSTRACT ........................................................................................................... 102

INTRODUCTION ................................................................................................. 103

MATERIALS AND METHODS ........................................................................... 105

RESULTS ............................................................................................................... 108

DISCUSSION ........................................................................................................ 122

OVER ALL CONCLUSIONS AND RECOMMENDATIONS............................. 131

LITERATURE CITED............................................................................................... 133

APPENDICES ........................................................................................................... 179

_____________________________________________________________________

i

LIST OF TABLES

Table No. Title Page No.

Table 3. 1: Fruit weight (g), fruit volume (cm3), fruit per kg, fruit yield tree

-1 (kg) and

split pit incidence (%) of peach fruits as affected by thinning intensity and

time. .......................................................................................................... 29

Table 3. 2: Fruit firmness (kg cm-2

), total soluble solids (°brix), percent acidity, ....... 34

Table 4. 1: Leaf area (cm2) of peach as affected by irrigation intervals and gibbrellic

acid concentrations (ppm). ....................................................................... 55

Table 4. 2: Fruit weight (g), fruit volume (cm3), number of fruits kg

-1 and fruit yield

tree-1

(kg) of peach as affected by gibbrellic acid concentration and

irrigation intervals. ................................................................................... 57

Table 4. 3: Split pits incidence (%), fruit firmness (kg cm-2

) and total soluble solids

(°brix) of peach as affected by gibbrellic acid concentration and irrigation

intervals. ................................................................................................... 59

Table 5. 1: Firmness (kg.cm-2

), TSS (°brix), percent acidity (%) and TSS-acid

ratio of peach as affected by calcium sources and concentration during

storage ………………………………………………………………...80

Table 5. 2: Ascorbic acid (mg 100g-1

), reducing sugars (%) and non reducing

sugars (%) of peach as affected by calcium sources and concentration

during storage…………………………………………………………... 84

Table 5. 3: Brown rot incidence (%), Fruit calcium content (%), Cell wall and cell

membrane ion leakage (%) of peach as affected by calcium sources and

concentration during storage .................................................................... 89

Table 6. 1: Fruit firmness (kg.cm-2

), TSS (0brix), Percent acidity (%), TSS-acid ratio

and ascorbic acid (mg.100g-1

) of peach fruit as affected by 1-MCP levels

during storage. ........................................................................................ 110

Table 6. 2: Reducing sugars (%), non reducing sugars (%), weight loss (%) and fruit

decay (%) of peach as affected by 1-MCP levels during storage ........... 114

Table 6. 3: Free radical scavenging activity (FRSA) (%), catalase activity (U g-1

protein), total phenols (mg GAE 100 g-1

), antioxidant activity (mg kg-1

) of

peach as affected by 1-MCP levels during storage ................................. 119

ii

LIST OF FIGURES

Figure No. Title Page No.

Fig 3. 1: Fruit weight (g) as affected by interactive effect of thinning intensity and

time………………………………………………………………………..30

Fig 3. 2: Fruit yield tree-1

(kg) as affected by interactive effect of thinning intensity

and time……………………………………………………………………30

Fig 3. 3: Split pits incidence (%) of peach as affected by the interactive effect of

thinning intensity and time………………………………………………..31

Fig 3. 4: Fruit firmness of peach as affected by the interactive effect of thinning

intensity and time…………………………………………………………35

Fig 3.5: Ascorbic acid (mg 100g-1

) of peach as affected by the interactive effect of

thinning intensity and time………………………………………………..35

Fig 5.1 Interactive effect of Ca. sources and concentrations on fruit firmness (kg.cm-2

)

of peach……………………………………………………………………81

Fig 5. 2: Interactive effect of Ca. concentrations and storage duration on fruit firmness

(kg.cm-2

) of peach ........................................................................................ 81

Fig 5.3: Interactive effect of Ca. sources and concentrations on total soluble solids

(°brix) of peach ............................................................................................ 82

Fig 5.4: Interactive effect of Ca. sources and concentrations on Brown rot incidence

(%) of peach ................................................................................................ 90

Fig 5. 5: Interactive effect of Ca. sources and concentrations on weight loss (%) of

peach ............................................................................................................ 90

Fig 5.6: Interactive effect of Ca. sources and concentrations on fruit calcium content

(%) of peach ................................................................................................ 91

Fig 6.1: Effect of 1-MCP and storage duration Interaction on fruit firmness (kg cm-2

)

of peach ..................................................................................................... 111

Fig 6.2: Effect of 1-MCP and storage duration Interaction on ascorbic acid (mg 100g-1

)

of peach ……………………………………………………………….111

Fig 6. 3: Effect of 1-MCP and storage duration interaction on reducing sugars (%) of

peach fruits ................................................................................................ 115

Fig 6.4: Effect of 1-MCP and storage duration interaction on non-reducing sugars (%)

of peach fruits…………………………………………………………115

Fig 6.5: Effect of 1-MCP and storage duration Interaction on weight loss (%) of peach

fruits ........................................................................................................... 116

Fig 6.6: Effect of 1-MCP and storage duration interaction on fruit decay (%) incidence

of peach fruits ............................................................................................ 116

Fig 6.7: Interactive effect of 1-MCP and storage duration on free radical scavenging

assay (%) of peach……………………………………………………120

Fig 6.8: Interactive effect of 1-MCP and storage duration on catalase activity (U g-1

protein) of peach ........................................................................................ 120

iii

Fig 6. 9: Interactive effect of 1-MCP and storage duration on total phenols (mg GAE

100g-1

) of peach ......................................................................................... 121

Fig 6.10: Interactive effect of 1-MCP and storage duration on antioxidant activity (mg

kg-1

) of peach ............................................................................................. 121

iv

LIST OF APPENDICES

Figure No. Title Page No.

3.1a Analysis of variance for fruit weight (g) of peach fruits as affected by

thinning intensity and time……………….…..……………………………..

179

3.2a Analysis of variance for fruit volume (cm3) of peach fruits as affected by

thinning intensity and time……………………….…………………………

179

3.3a Analysis of variance for number of fruits kg-1

of peach fruits as affected by

thinning intensity and time………………..……………...…………………

179

3.4a Analysis of variance for fruits yield tree-1

(kg) of peach fruits as affected

by thinning intensity and time………………..……………………….……

180

3.5a Analysis of variance for fruit firmness (kg cm-2

) of peach as affected by

thinning intensity and time………………..…………………………….…..

180

3.6a Analysis of variance for total soluble solids (°brix) of peach as affected by

thinning intensity and time………………..………………………………..

180

3.7a Analysis of variance for percent acidity (%) of peach as affected by

thinning intensity and time………………..………………………………..

181

3.8a Analysis of variance for TSS-Acid ratio of peach as affected by thinning

intensity and time………………..…………………………………………..

181

3.9a Analysis of variance for ascorbic acid (mg 100g-1


thinning intensity and time………………..………………………………

181

3.10a Analysis of variance for split pits incidence (%) of peach as affected by

thinning intensity and time………………..………………………………...

182

4.1a Analysis of variance for leaf area (cm2) of peach as affected by irrigation

intervals and gibbrellic acid concentrations…………………..……………..

183

4.2a Analysis of variance for fruit weight (g) of peach as affected by irrigation

intervals and gibbrellic acid concentrations………………..………………..

183

4.3a Analysis of variance for fruit volume (cm3) of peach as affected by

irrigation intervals and gibbrellic acid concentrations………………..……..

183

4.4a Analysis of variance for number of fruits kg-1

of peach as affected by

irrigation intervals and gibbrellic acid concentrations………………..…….

184

4.5a Analysis of variance for fruit yield (kg) of peach as affected by irrigation

intervals and gibbrellic acid concentrations………………..……………….

184

4.6a Analysis of variance for split pit incidence (%) of peach as affected by


184

4.7a Analysis of variance for total soluble solids (0Brix) of peach as affected by

irrigation intervals and gibbrellic acid concentrations………………………

185

4.8a Analysis of variance for fruit firmness (kg cm-2



185

5.1a Analysis of variance for fruit firmness (kg cm2) of peach as affected by

calcium sources, concentration during storage………………..…………….

186

5.2a Analysis of variance for total soluble solids (°Brix) of peach as affected by

calcium sources and concentration during storage………………..………...

186

v

5.3a Analysis of variance for percent acidity (%) of peach as affected by


187

5.4a Analysis of variance for TSS-acid ratio for peach as affected by calcium

sources and concentration during storage………………….…………..……

187

5.5a Analysis of variance for ascorbic acid (mg 100g-1


calcium sources and concentration during storage………………...……..…

188

5.6a Analysis of variance for reducing sugars (%) of peach as affected by

calcium sources and concentration during storage…………………….……

188

5.7a Analysis of variance for non reducing sugars (%) of peach as affected by

calcium sources and concentration during storage………………..………..

189

5.8a Analysis of variance for brown rot incidence (%) of peach as affected by


189

5.9a Analysis of variance for weight loss (%) of peach as affected by calcium

sources and concentration during storage………………..………………….

190

5.10a Analysis of variance for fruit calcium content (%) of peach as affected by


190

5.11a Analysis of variance for ion leakage from cell membrane (%) of peach as

affected by calcium sources and concentration during storage……………..

191

5.12a Analysis of variance for ion leakage from cell wall (%) of peach as

affected by calcium sources and concentration during storage………..……

191

6.1a Analysis of variance for weight loss (%) of peach as affected by 1MCP

concentrations and storage durations………………..……………………....

192

6.2a Analysis of variance of fruit firmness (kg cm-2

) of peach fruits as affected

with 1MCP and storage durations………………..………………………….

192

6.3a Analysis of variance of total soluble solids (0brix) of peach as affected by

1MCP levels and storage durations………………..………………………...

192

6.4a Analysis of variance for percent acidity (%) of peach fruits as affected by

1MCP and storage durations………………..……………………………….

193

6.5a Analysis of variance for TSS-Acid ratio of peach as affected by 1MCP

levels and storage durations………………..………………………………..

193

6.6a Analysis of variance of ascorbic acid content (mg/100 g) of peach as

affected by 1MCP levels and storage durations………………..……………

193

6.7a Analysis of variance for reducing sugars (%) of peach as affected by 1MCP

levels and storage durations………………..……………………………….

194

6.8a Analysis of variance for non reducing sugars (%) of peach as affected by

1MCP levels and storage durations………………..………………………...

194

6.9a Analysis of variance for fruit decay (%) of peach as affected by 1MCP

levels and storage durations………………..……………………………….

194

6.10a Analysis of variance for free radical scavenging activity (%) of peach as

affected by 1MCP levels and storage durations………………..……………

195

6.11a Analysis of variance for catalase activity (U g-1

FW) of peach as affected

by 1MCP levels and storage durations………………..…………………….

195

vi

6.12a Analysis of variance for total phenolic content (mg GAE 100 g-1

) of peach

as affected by 1MCP levels and storage durations………………………….

195

6.13a Analysis of variance for antioxidant activity (mg kg-1

) of peach as affected

by 1MCP levels and storage durations………………..…………………….

196

vii

LIST OF ABBREVIATIONS 1-MCP 1-Methylcyclopropene

Ca Calcium

CaC Calcium concentration

CaS Calcium sources

CRD Completely Randomized Design

DPPH 2, 2-diphenyl-1-picrylhyrazl

DRSA DPPH-radical scavenging assay

DW Dry weight

FW Fresh weight

GA3 Gibrellic acid

GAE Gallic acid equivalents

Non Sig. Non significant

RCBD Randomized Complete Block Design

RDI Regulated deficit irrigation

RH Relative humidity

ROS Reactive oxidative specie

SD Storage duration

TA Percent acidity

TI Thinning intensity

TSS Total soluble solids

Tt Thinning time

UAP The University of Agriculture Peshawar

viii

ACKNOWLEDGEMENT

I am very thankful to ALMIGHTY ALLAH alone the compassionate, Beneficent, Omnipotent, who

gave me the right direction to take right step in the right direction and make me able to complete this

difficult task. Cordial gratitude to the Prophet Muhammad (P.B.U.H), who is forever a torch of

guidance and Knowledge for humanity.

I am very thankful from the core of my heart to the honorable and humble person and affectionate and

devoted Chairman Department of Horticulture, Prof. DR. Noor ul Amin, who always provided me

help and guidance, and always cooperate with me and give me encouragement without any hesitation.

His punctual personality is like an umbrella of discipline over the head of the students. Being the head

of the Department he always encourages and motivates us at every step when we needed during the

study tenure at the department.

The real credit of my Research work goes to my advisor, a very respectable and supported teacher Dr.

Muhammad Sajid, Associate Professor, Department of Horticulture, who provided me his guidance

and support. He is not only a soft spoken and knowledgeable teacher of the department but also a very

cool minded and kindhearted personality as well. When ever, I face any difficulty he is the person with

whom I share it and he tries his best to give me the right direction. I never forget his cooperation,

guidance and encouragement, which he gave me in spite of his professional engagements. He point out

my mistakes and assist me step by step. He left no stone unturned in helping me in the completion of

my research task. I am really very thankful to him for his cooperation and encouragement, which he

gave me without hesitation during my stay at the Department of Horticulture.

I wish to express special thanks to my sincere and honorable teachers Prof. Dr. Abdur Rab, Prof. Dr.

Abdul Mateen Khattak, Dr. Abrar Hussain Shah, Dr. Gohar Ayub khan, Mr. Fazl-i-Whahid, Dr.

Naveed Ahmad, Dr. Imran Ahmad, Dr. Mehboob Alam, Mr. Masood Ahmad, Dr. Nelaam Ara, Dr.

Farzana Bibi and Mr. Saeed ul Haq and, Department of Horticulture, Prof. Dr. Muhammad Jamal

Khan (Chairman, SES), Prof. Dr. Muhammad Arif (Agronomy) and Dr. Mudasir Iqbal (Agri.

Chemistry). They always helped me whenever I needed during my course work as well as my research.

I would also like to place my thanks on record all the support staff members, Department of

Horticulture especially Mr.Imran ullah (Office Assistant) and Mr. Arshad Pervaiz (Superintendent,

Hort.Deptt) who always gave me helping hands whenever I needed the most and who’s informative

advises make my work very easy. I would also like to give special thanks Miss Haleema Bibi (SRO,

ARI, Tarnab), Miss Ghazal Miraj (SRO, ARI, Tarnab) and Mr. Riaz Alam (Assistant Director,

PARC) without them my research may not become possible.

I wish to express the contribution of my seniors, friends and class fellows from whom my dearest and

devoted friends especially Mr. Kamran Azeem (Agronomy), worth mentioning, whose contribution and

sympathetic help make my work easy.

At last but not the least I would like to thank all family members. It would be a blunder on my part to

not mention MY PARENTS who deserve special regards for their financial and moral support

throughout my career and without whose help I might not have been able to achieve. They are like a

cool shadow in the sun for me. May God bless them and may give me chance to serve them better and

make me able to fulfill their expectations.

Syed Tanveer Shah

1


GIBBRELLIC ACID APPLICATION ON FRUIT YIELD AND QUALITY OF

PEACH

Syed Tanveer Shah and Muhammad Sajid

Department of Horticulture, Faculty of Crop Production Sciences,

The University of Agriculture Peshawar

January, 2017

THESIS ABSTRACT

A research study entitled “Influence of thinning intensity, calcium and gibbrellic acid

application on fruit yield and quality of peach” was conducted at Horticulture

Research Farm and Post harvest Laboratory, The University of Agriculture Peshawar

(UAP) in the year 2014-15. The present research project consists of four interlinked

experiments. The 1st experiment entitled “Effect of thinning intensity and time on

quality fruit yield of peach”. Various thinning intensity i.e. 0, 20, 40 and 60% and

thinning time i.e. 7, 14 and 21 days after fruit set) were carried out in peach fruit trees.

The experimental results showed that peach fruits trees thinned 60% after 7 days of

fruit set significantly improved all the studied attributes but showed more split pits

incidence and inferior quality yield of peach. However, the results of 60% fruit

thinning were statistically at par with peach fruits thinned 40% after 14 days of fruit

set with less split pits incidence and good quality fruits, hence recommended for

better quality fruit production of peach. In order to overcome the problem of split pits,

another field experiment entitled “influence of irrigation intervals and gibbrellic acid

concentrations (GA3) on the split pit incidence and fruit quality of peach” was

conducted during the year 2015. Keeping irrigation intervals in main plots and various

concentrations of GA3 in subplots, peach trees were irrigated with different intervals

(5, 10 and 15 days), sprayed with gibbrellic acid (GA3) concentrations (0, 50, 100 and

150 ppm) in already thinned plant (40% fruit thinning after 14 days of fruit set)

optimized from the previous year experiments. The experimental results showed that

peach fruit trees irrigated after every 10 days significantly increased the leaf area and

other fruit and quality related attributes but most importantly reduced the incidence of

split pits. Moreover, application of 100 GA3 concentration proved to be the best in

controlling split pit incidence of peach with improving the yield and quality related

attributes of peach. Hence, peach fruit trees could be irrigated after every 10 days

along with 100 ppm GA3 concentration for better quality fruit production of peach

with minimum incidence of split pits. As peach is a highly perishable commodity with

short post harvest life. Hence, the third pre and post harvest experiment was

conducted to retain the quality attributes of peach with longer shelf life. Various

calcium sources (Calcium chloride, calcium nitrate and calcium sulphate) were

sprayed at different concentration (0, 0.50, 0.75 and 1.0%) on peach fruit trees and the

2

harvested fruits were kept in storage for 30 days with 10 days interval having storage

temperature of 8±2 0C at 50% Relative Humidity. The experimental results showed

that some of the quality attributes like fruit firmness, fruit calcium content, TSS,

TSS-acid ratio of peach fruits were better retained for 30 days by the pre harvest foliar

application of 1.0% CaCl2 with minimum percent brown rot incidence, weight loss,

ion leakage from cell membrane and cell wall. However, the effect of calcium sources

and concentration on other quality attributes such as ascorbic acid content, percent

acidity, reducing sugars and non reducing sugars of peach fruits were found

non-significant. Pre harvest application of calcium chloride at 1% significantly

retained the pre harvest and some of the post harvest attributes but could not retained

the other studied quality attributes of peach, so to further enhance the quality of peach

fruits, another post harvest experiment entitled “effect of 1-Methylcyclopropene

(1-MCP) concentrations on storability of Peach fruit cv. Early Grand” was conducted

during year 2015. Optimum source and dose of calcium (optimized from the previous

experiment i.e. calcium chloride at 1%) was applied pre harvest to peach fruit trees.

The treated fruits were then dipped in different levels of 1-MCP (0, 0.3, 0.6 and 0.9

µg L-1

), stored for 40 days at temperature of 8±2 0C with 50% RH. The experimental

results showed that 1-MCP at 0.9 µg L-1

reduced weight loss, fruit decay, total soluble

content, TSS-acid ratio while retained fruit firmness, acidity, ascorbic acid, reducing

sugars, free radical scavenging assay, catalase activity, total phenols and antioxidant

activity of peach fruits. Peach fruits stored for 40 days showed better performance for

most of the quality attribute up to consumer preferences. However, free radical

scavenging assay, catalase activity, total phenols and antioxidant activity increased up

to 30 days but declined up to 40 days of storage. Therefore, an integrated management

of peach fruits with 40% thinning after 14 days of fruit set, irrigated after 10 days,

sprayed with 100 ppm GA3 concentration enhanced the fruit size, weight, yield and

quality of peach fruits with lower split pit incidence. Moreover, peach fruits trees

could be sprayed with CaCl2 at 1.0% and later on treated with 0.9 µg L-1

1-MCP

solution for retaining the quality attributes of peach fruit up to 40 days of storage

(Temperature = 8±2 0C and 50% RH).

3

CHAPTER I

GENERAL INTRODUCTION

PEACH

Among the stone fruits peach (Prunus Persica L.) is one of the major fruit crop of

Pakistan, belongs to family Rosaseae (Chaudhary, 1994). Peach is native to south

china and was first domesticated in China around 4000 BC. Then it moved to Persia

where it got its name (Bassi and Monet, 2008). History shows that peach was

domesticated in Far East geographical origin, in way back from 3000 B.C (Li, 1984),

acknowledged in the 19th

century (De-Candolle, 1883; Hedrick, 1917; Vavilov, 1951).

Peach fruit having high nutritive value containing 165 KJ (39 kcal) of energy, which

includes carbohydrates (9.5 g, of which sugars are 8.4 g and dietary fiber is 1.5 g),

fats (0.3 g), proteins (0.9g), vitamin C (6.6 mg i-e 8%), Iron (0.25 mg i-e 2%) and

Pottasiun (190 mg i-e 4%) as per 100g (USDA Nutrient Database, 2011).

Status of Peach in Pakistan

Among the stone fruits in Pakistan, peach is the second most important fruit after

plum. In the Northern areas of Pakistan, peach is one of the traditional crops of the

locality. The main growing areas of peach in Pakistan include Quetta, Kallat,

Peshawar, Swat, Kohistan and some areas of Punjab which includes Pothwar, etc. In

Pakistan, total area under peach production is 15.2 thousand hactares with the total

production of 5.2 thousand tonnes. As concerned Khyber PukhtunKhawa province,

peach is grown on an area of 5.6 thousand hactares with an annual total production of

30.8 thousand tonnes. Baluchistan province shares annual total production of 21.4

thousand tones grown on an area of 9.5 thousand hactares, while in Punjab province

the total area under peach cultivation is 0.1 thousand hactares with a total average

production of 0.4 thousand tones. Sindh province contributes the least suitable place

where peaches are not being cultivated (MINFA, 2013-14).

Climatic Requirements

Continental, dry and temperate climate is required for peach production, though it

4

requires chilling hours which can be satisfied under tropical and sub tropical areas

except at higher altitudes. Most of the peach cultivars requires chilling hours in

between 600 and 1000 hrs and temperature around 0-10 0C (32-52

0F). On the

fulfillment of the chilling period, the plant enter into quiescence period, another type

of dormancy, in which buds break occurs and they grow when there is adequate

favorable warm weather for the accumulation of growth (Szalay et al., 2000).

The peach trees can tolerate temperature around 26-30 0C, although following the

season, flowering buds are killed at these temperatures. Usually, the death of

flowering bud began in a temperature between 15-25 0C depending upon the cultivars

and cold timings, where buds become less tolerant to cold in late winter. Spring frost

is another climatic constraint, where the tree flowers early and blossom is killed or

damaged, if the temperature drops below -4 0C. Sometimes they can tolerate a few

degree cold, in a situation where the flowers are not fully opened. Similarly, the

climate with winter rainfall at temperature below 16 0C significantly damages the

peach cultivation as it encourages peach leaf curl, a threatening fungal disease of

peach. Summer heat is required for maturation of peach fruit with the mean

temperature between 20 and 30 0C (Szalay et al., 2000)

Soil Requirement

Peach fruits are usually susceptible to water-logged soils, so for a long survival of tree

good to excellent internal soil drainage is very essential. The ideal soil for peach

cultivation is sandy loam top soil, which is at least 18 to 24 inches deep underlain,

with a red color, well drained clay sub soil. A sub soil usually has poor drainage

characteristics as it is dull colored blue, gray or mottled and thus not satisfactory for

peach. The sub soil and the top soil must be fertile having satisfactory nutrients with

good water holding capacity and it must be permeable for the movement of water, air

and roots (Szalay et al., 2000).

Common Peach cultivars

Peach having two common types of varieties or cultivars, grown world wide are cling

5

and free stone. In Pakistan, the most used peach cultivars are Florida King, Early

Grand, 6th

A and 8th

A, Shireen, Shah Pasand, and Golden Early. In Swat and

Peshawar region Early Grand, Florida King, Spring Crest, NJC-84, 6th

A, Maria

Delizia and Indian Blood are mostly grown cultivars, while in Baluchistan, Shah

Passand, Golden Early and Shireen are grown (Chaudhary, 1994).

Problems in Peach

Peach fruit faces many problems which includes quality, yield, invasions and pests etc.

It is attacked by so many diseases which includes peach scab, brown rot, anthraxnose,

bacterial spot etc (Hartman, 2007). Peach may receives many extensive losses, if there

are favorable conditions for pest and diseases during different growth stages (Robson

et al., 1989). Peach fruit is also subjected to pre harvest contamination and physical

damage due to which problems like surface disscolortion etc may occur (Crisosto et

al., 2000). Growth conditions, harvesting stages and post harvest factors like chilling

temperature susceptibility affects the quality of peach fruit (Serrano et al., 1996).

Peach fruits, being climacteric in nature, is highly perishable with short postharvest

life (Lill et al., 1989).

Peach fruit trees that produce abundance of flowers annually and sets surplus of

fruitlets, which is unable for the tree to support and achieve adequate fruit size for

commercial purpose. For maintaining an adequate number and size for commercial

purposes, thinning is necessary (Reighard et al., 2006).

Peach also faces flower and fruit drop which might be due to missing of sex organs,

non functional flowers and failing of pollen germination. Flower abscission hinders

pollination and fertilization process (Yoshida et al., 2000).

In order to increase fruit size and improve fruit quality and color, common techniques

like thinning of flowers and fruits are very effective (Costa and Vizzotto, 2000).

Thining intensity increases the usefullness of thinning, though it is cultivar dependent.

Early ripening cultivars are more susceptible than late maturing one which requires

severe thinning (Costa and Vizzotto, 2000; Pavel and De-Jong, 1993).

6

Most of the peach trees in the favorable conditions produce thousand of flowers and

they set several thousands of fruits tree-1

. If all the fruits are allowed to develop, the

fruit weight breaks the branch and thus having low concentration of sugars, which

resulted in reducing market value of the fruits. In order to control the reduction in the

market value, the fruits number tree-1

should be regulated. The stranded commercial

techniques like fruit thinning in the peach orchard could be practiced to obtain the

quality fruit production (Layne and Bassi, 2008).

Crop Load Management

Crop load is defined as the measure of fruiting density typically expressed as number

of fruits per trunk or branch cross section area, or per tree canopy volume (Stover et

al., 2004). In order to reduce crop load before or during the bloom and maximizes

fruit size, hand thinning becomes less effective for each day when there is a delay in

bloom thinning (Byers et al., 2003). It is usually noticed that the unwanted fruits

remain on the tree for longer time, may have a negative effect on the fruit size, tree

growth, flower bud differentiation, flower bud hardiness, the next season crop

potential and tree survival (Byer et al., 2003; Myers et al., 1996)

The high density fruit production system relies upon intensive crop load management

strategies (Whiting et al., 2006). In many stone fruits, crop load management is

primarily done through chemicals, mechanical means and by hand thinning, though

the hand thinning has potential for peaches as shown by many of the researchers

(Byers and Lyons, 1985; Southwick et al., 1996).

Fruit Thinning

Improvement of fruit color, size, edible quality market value and ensuring the healthy

plants is usually termed as fruit thinning (Peter and Abraham, 2007; Carlos et al.,

2006), which maintains optimal fruit to leaf ratio (Meland, 2009). This ensures the

reduction of limb breakage (Peter et al., 2011) and better growth of fruits (Meland,

2009).

Fruit thinning is now one of the commercial practices for the removal of fruits, though

7

hand removal of excess fruits is a laborious pre-harvest activity in the production of

peaches, but on the other hand it is absolutely necessary to produce salable crops. For

the last half century peach industry is in search of less expansive ways to remove

unwanted fruits (Layne and Bassi, 2008). Heavy manual thinning in peaches is done

for proper development of size, thus leaving 1 fruit after every six inch of branch

length and makes it a costly method. Furthermore, chemical are also used for flower

thinning but in case of peach, no chemical thinning is practiced (Corelli and Coston,

1991).

For many years, hand thinning is one of the most commonly used method for

reducing the crop load on peach trees. The general thumb rule is being followed to

space fruits about 12, 15 and 20 cm apart for large, medium and small fruit cultivars,

respectively. In some regions distance between fruits is not considered rather fruit

number per shoot is varied depending on shoot location in the canopy or season of

harvest. In the bottom 2 or 3 fruits shoot-1

is retained while 3 or 4 in the middle of the

tree and 5 fruits in the top of the tree are retained. Retaining of fruits shoot-1

may also

vary from 3 for early season cultivars and 4 to 6 for late season cultivars (Clanet et al.,

1983 and Southwick et al., 1996).

Split pits of Peach

Split pits are splits or opening pits of the fruit at the bottom end of the fruit thus these

splits become evident during the final swell which is the third stage of the fruit growth.

The weakening of pits occurs usually in the later stage of pit hardening which leads to

the opening at the stem end. The immature fruits having abnormal sutures shape often

manifests split pits symptoms during final swell. In peach production usually split pits

are long recognized problem. Splitting in peach shows as split fruits and as split pits

with the pit still intact (Byrne et al. 1991).

Split pits usually occur 20 days after bloom or during the stage of pit hardening. Early

peach varieties are often noticed with this problem but in some cases the late varieties

also show this problem. Certain environmental factors like rainfall are not responsible

8

for split pits but they may aggravate this problem. There is also no consistent

association between micro nutrient access or deficiency in split pits and trees (Patten

et al., 1989).

It has been known that shattered and split pits severely occurs in early ripening peach

cultivars in which hardening of pits and the final stages of fruit growth occur

somewhat closed together (Byrne et al. 1991). For cultivars that ripen early, final

stage of growth occurs prior to the adherence of pit and flesh creates pulling of pits

due ot the expansion of flesh of the fruit. The weakest sites of the pits weakens and

finally breaks, if these forces are greater enough (Barcelon et al. 1999).

Generally the cultural practices like thinning, good nutritional program and irrigation

normally enhances the fruit sizes but may also increases the level of shattered pits and

split pits (Beppu and Kataoka, 1999). Recent study showed that girdling is helpful in

enhancing the fruit yield and size without aggravating the well known shattered pits

or split pits problem of certain peach varieties. Studies also indicates that imbalance

of carbohydrates between roots and leaves increases the problem of split pits which

includes girdling, winter injury heavy watering high heat excess vigor or trunk

damage. Soft sutures is another problem in peach regarding splitting, it might be due

to the soil moisture which leads to split pits incidence. Some varieties tend to be more

prone to soft sutures symptoms (Xiahong et al., 1998).

Proper management of irrigation and gibbrellic acid application helps in decreasing

split pits incidences in peach. Fruits with shattered pits or splits and double fruits are

usually unmarketable. Hand thinning helps in removing such types of problem.

(Patten et al. 1989). Some cultivars of peach have 40-70% double or split pits, these

problems increases with the climatic conditions and improper management practice of

irrigation, fertilization and hormonal regulation (Engin et al., 2010). Previous studies

had reported that flower bud initiation is delayed by heavy crop load (Barnard, 1938),

low light intensity and high temperature (Larson et al. 1988; Harai et al. 1961),

drought (Grigonov, 1964; Harai et al. 1961). In previous years investigation on the

9

influence of stress on splitting pits has been studied during the months of summer

(Patten et al. 1989) and reported in increased development of double fruits in the

coming seasons. Fruit quality (increment in TSS and decrease in fruit size) is greatly

affected by giving stress during last phase of fruit growth (Besset et al. 2001; Bussi et

al. 1999; Crisosto et al. 1994; Li et al. 1989).

Imbalance of hormons also results in split pits and formation of double fruits (Patten

et al., 1989). Gibbrellic acid is well known in inhibiting differentiation of flower buds

winter fruits (deciduous in nature). Moreover, the foliar application of gibbrellin

during the period of differentiation of flower delayed the bloom, increase fruit size

and reduces the incidence of split pits and double fruits (Taylor and Taylor, 1998).

Post harvest losses in peach

The maximum life of a fruit is usually 3-5 days provided with normal conditions for

storage. During harvesting and marketing, the major factors behind short post harvest

life of peach is high temperature with low relative humidity (Tonini and Tura, 1998).

Due to less attention, perishability factor and short post harvest life, all horticultural

crops faces 17-40% losses especially peach (Rind, 2003). These losses starts right

from the harvest and thus results in both quality and quantity losses. The main reasons

for these post harvest losses of fruits and vegetable are due to certain cultural

practices during the pre harvest period. It involves selection of non compatible root

stock and scion, lack of improved production practices, management of fertilizers and

improper pest and disease, lacking skills for identifying improper harvesting stage and

post harvest problems which includes improper management of hygene, imbalance of

field heat removal, improper packaging material, poor fruit grading, transport storage

and marketing faciliaties (Kader, 2002).

For getting high yield and good quality fruits, huge efforts are being done but beside

these efforts, there are many other challenges to be faced during post harvest. As

peaches are climacteric in nature, they pass through high rates of biological activities

like respiration and ethylene production which leads the fruits towards ripening and

10

detoriation. In order to overcome these losses due to increased respiration and

ethylene rates, different post harvest techniques are being used which includes

properly sanitized equipment's, appropriate relative humidity, temperature

management and gasses exchange during storage thus enhanced the post harvest life

of fruits (Young, 2002; Schoellhorn et al., 2003; Armitage and Laushman, 2003).

Besides these activities, injuries, abrasion and mechanical wounding also increased

the process of detoriation and reduced the post harvest life of peach fruit (Cappellini

and Ceponis, 1984). Another reason for short post harvest life and quality loss of

peach is also due to the physical damage. The process of oxidation produces free

radical thus resulted in electrolyte leakage and leads to the tissue destruction.

Increased activities of antioxidants results in minimizing the damage caused by free

redicals which results in improvement of shelf life of peach (Abbasi and Kushad,

2006; Abbasi et al., 1998).

Role of calcium and 1 MCP in decreasing the post harvest losses

Calcium, a component of cell wall and plays a vital role in cell wall strengthening by

forming cross bridges and before cell separation; they are regarded as a last barrier

(Fry, 2004). Protection of enzymes that results in the degradation of cell wall and

making it stable is due to the exogenous application of calcium (White and Broadley,

2003). In softening and ripening of fruits, different cell wall degrading enzymes are

involved, includes polyglacturonase and pectin methyl esterase (Hadfield et al., 1998;

Micheli, 2001). Improving fruit characteristics and minimizing fungicides sprays, pre

harvest application of calcium is one of the important practices of new strategies

applied in integrated fruit production systems (Conway et al., 1987). Calcium sources

especially CaCl2 are extensively used for sprays (Lester and Grusak, 2004).

Calcium, a secondary messenger, is a basic component of cell wall structure, that

leads to the growth, development and quality of fruit (Kazuhiro et al., 2004),

minimized fruit senescence (Gerasopoulos and Drogoudi, 2005), increase disease

resistance (Lanaouskas and Kvikliene, 2006; Tobias et al., 1992) and, other stresses

11

(Yuen, 1993). Formulation, time and rate of calcium greatly affect the biochemical

attributes of peach (Elmer et al., 2006; Kazuhiro et al., 2004).

One of the new strategies in integrated fruit production for the improvement of quality

fruit attributes and reducing the effect of fungicide spray at the end of harvest period,

is the pre harvest foliar application of calcium. It also improves the resistance against

diseases as well (Conway et al., 1987). Among the different calcium sources, calcium

chloride based formulations are most widely used (Lester and Grusak, 2004).

The movement of calcium in fruits is conflicting and not distinctly known but

exogenous calcium sprays gives a supplemental calcium that increases the calcium

content of fruits in a variety of fresh fruits especially peach (Serrano et al., 2004;

Raese and Drake, 2000a,b; Crisosto et al., 2000; Tzoutzoukoua and Bouranis, 1997).

Researches have shown that calcium penetration into the fruit is through lenticels,

which are present on fruit surface. Moreover, discontinuities and cracks in fruit

surface are the prominent areas for entering calcium during the final phase of fruit

growth (Glenn et al., 1985).

The application of 1-methylcyclopropene (1-MCP) is one of the new techniques to

improve the shelf life and quality of fruits. The importance of 1-MCP is not only in

commercial agriculture but it is also reported that it provides new approaches to

explain ethylene synthesis and ethylene responses in regulating plant processes

(Blankenship and Dole, 2003). Watkins (2002) reported the influence of 1-MCP on

fruit in relation to ethylene physiology. Electrolytic leakage, decline in membrane

protein, and lipid fluidity due to ethylene is retarded by the application of 1-MCP. It

also enhanced shelf life of flower, fresh weight and total protein content (Serek et al.,

1995). Like other horticultural plants, stone fruit have also been tested with a wide

range of 1-MCP concentration and it was reported that a concentration of 0.05-1 mlL-1

was effective in reducing the synthesis of many cell wall degrading enzymes

(polygalacturonase, galactosidase and endo-glucanase/glucosidase), leading to delay

in fruit softening (Dong et al., 2001b; Manganaris et al., 2007). Modern researches

12

have shown that exposure of fruits to 1-MCP before keeping them in ethylene resulted

in better effect on delay in fruit ripening at the time of harvest but full ripening after a

period of cold storage (Sisler and Serek, 2003; Reid and Celikel, 2008; Apelbaum et

al., 2008; Zhang et al., 2009, 2010).

Keeping in view the importance of peach in our daily life and the problem related to

the decline in fruit quality and yield, the present study was carried out with the

following objectives.

To optimize the fruit thinning intensity and time for quality fruit production of

peach

To minimize the split pit incidence in peach fruit by application of various

concentrations of gibbrellic acid and management of irrigation intervals

To optimize the calcium source and concentration in order to retain the fruit

quality attributes during storage

To standardize the optimum levels of 1-MCP to enhance the storage life of

peach fruit

13

CHAPTER II

REVIEW OF LITERATURE

Different researches and work done by other researchers were searched on “influence

of thinning intensity and foliar application of calcium on the fruit yield and quality of

peach” but very little work on thinning management of fruits especially peach has

been carried out. The following paragraphs show the work done on this particular

topic and other related researches and their summeries are briefly given as under.

Crop load management

Crop load management is a key to success in producing better size and quality of

fruits (Andreea et al., 2013). Limb breakage, less reserves for the fruits, small sized

fruits, inferior fruit quality and reduced cold resistance is closely associated with too

much load on the crop (Andreea et al., 2013). High density fruit production system

relies upon intensive crop load management strategies which results in the production

of superior quality fruit yield (Whiting et al., (2006). Physiological properties of the

fruits retain with removing smaller fruits leaving healthy fruits. Furthermore,

accumulation of substances inhibits the floriferous buds’ differentiation by thinning

the fruit that ensured the increase in vegetative growth with bigger and better quality

fruits (Andreea et al., 2013). Source sink relationship plays a significant role in

assimilate partitioning among plant organs. Source sink relationship directly affects

the photosynthetic performance and development of reproductive organs (Max et al.,

2016). The factors recognized for the deterioration of fruit quality and reduction of

marketable yield (Mutwiwa et al., 2008) is poor fruit set, high number of undersized

fruits (Liebisch et al., 2009; Max and Horst, 2009). Hence, fruit thinning is a simple

and inexpensive method to maneuver the source-sink relationship in peach fruit that

overcome the heavy crop and fruit load on the tree. Assimilate partitioning in the sink

largely depends on the strength of the source, sink and assimilate availability unless

and until light is limiting (Heuvelink, 1995; Ho, 1996). During the reproductive

growth stage, the fruits represent the strongest sinks among the organs (Cockshull and

14

Ho, 1995). The overall sink strength of the gerenative organs and competition

between individual fruits for the photoassimilates are improved by thinning and

pruning. Thus, maintaining a proper fruit to leaf ratio which positively affects in

heavy fruit yield (Samira et al., 2014) and fruit quality as well (Hesami et al., 2012).

An option for optimizing carbohydrates and assimilates partitioning between the fruit

and leaves decrease the undesired fruits and improve the fruit yield by producing

heavy fruits (Max et al., 2016). Several studies showed the importance of crop load

management in many fruit plants. Meitei et al. (2013) used gibbrellic acid and some

other chemicals like ethral and thiourea, as thinning agents. Application of gibbrellic

acid improved fruit yield and quality of peach by reducing fruit drop while the others

had a negative effect on the yield and quality attributes of peach. Drogoudi et al.

(2009) evaluated the effect of light, moderate, or heavy thinning on the occurrence of

split pits, fruit yield, fruit quality characteristics and leaf mineral contents of canning

peach (Prunus persica L. Batsch.) cv. ‘Andross’ over two growing seasons. Heavily

thinned trees showed more incidence of split pits as compared to moderately or lightly

thinned trees. Drogoudi et al. (2009) reported an increased fruit fresh weight (FW) in

moderately and heavily thinned trees compared with lightly thinned trees which

showed antioxidant capacities and phenolic contents, but yields were similar among

the different crop load treatments. Earlier thining results in improvement in all the

attributes of peach. Gordon and Dejong (2007) evaluated that, crop loading and

epicormic sprout removal on current and subsequent-year distribution of vegetative

growth among epicormic, long and short shoots in Prunus persica. Gordon and

Dejong (2007) reported an increase in long-shoot dry weight and node number by

decreasing crop load and observed epicormic sprouting problem. Epicormic sprouting

was significantly reduced with thinning treatment which increased the fruit size as

well. Another study showed that fruit and shoot number management play a vital

importance in improving fruit quality in peaches (Prunus persica L. Batsch). An

inverse relation was observed between fruit weight and total soluble solids of peach,

15

which clearly indicated utilizartion of the available photosynthates. In the same study

low and high pruning levels were applied each year for the same fruit load. The results

of the study showed that with high pruning (60 shoots/tree in 2002), fruit weight and

diameter was increased and as a result yield was also increased (Siham et al., 2005).

Myers et al. (2002) used partial flower thinning as a crop load management strategy

and reported that partial thinning after 42 days after full bloom (DAFB) increased the

percentage of fruits with larger diameter (≥62.0 mm), development of flower buds

shoot-1

and node-1

. Barbosa et al. (1991) concluded that hand thinning after 30 days of

anthesis by keeping 60 fruits tree-1

significanlty enhanced the fruit weight and yield of

Aurora-1 peaches as compared to Tropical cultivar of peach. Crop load management

is not only confined to peaches but it is also important in many other fruits plants like

citrus (Ouma, 2012), apricot (Rab et al., 2012), guava (Khan et al., 2013). In a study

on citrus, Ouma (2012) applied flowers or clustered of flower removel or single

fruitlets after fruit set through thinning. All the treatments improve the yield and

flowers of citrus in next year. Rab et al. (2012) used manual thinning in apricot trees

and reported that 40% thinning although reduced the fruit drop and yield but

increased the fruit weight of apricot. Furthermore, 40% thinning also improved the

biochemical attributes as well like ascorbic acid content, TSS, reducing and

non-reducing sugars but decreased the fruit pulp acidity resulting a decrease in pH.

Khan et al. (2013) recorded increase in fruit size, retaining reducing sugars, total

soluble solids and better scores of organolaptic attributes of guava trees when

subjected to 50% deblossming in summer as well as in the winter. He also observed a

non significant response of defoliation and deblossoming to the physical fruit quality

characteristics of guava. Several studies have also revealed the importance of crop

load management in vegetables as well. In a study on tomato, shoot pruning (single

branch pruning, double branch pruning, pyramidal pruning and control) and flower

thinning (Cluster with 4 and 5 remained flowers and control) significantly increased

the leaf area and plants yield were higher in both the thinning (cluster thinning with 5

16

remaining flowers) and pruning (pyramidal pruning) treatments as compared to

control (Hesami et al., 2012).

Split pits Management of peach through irrigation and growth hormones

Split pit incidence is more common in stone fruits especially peach (Barcelon et al.

1999). The importance of split pits and double fruits are well documented by Engin et

al. (2010). He reported that peach faces certain physiological disorders which can be

minimized by the management of nutrients (nitrogen at 300 mg L-1

), hormones (GA3

at 150 mg L-1

) and irrigation (100% and 20% water stress). Peach physiological

disorders (split pits and double fruits) were significantly reduced by all the three

factors. Water stress significantly increased the incidence of double fruits which was

decreased by the application of GA3 and nitrogen application. Excess irrigation water

increased the occurance of split or shattered pits, which inturn was reduced by

managing the irriagation intervals and the use of GA3. Sotiropoulos et al. (2010)

induced water stress by regulated deficit irrigation (RDI) during different fruit growth

stages of peach. Regulated deficient irriagation at II stage of growth to the peach tree

did not influence fresh and dry mass with lower productivity but pre harvest drop of

fruit was greatly minimized. Increment in TSS and TSS-acid ratio was also observed

with no effect on fruit firmness and acidity. Furthermore, regulated deficient

irriagation at growth stage II alone as well as at pit hardening phase showed increased

‘double’ fruits and fruits with open cavity (split/shattered pits) in comparison to the

control. Berman and Dejong (1997) reported that, water stress reduced the fruit fresh

weight of peach at all crop loads; however, fruit dry weight of peach was not affected

by water stress in trees having light to moderate crop loads, indicating that the degree

of water stress imposed did not affect the dry weight sink strength of fruit. Water

stressed trees with heavy crop loads had showed increased incidence of split pits and

double fruits of peach, which were likely due to carbohydrate source limitations

resulting from large crop carbon demands and water stress limitations. Johnson et al.

(1994) exposed plum fruits to postharvest water stress (Control, 50% and cycles of on

17

and off irrigation). Results showed that irrigation stress of 50% and cycles of

irrigation did not affect the yield attributes of plum. Die back disorder was drastically

reduced by water stress. Irrigation management also reduced the occurrence of split

pits of plum. In another study by Johnson et al. (1992) early maturing peach trees

(Prunus persica L. cv. Regina) were subjected to to three levels of postharvest

irrigation (10 to 15 cm of water at 2- 3 weeks interval) over 4 years. Flower and fruit

number were greater in the dry treatment than the control. Number of double fruit and

split pits incidence of peach was greatly increased with irrigation treatment. They

further elaborated that under normal commercial hand thinning, yields and fruit size

of peach were not different among the three treatments over all 4 years. In the study,

they also found that either too much or less irrigation stress significantly increase the

incidence of double fruits and split pits respectively. Larson et al. (1988) stressed

peach tree under full, medium and no irrigation. A significant variation was recorded

on the seasonal stomatal conductance pattern. Dry or no irrigation reduced the tree

trunk upto 33%. Fruit set in dry treatment was more as compared to medium and full

irrigation treatments. Wang and Gartung (2010) reported that infrared temperature

sensors are used to assess plant water status for field and row crops but not for fruit

trees such as peaches. Four irrigation treatments (furrow, subsurface, drip irrigation

and no water stress) were given to peach orchad where 12 infrared temperature

sensors were installed. A close relation was observed between canopy-air temperature

and stem water potential which shows that irrigation event could be triggered with

canopy temperature.

Calcium and Post Harvest Management of Peach

Due to less attention, perishability and short post harvest life, all horticultural crops

faces 17-40% losses especially peach (Rind, 2003). Calcium, a divalent cation is an

important plant nutrient. It plays a key role in maintaining the integrity of cell wall

and cell membrane. It also acts as an intracellular messenger in the cytosol

(Marschner, 1995). Calcareous soils are dificent in calcium that badly affect the plant

18

growth. Calcium is mostly taken up by the plants through roots from the soil solution

and also supplied though shoot as a foliar spray which is taken up the shoot xylem

(White, 2001). Calcium application to plants increases the resistance to abiotic

stresses (White and Broadly, 2003) and many other physiological stresses (Bangerth,

1979). It also helps to reduce the rate of respiration and ethylene production in many

fruits crops including peach (Garcia et al., 1995). The main reasons for these post

harvest losses of fruits and vegetables are due to certain cultural practices during the

pre harvest period which involves selection of improper root stock and scion, poor

production practices, use of fertilizers, skills require at proper stages of harvesting and

storage techniques (Kader, 2002). Biggs et al. (1997) reported that fungal PG activity

in peach was reduced by all the application of calcium sources but the response to

dibasic calcium phosphate and calcium tartrate was found non significant. Monilinia

fructicola growth was significantly reduced by all the salts namely calcium formate,

calcium pantothenate, and dibasic calcium phosphate. Calcium propionate showed

nimimum growth Calcium hydroxide, calcium oxide, calcium silicate, and calcium

pyrophosphate reduced growth by approximately 65% compared with the control. In

another study on peach, Gupta et al. (2011) reported that CaCl2 (6%) treated peach

fruits cv. ‘Early Grand’ showed a significant reducation in physiological weight loss

and fruit spoilage. Furthermore, the same concentration also retained all the quality

attributes of peach stored at room temperature and cold storage. Val et al. (2010)

sprayed calcium as foliar on peach fruits and observed that fruit calcium content were

significantly affected by foliar application of calcium at 1% but with decreased

firmness and increased fruit drop as well. In other studies on peach (Manganaris et al.,

2005) and apricot (Tzoutzoukoua and Bouranis, 1997), pre harvest calcium foliar

srpay was used to study the post harvest quality attributes of the fruits. Results of their

study showed that peel and flesh calcium content of peach (Manganaris et al., 2005)

and apricot (Tzoutzoukoua and Bouranis, 1997) was significantly increased by foliar

application of calcium with no effect on ethylene production of peach fruits

19

(Manganaris et al., 2005) but foliar application significantly decreased the ethylene

production of apricot (Tzoutzoukoua and Bouranis, 1997). Both the fruits showed

delayed respiration rate, uronic acid content and activity of pectin-modifying enzymes.

Brown rot incidence of peach also decreased by the application of calcium. The effect

of pre harvest calcium nitrate and boric acid on date palm fruits was studied by

Sarrwy et al. (2012) and concluded that fruit set, yield and quality was increased by

the foliar application of calcium at 2% and boron at 500 ppm. Akram et al. (2013)

studied different levels of calcium on the post harvest life of mango. Results showed

that vegetative attributes related to leaf, photosynthesis and fruit related attrtibutes

were improved by foliar application of calcium. Irfan et al. (2013) reported an

increase in ascorbic acid and color with reduction in yeast and mould incidence of fig

fruit by the application of calcium. Hence it was concluded that calcium not only

prolonged the shelf life but also cause slow ripening of fruits.

Role of 1-MCP in Post harvest management of Peach

Liu et al. (2005) studied that, effect of 1-methylcyclopropene (1-MCP) on the

ripening and disease resistance of peach fruit (Prunus persica L. cv. Jiubao). Peach

fruits treated with 1-MCP effectively improved fruit firmness, slow down fruit

softening. Post harvest decay was significantly inhibited by repeated treatment of

peach with 1-MCP. Ozkaya et al. (2016) studied the effect of modified atmosphere

packaging (MAP), with 1-methylcyclopropene (1-MCP: 0.5 or 1 L/L for 24 h at 0 ◦C)

on the post harvest quality of nectarines cv. ‘Maria Aurelia’. Both 1-MCP doses and

MAP maintained firmness. Reduction in chilling injury, pectin methyl esterase

(PEM), polyphenol oxidase (PPO) and polygalacturonase (PG) fruits was found in

fruits kept in MAP treated with 1-MCP. Both the methods should be used in

maintaining the post harvest quality of nectarine fruit. Ullah et al. (2016) exogenously

applied 1-MCP and ethylene for extending the post harvest life of ‘Arctic Pride’

nectarine. They found that fruit softening of nectarine was significantly reduced the

activities of softening enzymes (pectin esterase (PE), endo-1, 4-β-glucanase (EGase),

20

endo-polygalacturonase (endo-PG), exo-polygalacturonase (exo-PG)) by lowering

ethylene production in fruits treated with 1-MCP, hence delayed the ripening process

in nectarine. Tavallali and Moghadam (2015) used various bio regulators (AVG at 0,

255 and 310 mg L-1

and 1-MCP 0 and 1 μL L-1

) for maintaining fruit quality and

increasing the shelf life of ‘Kinnow’ (Citrus reticulate Blanco). Results showed that

AVG at 255 mg L-1

with 1-MCP (1 mg L-1

) resulted in reduced occurance of chilling

injury, weight loss and decay with a marked improvement in firmness of fruit, total

soluble solid contents, percent acidity, vitamin C content and TAA.

Moreno-Hernandez et al. (2014) used various treatment (1-methylcyclopropene

(1-MCP) and wax emulsions, alone or combined) for enhancing the post harvest life

of soursop. Fruits treated with 1-MCP combined with flava emulsion maintained a

greater extent of vitamin C content, dietary fiber, total phenolics content, and

antioxidant activity were greatly retained by the application of 1-MCP along with

flava emulsion. Lee et al. (2011) concluded that, decrease in ethylene production and

respiration rate were observed in fruits treated with 1-MCP at all the three stages, that

were drastically enhanced in all stages of control fruit until 11 days after harvest,

which were afterwards decreased till the end of the experiment. Fruit firmness, TA,

and enthanol concentration were significantly delayed in 1-MCP-treated fruit in all

stages. A non-significant response was observed for total phenolic contents,

antioxidant capacity and total flavonoid contents of plums. Cantin et al. (2011)

investigated the effect of 1-methylcyclopropene (0.0, 0.5, 1.0 μl L-1

) in the softening

of ‘Hayward’ kiwifruit under different cold storage conditions. 1-methylcyclopropene

(1-MCP) delayed the fruit softening of kiwifruit during cold storage. Highest

concentration of 1-MCP improved the fruit firmness. Jiang et al. (2004a) treated ripe

green banana (Musa sp., AAA group, Cv. Zhonggang) with 1-methylcyclopropene

(1-MCP) f 1-MCP at 50ml/L significantly delayed the peaks of respiration rate and

ethylene production and retained all the quality attributes during storage.

21

CHAPTER III

EFFECT OF THINNING INTENSITY AND TIMINGS ON

QUALITY FRUIT YIELD OF PEACH




ABSTRACT

Early Grand is one of the early maturning cultivar of peach. Excessive flower and

fruit set on tree, creates a heavy crop load on the tree, which ultimately resulted in

yield and quality losses. So, to minimize crop load and improve the fruit quality, the

present experiment entitled “effect of thinning intensity and timings on the quality

fruit yield of peach” was undertaken at Horticultural Research Farm and Post harvest,

Laboratory, Horticulture Deptt, UAP during the year 2014-15. The experiment was

laid out using two factorial RCB Design with three replicates. Fruits trees were

thinned at different fruit thinning intensities (20, 40 and 60%) at different time (7, 14

and 21 days after 3fruit set). A single control with no thinning was kept for both the

treatment. The experimental results showed that more fruit volume (98.44 cm3), fruit

weight (130.83g), ascorbic acid (5.91 mg 100g-1

), TSS (10.35 0Brix), percent acidity

(0.65%), TSS-acid ratio (22.94) with more split incidence (22.44%) was recorded in

fruit plants received 60% fruit thinning intensity. However, it was statistically at par

with peach fruit trees received 40% thinning intensity. Furthermore, the highest total

yield (80.28 kg) tree-1

was observed in peach fruit plants received 20% fruit thinning

intensity with the production of inferior fruit quality. The thinning intensity of 14 days

after fruit set recorded the highest total fruit yield (77.76 kg) tree-1

, fruit firmness

(5.42 kg cm-2), fruit volume (94.50 cm3), fruit weight (133.11 g), ascorbic acid (5.93

mg 100g-1), TSS (10.09 0brix), percent acidity (0.71%), TSS-acid ratio (22.56), split

pits incidence (21.11%). A significant variation was observed for the interactive effect

of thinning intensity and time for most of the attributes. It is concluded that peach

fruit trees maintained with 40% fruit thinning, 14 days after fruit set could be

preferred for obtaining better quality production.

22

INTRODUCTION

There are many problems related to peach fruits and trees, regarding yield, quality,

pest invasion, etc. Peach fruit is subjected to physical damage and pre harvest

contamination, due to which surface discoloration and other problems may occur

(Crisosto et al., 2000). Many fruit tree species, including peach (Prunus persica L.)

annually produce abundance of flowers that set a surplus of fruitlets which the tree is

unable to support to achieve adequate commercial fruit size. Thinning is necessary to

adjust the number of fruits on a tree so, to obtain the remaining fruits with adequate

size for commercial acceptance (Reighard, 2006). Early competition for

carbohydrates due to heavy flowering can compromise fruit size even when the crop

load is later adjusted to recommended levels (Stover et al., 2001). Therefore, thinning

is accomplished earlier; the greater resources will be available for the remaining fruits.

The effectiveness of the thinning varies with thinning intensity, although the response

also depends on cultivar. Early ripening cultivars are more sensitive to the excessive

load than late-maturing ones and require more intense thinning (Costa and Vizzotto,

2000; Pavel and DeJong, 1993). Thinning provides an optimum leaf-to-fruit ratio

during early spring to ensure good growth of fruits to the maximum size (Meland,

2009). Fruit thinning is now a standard commercial practice, and fruit are most

commonly removed by hand. Hand removal of excess fruit is the most expensive

preharvest activity in peach production, but it is absolutely necessary to produce a

saleable crop.

Keeping in view the importance of thinning intensity, thinning time and its impact on

fruit size, weight and crop productivity, the present experiment was undertaken with

the following objectives.

To optimize the appropriate fruit thinning intensity and timing for better fruit

yield and quality fruit production of peach

To find out the interactive effect of thinning intensity and time for better yield

and quality fruit production of peach

23

MATERIALS AND METHODS

The experiment entitled “Effect of thinning intensity and timings on quality fruit yield

of peach” was carried out at Horticulture Research Farm, The University of

Agriculture Peshawar-Pakistan with objective to optimize the fruit thinning intensity

and thinning time for quality fruit yield of peach cv. Early Grand. The experiment was

carried out by using Ramdomized Complete Block Design (RCBD) with following

two factors replicated three times.

Factors

Factor A Factor B:

Fruit thinning intensity (%) Thinning timings

TI1: Control (No thinning) TT1: 7 days after fruit set

TI 2: 20 TT2: 14 days after fruit set

TI 3: 40 TT3: 21 days after fruit set

TI 4: 60

Thinning procedure: Three unpruned and uniform sized trees of 8 years old for each

treatment were selected for thinning. All the fruits were counted in each tree. Incase of

20% fruit thinninig, 80% of the fruits were retained on the tree and the remaining 20%

were thinned out. Similar procedure was adopted for 40 and 60% fruits respectively.

An average of 1100 fruits was counted on peach trees. To achieve 20% fruit thinning,

880 fruits were retained on the tree while the rest were thinned out. Similarly to

achieve 40 and 60% thinning, 660 and 480 fruits respectively were retained and the

rest of the fruits thinned out. Thinning was practiced with an interval of 7, 14 and 21

days after fruit set.

24

Parameter studied

To study the effect of thinning intensity and timings on quality fruit yield of peach,

the following various attributes were recorded.

Fruit weight (g)

Fruit weight of randomly selected 10 fruits was measured from every treatment in

each replication with the help of digital balance and means were worked out.

Fruit volume (cm3)

Water displacement method was used for determing fruit volume of peach. Fruits

were dipped in one liter graduated beaker. The amount of water displaced was used to

calculate the fruit volume with the help of formula given as under.

Number of fruits kg-1

One kg of fruits were weighed from each treatment and replication and counted the

number of fruits in it and averaged was calculated thereafter.

Fruit yield tree-1

(kg)

The fruit yield (kg) of randomly selected trees was observed with the help of balance

in each treatment and then averages were calculated.

Fruits firmness (kg cm-2

)

Fruit firmness was determined by protocol provided by Pocharski et al. (2000). Using

pressure tester (penotromer), 10 fruits were taken for measuring fruit firmness. Peeler

was used to peel a little part of the peach flesh then the pressure tester inserted until

the tip reach to the soft tissue of the fruit. After reaching, reading was noted, and

averaged firmness was recorded from all treatment and each replication.

Total Soluble solids (0brix)

Total soluble solids (TSS) of peach fruits were measured using hand refractometer

(Kernco, Instruments Co. Texas). Before placing a drop of peach juice the glass prism

of rafractometer wsa cleaned and dried. After placing the drop of peach juice reading

25

was noted for measuring TSS. Glass prism was washed and cleaned with tissue paper

for each reading for getting accurate results.

Percent acidity and ascorbic acid (mg.100g-1

)

Percent acidity and ascorbic acid was determined by neutralization reaction as

described in Iqtidar and Saleemullah (2004)

TSS-acid ratio

The sugar to acid ratio was calculated by dividing the total soluble solids and percent

acidity.

Split/Shattered Pits incidence

Split pits incidence was recorded by extracting the pits from the fruit. The tissues

between the stone and flesh were discarded with the help of spatula and pits were

washed afterwards. The percentage of split pits was determined for each treatment and

average split pit incidence was recorded.

Statistical analysis

The data recorded was arranged according to Randomized Complete Block Design

(RCBD) and was subjected to Analysis of Variance technique as given by Jan et al.

(2009). It was then analyzed using statistical software Statistix 8.1 (Statistix_8

Analytical Software. 2003). In case the data was found significant, least significant

difference (LSD) test was applied for mean comparison.

26

RESULTS

Fruit weight (g)

The statistical analysis of the data showed a significant response of fruit weight to

thinning intensity, time and the interaction between thinning intensity and time was

observed (Table 3.1).

Regarding the means for thinning intensity, the highest fruit weight (130.83 g) was

recorded in fruits trees with 60% thinning intensity, which was statistically at par with

fruit weight (127.94 g) in fruit trees with 40% fruit thinning. The lowest fruit weight

(69.17 g) was noted in control plants (unthinned fruit plants). Regarding the means for

fruit thinning time, heavier fruits (133.11 g) were produced in peach tree thinned after

7 days of fruit set. The lowest fruit weight (116.83 g) was recorded in peach trees

thinned after 21 days of fruit set.

A significant variation was recorded for interaction of fruit thinning and timing

regarding fruit weight. Peach trees with 20% fruit thinning, practiced after 21 days of

fruit set showed poor results for fruit weight (109.83 g). The highest fruit weight

(140.50 g) was recorded in 60% fruit thinning of peach trees, did after 7 days of fruit

set (Fig 3.1).

Fruit Volume (cm3)

The data for fruit volume revealed that thinning intensity and thinning time

significantly affected fruit weight of peach whereas, their interaction was found non

significant (Table 3.1).

The mean data of table showed that increasing intensity of thinning increased the fruit

volume of peach. The maximum fruit volume (98.44 cm3) was recorded in peach trees

with 60% fruit thinning which was statistically at par with fruit volume (96.11 cm3)

recorded in 40% fruit thinned trees. The 20% fruit thinning in peach tree resulted in

lowest fruit volume (74.61 cm3). The fruit volume of 50.83 cm

3 was recorded in

unthinned peach trees. Time of thinning also has a significant effect on fruit volume.

27

The highest fruit volume (94.50 cm3) was observed when fruits were thinned after 7

days of fruit set, while the lowest fruit volume (85.39 cm3) was recorded when fruits

were thinned after 21 days.


The analysis of variance of the data showed that thinning intensity and time

significantly affected number of fruits kg-1

of peach, while their interaction was found

non significant (Table 3.1).

The mean data of table showed that increasing fruit thinning intensity from 20 to 40%

in peach trees decreased the number of fruits kg-1

from 8.85 to 7.75, respectively,

while a further increase in fruit thinning intensity of 60% again decreased the number

of fruits kg-1

to 7.50. This decrease was statistically at par with 40% fruit thinning.

Peach trees where fruit thinning was not performed, produced 14.63 number of fruits

kg-1

. Similarly, regarding the means of thinning time, so all the treatments were

significantly different from one another and earlier to later thinning i.e. 7, 14 and 21

days significantly increased the number of fruits i.e. 7.48, 8.12 and 8.50 respectively

of peach.

Fruit yield tree-1

(kg)

The statistical analysis of the data showed that fruit yield tree-1

was significantly

affected by fruit thinning intensity and thinning time as well as their interaction (Table

3.1).

Computing the means for thinning intensity, keeping a fruit thinning intensity of 20%

produced the highest fruit yield (80.28 kg). The lowest fruit yield (73.97 kg) tree-1

was recroded in fruit trees thinned 60%. Control plants where thinning was not

performed gave fruit yield of 82.00 kg tree-1

.

The fruit yield tree-1

of peach was also significantly influenced by time of thinning.

The highest fruit yield tree-1

(81.27 kg) was noted in peach tress thinned after 21 days

28

of fruit set, followed by fruit yield tree-1

(77.76 kg) recorded in trees thinned after 14

days of fruit set.The lowest fruit yield tree-1

(73.09 kg) was recorded in peach trees

thinned after 7 days of fruit set.

The data for the interactive effect of thinning intensity and time showed that highest

fruit yield (84.83 kg) was observed in trees, thinned 20% after 21 days. The lowest

fruit yield (71.33 kg) was observed in fruit plants with 60% fruit thinning after 7 days

of fruit set (Fig. 3.2).

Split pits incidence (%)

Split pit incidence of peach was significantly affected by thinning intensity, its timing

and their interaction (Table 3.1).

Increasing fruit thinning intensity from 20 to 60% significantly increased the

split/shattered pit incidence from 15.44 to 22.44%. Furthermore, regarding the means

for thinning time, an opposite response in relation to thinning intensity was observed.

Earlier to late thinning i.e. from 7 to 21 days after fruit set significantly decreased

split/shattered pit incidence in peach fruits from 21.11 to 16.33%.

The interaction of thinning intensity and its timing showed that highest split/shattered

pits incidence (24.50%) was recorded in plants with 60% fruit thinning intensity,

thinned after 7 days of fruit set, while the lowest split pits incidence (14.17%) was

obtained from plants where 20% fruit thinning was performed, thinned after 21 days

(Fig 3.3).

29

Table 3. 1: Fruit weight (g), fruit volume (cm3), fruit per kg, fruit yield tree

-1 (kg)

and split pit incidence (%) of peach fruits as affected by thinning

intensity and time.

Fruit thinning intensity

(TI) (%)

Parameters

Fruit

weight (g)

Fruit volume

(cm3)

Fruits

per kg

Fruit yield

(kg)

Split pits

incidence (%)

No Thinning (Control) 69.17 c 50.83 c 14.63 a 82.00 a 9.67 d

20 113.39 b 74.61 b 8.85 b 80.28 b 15.44 c

40 127.94 a 96.11 a 7.75 c 78.88 b 18.22 b

60 130.83 a 98.44 a 7.50 c 73.97 c 22.44 a

LSD (P≤ 0.05) 3.72 2.39 0.33 2.14 0.99

Thinning Time (TT)

7 133.11 a 94.50 a 7.48 c 73.09 c 21.11 a

14 122.22 b 89.28 b 8.12 b 77.76 b 18.67 b

21 116.83 c 85.39 c 8.50 a 81.27 a 16.33 c

LSD (P≤ 0.05) 3.72 2.39 0.33 2.136 0.99

Interaction (TI×TT)

Significance (P≤ 0.05) ** (Fig 3.1) Non Sig. Non Sig. ** (Fig 3.2) ** (Fig 3.3)

Means followed by similar letter(s) in column do not differ significantly from one

another

Non Sig. = Non-significant and *, ** = Significant at 5 and 1% level of probability,

respectively.

30

Thinning Time (DAFS)

7 14 21

Fru

it w

eig

ht (g

)

105

110

115

120

125

130

135

140

145

20

40

60

Fig 3. 1: Fruit weight (g) as affected by interactive effect of thinning intensity and time


7 14 21

Fru

it y

ield

(kg

tre

e-1

)

70

72

74

76

78

80

82

84

86

88

20

40

60

Fig 3. 2: Fruit yield tree-1

(kg) as affected by interactive effect of thinning intensity and time

DAFS stands for days after fruit set

31


7 14 21

Sp

lit p

its incid

ence

(%

)

12

14

16

18

20

22

24

26

28

20

40

60

Fig 3. 3: Split pits incidence (%) of peach as affected by the interactive effect of

thinning intensity and time


32

Fruit firmness (kg cm-2

)


) was significantly affected by thinning intensity and time and

their interaction (Table 3.2).

Increasing fruit thinning intensity from 20 to 60% significantly decreased the fruit

firmness from 5.74 to 5.38 kg cm-2

. Unthinned plants gave the highest fruit firmness

of 6.17 kg cm-2

as compared to rest of the treatments. Furthermore, regarding the

means for thinning time, so an opposite response in relation to thinning intensity was

observed. Earlier to late thinning from 7 to 21 days after fruit set, significantly

increased fruit firmness from 5.42 to 5.72%.

The thinning intensity and time interaction showed that highest fruit firmness (5.88 kg

cm-2

) was recorded in plants with 20% fruit thinning intensity thinned after 21 days of

fruit set, while the lowest fruit firmness (5.15 kg cm-2

) was obtained from plants

received 60% fruit thinning intensity after 7 days of fruit set (Fig 3.4).

Total soluble solids (0brix)

Total soluble solids (TSS) were significantly affected by fruit thinning intensity and

thinning time while their interaction was found non significant (Table 3.2).

Increasing fruit thinning intensity from 20 to 60% significantly increased the TSS

from 9.20 to 10.35 0brix. The TSS of fruit in unthinned plants (control) had 9.93

0Brix.

Furthermore, regarding the means for thinning time, so an opposite response in

relation to thinning intensity was observed. Earlier to late thinning from 7 to 21 days

after fruit set significantly decreased TSS from 10.09 to 9.76 0brix.

Percent acidity

The data for titratble acidity revealed that thinning intensity and time significantly

affected percent acidity of peach whereas, their interaction was found non significant

(Table 3.2).

Significant differences were recorded in all the treatments of thinning intensity. The

peach plants with 20% fruit thining produced the highest percent acidity i.e. 0.71%,

33

while the lowest percent acidity (0.64%) noted in fruit of plants received 60% fruit

thinning.

The fruit of control plants (unthinned) produced 0.71% percent acidity. The fruit of

peach trees thinned after 21 days of fruit set showed the highest percent acidity

(0.74%), while fruits thinned after 7 days of fruit set had the least percent acidity

(0.59%).

TSS-acid ratio

The analysis of variance of the data showed that thinning intensity and its timing

significantly affected TSS-acid ratio of peach fruit, while their interactive effect on

TSS-Acid ratio was found non significant (Table 3.2).

The mean data of Table 3.2 showed that TSS-acid ratio was significantly increased

from 19.17 to 22.94 by increasing fruit thinning intensity from 20 to 60%. The

TSS-acid ratio of 60% fruit thinning was statistically at par with TSS-acid ratio (21.94)

of peach trees with 40% fruit thinning. The fruits of control treatment (Unthinned)

had TSS-acid ratio of 18.5. Similarly regarding the means of thinning time, earlier to

later thinning i.e. 7, 14 and 21 days significantly decreased the TSS-acid ratio i.e.

22.56, 21.83 and 19.67 respectively.

Ascorbic acid (mg 100g-1

)

The data in Table 3.2 shows that ascorbic acid (mg 100g-1

) of peach fruits were

significantly affected by fruit thinning intensity, thinning timings and their interaction

(Table 3.2).

Peach fruit of trees thinned 60%, produced the highest ascorbic acid (5.91 mg 100g-1

)

content, which was statistically at par with ascorbic acid content (5.81 mg 100g-1

) of

fruit in trees with 40% thinning intensity. The lowest ascorbic acid content (5.31 mg

100g-1

) was recorded in fruit of peach plants with 20% fruit thinning practiced. Peach

trees with no thinning (control treatment) showed an ascorbic acid content of 5.27 mg

100g-1

, which was lower than rest of the treatments. Revealing the means for thinning

time, fruits thinned after 7 days of fruit set produced fruits with the highest ascorbic

34

acid (5.93 mg 100g-1

) content, followed by ascorbic acid (5.71 mg 100g-1

) content in

fruits of peach tree thinned after after 14 days of fruit set. Thinning after 21 days of

fruit set gave the lowest ascorbic acid (5.37 mg 100g-1

) content in peach fruits.

The fruit thinning intensity and timings interaction was also found significant. The

highest ascorbic acid content (6.23 mg 100-1

) was recorded in fruits plants with 40%

fruit thinning, after 7 days of fruit set. The lowest ascorbic acid content (5.31 mg

100g-1

) was observed in fruits obtained from trees with 20% thinning intensity, after

21 days of fruit set (Fig 3.5).

Table 3. 2: Fruit firmness (kg cm-2

), total soluble solids (°brix), percent acidity,

TSS-acid ratio and ascorbic acid (mg.100g-1


by thinning intensity and time

Fruit thinning

intensity (TI)

(%)

Parameters

Fruit

Firmness

(kg cm-2

)

Total Soluble

Solids (0Brix)

Percent

acidity

TSS-Acid

Ratio

Ascorbic acid

(mg 100g-1

)

No Thinning 6.17 a 8.22 d 0.71 a 18.5 b 5.27 b

20 5.74 b 9.20 c 0.71 a 19.17 b 5.31 b

40 5.60 c 10.24 b 0.65 b 21.94 a 5.81 a

60 5.38 d 10.35 a 0.64 b 22.94 a 5.91 a

LSD (P≤ 0.05) 0.04 0.075 0.026 2.09 0.124

Thinning Time (TT)

7 5.42 c 10.09 a 0.59 c 22.56 a 5.93 a

14 5.58 b 9.94 b 0.66 b 21.83 a 5.71 b

21 5.72 a 9.76 c 0.74 a 19.67 b 5.37 c

LSD (P≤ 0.05) 0.041 0.075 0.026 2.09 0.124

Interaction (TI×TT)

Significance

(P≤ 0.05) *** (Fig 3.4) Non Sig. Non Sig. Non Sig. ** (Fig 3.5)


35

another

Non Sig. = Non-significant and *, ** = Significant at 5 and 1% level of probability,

respectively.


7 14 21

Fru

it fir

mne

ss (

kg

cm

-2)

5.0

5.2

5.4

5.6

5.8

6.0

20

40

60

Fig 3. 4: Fruit firmness of peach as affected by the interactive effect of thinning

intensity and time



7 14 21

Asc

orb

ic a

cid

(m

g 1

00

g-1

)

5.0

5.2

5.4

5.6

5.8

6.0

6.2

6.4

20

40

60

Fig 3.5: Ascorbic acid (mg 100g-1

) of peach as affected by the interactive effect of thinning

intensity and time


36

DISCUSSION

Fruit yield and yield related attributes with split pit incidence

A complex relationship between shoot and root system is observed during the growth

and development of peach plants. The demand for carbon and energy is met by the

plants through the photosynthates produced by the leaves during the process of

photosynthesis, which is responsible for new tissues formation (Taiz and Zeiger,

2006). The photosynthates produced create a competition between the fruits and roots

during growth and development of plants. Developing fruit and roots compete with

each other for assimilates produced in leaves (Marcelis et al., 2006). Source and sink

relationship directly or indirectly affects the development of organs and

photosynthetic activity. So, balanced photosynthates partitioning is very important for

proper growth and development of fruits, which indirectly affects the yield of a crop

(Max et al., 2016). Fruit weight was increased by 85% with 40% fruit thinning. The

increase was higher (89%) with more split pit incidence at 60% (45%) fruit thinning

than 40% thinning practiced. It is obvious from this study that, thinning reduced the

number of fruits, which positively affects the overall sink strength of the generative

organs and assimilates competition between fruits. All these factors increased the fruit

weight (Table 3.1). Thinning is the best option to optimize the assimilate portioning

between fruits by decreasing the number of fruits and increasing fruit weight. The

major objective of fruit thinning is to optimize the fruit to leaf ratio in peach

(Sansavini et al., 1985). Fruit thinning helps in better utilization of the light in the

canopy thus helping in photosynthesis process and producing large sized and heavy

weight fruits (Chartzoulakis et al., 1993; Tustin et al., 1992 and Westwood, 1993).

Fruit volume was increased by 89% with 40% fruit thinning which is less than 94%

achieved with more split pit incidence (45%) at 60% fruit thinning as compared to

40% fruit thinning (18% split pit incidence). A decrease of 47 and 5% in number of

fruits kg-1

and fruit yield with 40% fruit thinning was observed. The difference in the

above attributes was higher (49 and 10% respectively) but with more split pit

37

incidence (45%) at 60% fruit thinning than 40% fruit thinning (18% split pit

incidence). As already mentioned there was a complex relationship between shoot and

root system during the growth and development of plants. It is obvious from the

present study that thinning reduced the number of fruits, which positively affects the

overall sink strength of the generative organs and assimilates competition between

fruits. All these factors increased the fruit weight (Table 3.1).

Zayan (1991) also showed that pruning severity significantly increased the fruit size,

weight and yield of peach. Bussi et al. (2005) were also of the opinion that optimizing

fruit load in early maturing peach cultivars produced fruits of larger size and weight.

In an another study, Bussi et al. (2009) also reported that thinning produced fruits of

superior quality and positively affects the weight, size and yield of peach. Mikhael et

al. (2012) found that, dormant pruning of peach tree increased fruit size and weight

accordingly.

The present data showed that increasing thinning intensities significantly decreased

the number of fruits. The increase in fruit volume due to thinning might be due to the

better utilization of the photosynthates that might not be utilized, if the number of

fruits on the tree is high (Table 3.1). Thus, less number of fruits resulted in the

efficient utilization of the photosynthates, hence resulted in increased fruit volume

and weight (Table 3.1). Furthermore, previous studies showed that optimum thinning

proved to be better in improving fruit size and volume without any effect on fruit

yield (Naor et al., 1999). Although thinning decreased fruits number but it increased

fruit size that could restore the yield losses (Rettke, 2005). Costa and Vizzotto (2000)

also reported that fruit thinning may interfere, the supply and demand of

carbohydrates. In heavy crop load, the demand is more as compared to the supply,

hence, undesirable competition between the fruits and other organ occurs. Therefore,

optimum thinning regulates the supply and demand to fruits in an optimum way that

results in increased fruit size, volume and yield.

The present results are in similarity with the results of Samuel and Goregory (2008)

38

who reported a significant increase in fruit diameter as fruit spacing was increased.

Moreover, the present results are in close conformity with the results of those

presented by Zayan (1991); Bussi et al. (2005); Bussi et al. (2009) and Mikhael et al.

(2012) who reported that increased thinning and decreasing the fruit load on tree

significantly increased fruit size and weight of peach. Moreover, hand thinning

significantly increased fruit volume and weight as well as TSS of peach fruits (Babu

and Yadave, 2004; Son, 2004).

The present data showed that increasing thinning intensities significantly decreased

the number of fruits. The increase in fruit volume due to thinning intensity might be

due to the better utilization of the photosynthates that might not be utilized, if the

number of fruits on the tree is high (Table 3.1). Thus, less number of fruits resulted in

the efficient utilization of the photosynthates, hence, resulted in maximum fruit

volume and weight (Table 3.1). Furthermore, previous studies showed that optimum

thinning proved to be better in improving fruit size and volume without any effect on

fruit yield (Naor et al., 1999). Although thinning decreased fruits number but it

increased fruit size that could restore the yield losses (Rettke, 2005). Costa and

Vizzotto (2000) also reported that fruit thinning may interfere the supply and demand

of carbohydrates. In heavy crop load, the demand is more as compared to the supply,

hence undesirable competition between the fruits and other organ occurs. Therefore,

optimum thinning regulates the supply and demand to fruits in an optimum way that

results in increased fruit size, volume and yield. All thinning treatments decreased

fruit number per tree compared to the untreated control. This might be due to the fact

that thinning treatment basically reduces the crop load on the plant and optimizes the

fruit to leaf ratio that ultimately lead to better fruit yield. Balancing of fruit to leaf

ratio by fruit or flower thinning treatment, results in flower bud formation and growth

of shoots (Byers and Lyons, 1985; Myers, 1986; Corelli and Coston, 1991).

The present results are in similarity with the results of Samuel and Goregory (2008)

who reported a significant increase in fruit diameter of peach as fruit spacing was

39

increased. Moreover, the present results are in close conformity with the results of

those presented by Zayan (1991); Bussi et al. (2005); Bussi et al. (2009) and Mikhael

et al. (2012) who reported that increased thinning and decreasing the fruit load on tree

significantly increased fruit size and weight of peach. Moreover, hand thinning

significantly increased fruit volume and weight as well as TSS of peach fruits (Babu

and Yadave, 2004; Son, 2004).

The factors recognized for the deterioration of fruit quality and reduction of

marketable yield (Mutwiwa et al., 2008) is poor fruit set and high numbers of

undersized fruits (Liebisch et al., 2009; Max and Horst, 2009). Hence, in the present

study it had been found that fruit thinning is a simple and inexpensive method to

maneuver the source-sink relationship in peach fruit that overcome the heavy crop and

fruit load on the tree. Assimilate partitioning in the sink largely depends on the

strength of the source, sink and assimilate availability unless and until light is limiting

(Heuvelink, 1995; Ho, 1996). During the reproductive growth stage, the fruits

represent the strongest sinks among the organs (Cockshull and Ho, 1995). The overall

sink strength of the gerenative organs and competition between individual fruits for

the photoassimilates are improved by thinning and pruning. Thus, maintaining a

proper fruit to leaf ratio, positively affects in heavy fruit yield (Samira et al., 2014),

which greatly confirms the present results. Moreover, reducing fruit load positively

affects fruit quality as well (Hesami et al., 2012). An option for optimizing

carbohydrates and assimilates partitioning between the fruit and leaves decrease the

undesired fruits and improve the fruit yield by producing heavy fruits (Max et al.,

2016).

Fruit thinning helps to produce an optimum size of better quality fruits and thus gains

higher prices in the market. The fruit yield decreased with increasing the thinning

intensity but overall production was compensated by better sized quality fruit

production and fetch high price in the market. The increment in individual fruit

accompanied with more fruit weight compensates the yield losses due to thinning

40

(Rettke, 2005). The present study, also noticed that the fruit size and weight was

considerably increased with better quality attributes (Table 3.1).

As hand thinning is a tedious labor-intensive but still the only safe way to balance the

availability of the food reserves to the fruit. This results in good source-sink

relationship which ultimately led to increase the fruit size and yield (Byers and Lyons,

1983). Increase in size and weight is negatively correlated with fruit number.

Thinning treatment basically reduced the number of fruits thus allowing more

nutrients to be available for each fruit hence size, weight and yield increased with

reduction in fruit number (Chunk et al., 2001; Naor et al., 1997). Fruit thinning

basically reduced and prevented the energy and nutrients that might be drained by pits

for its development and hence the physical nature and quality of fruits (Peter and

Abraham, 2007). The results of Babu and Yadave (2004) are of prime importance,

who reported that hand thinning peach trees significantly reduced fruit drop and fruit

number, thus ultimately increased the fruit size and weight resulted in more yield. The

timing of thinning is also important. This is basically due to the fact that early

thinning gave more time to the fruits to utilize the carbohydrates and food reserves

which would otherwise, not be properly utilized in late thinning (Wardlaw, 1990). In

this study, thinning time of day 14 recorded an increase of 77 and 76% in fruit weight

and fruit volume while a decrease in 44% and 05% in number of fruits per kg and

fruit yield as compared to day 21 (23% split pit incidence) where the difference was

more but an incidence of more split pits. Hence 40% fruit thinning after 14 days (12%

split pit incidence) of fruit set is appropriate for more yields, good sized peaches with

minimum split pits. If fruits thinning were not practiced at an appropriate time would

lead to disturb the physiology of the crop (Southwick et al., 1995). Many studies have

shown that thinning during or soon after bloom increased final fruit size (Byers and

Lyons 1984; Costa and Vizzotto. 2000), as compared with late thinning (Pavel and

DeJong, 1993).

The results are in correlation with the results of Mohsen (2010) who reported that fruit

41

thinning 20 days after full bloom at 20 cm apart significantly reduced the fruit number

and improved the quantitative and qualitative attributes of peach fruit. The present

results are in close conformity with the Samira et al. (2014) who reported that a

balanced fruit to leaf ratio produced better yield in thinning of peach trees.

Furthermore, Li et al. (2015) also reported that balance of source and sink ratio in

tomato plant organ positively correlated with fruit size and yield. Deshmukh et al.

(2012) also reported that an optimum fruit to leaf ratio of 45:1 is suitable for

maintaining fruit yield in peach.

Split pits incidence is a major problem in peach canning industry during processing of

fruits (Drogoudi et al., 2009). In addition, it also adds to the cost as when consumers

can not consume it properly. It is reported that it appears 2-4 weeks after pit

hardening, when lignin is formed in both the halves of the pits. The incidence of split

pits is a cultivar-specific characteristic (O’Malley and Proctor, 2002) as early peach

varieties are most susceptible to split pits incidence. Previous researches shown that

split pits incidence is related to growth rate of the peach fruit (Monet and Bastard,

1979). The incidence of split pits can also be due to the girdling of lateral branches of

peach. Generally the cultural practices like thinning, good nutritional program and

irrigation which are done normally enhances the fruit size but increases the level of

shattered pits and split pits (Beppu and Kataoka, 1999). The reason behind this might

be enhanced photosynthetic carbon-partitioning to the fruit (Kubota et al., 1993). The

present results also showed that split pits incidence was observed in heavily thinned

fruit trees as compared to lightly or moderately thinned fruit tees (Table 3.3). Early

thinning also results in severe problem of split pits as compared to late thinned fruit

trees. Early thinning, before pit hardening, also increased the incidence of split pits,

probably because the fruit were at a more sensitive stage of growth, which made them

more prone to pit splitting (Drogoudi et al., 2009). The present results are in close

conformity with Monet and Bastard (1979) who reported that reduced crop load

results in split pit incidence in peaches. In addition, Drogoudi et al. (2009) also

42

observed split pit incidence in heavily thinned trees as compared to lightly or

moderately thinned trees. Furthermore, Byers and Marini (1994); Ebel et al. (1999)

and Greene et al. (2001) also reported that the various levels of thinning intensities

resulted in split pits incidence and adversely affects the productivity of peach.

Fruit quality attributes

Total soluble solids, TSS-acid ratio and ascorbic acid were increased by 25, 19 and

10%, respectively and a decrease of 9 and 8% in fruit firmness and percent acidity

respectively occurred in fruits of trees subjected to 40% fruit thinning. The difference

in the quality attributes of peach fruit (Total soluble solids, TSS-acid ratio, ascorbic

acid, fruit firmness and percent acidity) was higher (26, 24, 12% and 13, 10%

respectively) in fruits of trees received 60% thinning intensity but resulted in more

percent of split pit incidence (23%) (Table 3.2) as compared to fruits of trees had 40%

thinning intensity.

The peach fruit thinned after 14 days of fruit set revealed an increased percentage of

21, 18 and 8 of total soluble solids, TSS-acid ratio and ascorbic acid respectively with

a gradual decline of 10 and 7% noted in fruit firmness and percent acidity with

minimum split pit induction i-e 12%. However, the more split pit incidence (23%)

was recorded in fruit thinned after 21 days of fruit set as compared to 40% fruit

thinning after 14 days of fruit set with 12% split pit incidence (Table 1).

The quality of the fruits is greatly affected by fruit position along the canopy, distance

from tissue source and proximity to other sinks (Caruso et al. 2001; Forlani et al.

2002; Gugliuzza et al. 2002), shoot type (Corelli et al. 1996) and leaf-to-fruit ratio

(Wu et al. 2005). The present study showed that decreasing crop load significantly

increases the fruit firmness of peach (Table 3.2). Furthermore, firmness decreased

with increase in fruit size (Von Mollendorg et al., 1992). This might be due to the fact

that increased fruit size increased the total soluble solid contents which results in less

firmer fruits. Previous studies also showed that thinning results in softening of fruits

due to increased amount of enzymatic activities (Gardner et al., 2000). The decrease

43

in fruit firmness under thinning treatments might be due to higher accumulation of

nitrogen in the fruit resulting in fruit softening via activation of cell wall softening

enzymes (Farina et al., 2006). Moreover, an increase in fruit weight during the last

stage of fruit ripening rapidly decreased the fruit firmness which is confirmed by the

data of this research. This might also be due to the accumulation of sugars (Farina et

al. 2006; Ramina et al. (2008). The variation in fruit firmness in relation to fruit

weight might also be due to the difference in fruit ripening that depends on the

availability of light to the plant and fruit density (Genard and Bruchou 1992; Caruso

et al., 2001; Forlani et al., 2002). In the present study, the reduction in fruit firmness

due to heavy thinning (Table 3.2) might also be due to the decrease strength of cell

wall and less cohesion between the cells as a result of increase fruit size (Deshmukh et

al., 2012). The present findings are in close conformity with the findings of Saini et al.

(2003) who suggested that fruit firmness was significantly reduced by hand thinning

done just before pit hardening stage in peach. The present results are also confirmed

by many researchers that decreased crop load decreased fruit firmness in kiwi fruit

(Babita and Rana, 2015), peaches (Saini et al., 2003; Trevisan et al., 2000; Meitei et

al., 2013; Casierra et al., 2007; Kaur, 1997) and plum (Lata et al., 2014). Furthermore,

Patel et al. (2014) recommended 30:1 leaf to fruit ratio for improving the yield and

yield related attributes in peach fruits with a decrease in fruit firmness.

The present results also showed that increasing thinning significantly improved the

total soluble solids of peach fruit. Total soluble solids were increased in fruit by 25%

with 40% fruit thinning with less quantity of split pit incidence i-e 23%. However, the

higher content of TSS (26%) with more split pit incidence (45%) recorded in fruits

obtained from trees subjected to 60% fruit thinning (Table 3.2).

This might be due to the higher rate of photosynthate assimilation (Patel et al., 2014),

advancement of fruit ripening stage with the production of more ethylene (Lotter,

1991; Lawes et al., 1991; Patterson et al., 1994; Costa et al., 1995). Furthermore,

increase in TSS content might be attributed to reduce crop load due to thinning of

44

young fruitlets, resulted in more synthesis, transport and accumulation of sugars and

photosynthate in the remaining fruits (Patel et al., 2014). The suppression of

assimilates resulted in more assimilates availability for fruit growth that advanced the

maturity and increased the fruit size (Day and DeJong, 1990). Generally, assimilate

supply is dependent on photosynthesis (Marschner, 2012). The amount and pattern of

plant growth and yield is determined by the partitioning of the carbohydrates. Whereas,

translocation of assimilates and other metabolites greatly depends on growth stage and

fruit development process of plant (Lakso and Flore, 2003). Due to the position and

strength of the sink affects the transport directions and volume of assimilates (Friedrich

et al., 2000). The differential use of carbohydrates in metabolism, transport and storage,

synthesizes and stores starch within the chloroplasts during the night (Taiz and Zeiger,

2006) that are transferred to the fruit by leaf photosynthesis and carbohydrates reserves

(Friedrich et al., 2000). This in turns rapidly accumulates the total soluble solids in the

fruits (Zufferey et al., 2012). The thinning intensity increased the TSS in fruit of apple

(Forshey and Elfving, 1989) and peach (Davis and Davis, 1948) which greatly

confirmed the present results (Table 3.2). Furthermore, decreased crop load

management significantly increased the fruit TSS with decreased in fruit firmness of

kiwi fruit (Casierra et al., 2007). Also, Chanana et al. (1998) and Saini and Kaundal

(2003) reported that highest TSS of peach fruits were obtained with hand thinning.

The results of Deshmukh et al. (2012) are of prime importance. They concluded

that keeping leaf to fruit ratio of 45:1 produced the highest TSS in peach as

compared to control and other ratios.

A major factor behind fruit growth and quality in peaches is the crop load

management (Blanco et al., 1995; Marini and Sowers, 1994; Volz et al., 1993). The

basic objective of thinning is to optimize the leaf-to-fruit ratio (Sansavini et al., 1985).

Different factors may influence fruit size and quality. Flowers and fruits act as

powerful sinks for carbohydrates (Marcelis, 1996). The reason for the decline in

acidity with increasing intensity of thinning might be due to the increased in

45

membrane permeability, where the stored acids are respired (Kliewer, 1971) resulting

in production of malic acid salts, translocation of acids into sugars (Hardy, 1968).

These factors led to the production and buildup of sugars and hence the volume of the

fruit increased and acidity of the fruit decreased. Another reason might be the buildup

of sucrose (which represents over 95% of the dry weight), translocated in the sieve

tubes of the phloem (Kozlowski and Pallardy, 1997) to the developing fruits which is

only possible with the expanse of organic acids (Kaur, 1997). Starch, the most

common and important storage form of carbohydrates, is the most useful indicator of

seasonal carbohydrates trends in the tree crop, which indicates the tree performance

(Wolstenholme and Whiley, 1989). Starch accumulation is only possible, if there are

high levels of sugar buildup. Sugar buildup is only possible if there are organic acids

in the fruit. In thinning treatments, the fruit gain size and weight (Table 3.2) due to the

accumulation of carbohydrates and this is only possible due to the expanse of organic

acids (Kozlowski and Pallardy, 1997). This is the reason that during thinning, the

organic acid decreased and buildups of sugars occurs which greatly confirms the

results of the present study (Table 3.2). Thinning significantly reduced the acid

content and increased the TSS of the kiwifruit as reported by Park and Park (1997);

Chahill et al. (1980). These findings also get support from Kaur (1997) and Saini et al.

(2003) who reported a reduction in acidity of peach by hand thinning when done

before pit hardening stage.

The present results showed that with increase in thinning intensity significantly

increased the TSS-acid ratio (Table 3.2). This might be due to the fact that the quality

of fruits can be determined by TSS-acid ratio. High quality fruits have high TSS and

low acids; this might be due to the fact that thinning basically reduces the inter-fruit

competition which results in high amount of carbohydrates accumulation in the fruit

(Link, 2000) which resulted in an increase in TSS-acid ratio (Table 3.2). Sweet taste

of fruits is due to the high ratio of TSS and acids and thus contributed to the taste in

stone fruits (Rab et al., 2012). The increase in TSS-acid ratio might be due to the

46

increase in TSS and decrease in acidity which tends to increase the TSS-acid ratio

(Table 3.2). The present results are in close conformity with Chanana et al. (1998) and

Abd El-Megeed (2001) who observed that hand thinning of fruit and flower

significantly increased the TSS, TSS-acid ratio, ascorbic acid but decrease the acidity

of peach.

Ascorbic acid is an important nutritional component of fruits that provides protection

against various chronic diseases related to oxidative stress (Mark et al., 2002). The

present result showed that thinning results in the increase in the ascorbic acid content

of the fruit which shows the significance of thinning that it not only increases the fruit

size and weight but also improves the quality of fruit as well (Chanana et al., 1998).

The present results are greatly confirmed by Deng et al. (1997) and Link (2000) who

reported increased ascorbic acid content of peach due to girdling and thinning

treatments, respectively.

47

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

Summary

The experiment was carried out at Horticulture Research Farm, The University of

Agriculture Peshawar with an objective to find out the optimum thinning intensity and

timing of thinning for fruit yield and quality of peach cv. Early Grand. The

experiment was carried out by using Randomized Complete Block Design (RCBD)

with two factors factorial arrangement replicated three times. The experiment

comprised of three thinning intensity i.e. 20, 40 and 60 with three thinning time (7, 14

and 21 days after fruit set). A single control was kept for all the treatments where no

thinning was performed. Three trees were assigned to each treatment.

Different growth, yield and quality attributes were studied like fruit weight (g), fruit

volume (cm3), number of fruits kg

-1, fruit yield tree

-1 (kg), fruits firmness (kg cm

-2),

total soluble solids (°brix), percent acidity (%), TSS-acid ratio, ascorbic acid (mg 100

g-1

) and split/shattered pits incidence (%).

The statistical analysis of the data showed that thinning intensity, time significantly

affected most of the attributes. Less number of fruits kg-1

(7.50), fruit yield (73.97 kg),

fruit firmness (5.38 kg cm-2

), percent acidity (0.64%) more fruit volume (98.44), fruit

weight (130.83 g), ascorbic acid (5.91 mg 100g-1

), TSS (10.35 0brix), TSS to acid

ratio (22.94), split incidence (22.44%) was recorded in tree with fruit thining intensity

of 60%. While more number of fruits kg-1

(8.85), fruit yield (80.28 kg), fruit firmness

(5.74 kg cm-2

), less fruit volume (74.61), fruit weight (113.39 g), ascorbic acid (5.31

mg 100g-1

), TSS (9.20 0brix), percent acidity (0.71%), TSS to acid ratio (19.17) and

split incidence (15.44%) was recorded in tree with 20% fruit thinning.

Regarding thinning time, earlier thinning i.e. 7 days after fruit set recorded less,

number of fruits kg-1

(7.50), fruit yield (14.45 kg), fruit firmness (5.42 kg cm-2

),

percent acidity (0.74%), more fruit volume (94.50 cm3), fruit weight (133.11 g),

ascorbic acid (5.93 mg 100g-1

), TSS (10.09 0brix), TSS to acid ratio (22.56), split

incidence (21.11%). While more number of fruits kg-1

(8.50), fruit yield (20.67 kg),

48

fruit firmness (5.72 kg cm-2

), percent acidity (0.59%), less fruit volume (85.39 cm3),

fruit weight (116.83 g), ascorbic acid (5.37 mg 100g-1

), TSS (9.76 0brix), TSS to acid

ratio (19.67), split incidence (16.33%) was recorded in fruits thinned after 21 days of

fruit set.

Conclusions

Based on the present results the following conclusions can be made

Peach fruit trees with 60% fruit thinning showed better response to most of the

studied attributes but decreased the fruit yield and increased the split pit

incidence in peach.

Although, 20% fruit thinning intensity increased the yield and decreased the

split pit incidence but decrease the fruit weight and quality of peach fruits

The fruit yield and reduction in split pits of peach recorded in fruit plants with

20% fruit thinning, were statistically at par with 40 fruit thinning intensity

Earlier thinning i.e. thinning after 7 days of fruit set responded well to all the

yield related and quality attributes of peach with more split pits incidence

Thinning after 14 days of fruit set increased the fruit yield and improved other

quality attributes of peach

Recommendations

The following recommendations are made on the basis of the conclusions

Peach fruit trees with 40% fruit thinning are recommended to produce quality

fruit yield of peach cv. Early Grand

The fruit thinning i.e. 14 days after fruit set could be recommended to the

growers of Khyber Pakhtunkhwa to obtain quality fruit yield of peach cv.

Early Grand

49

CHAPTER IV

INFLUENCE OF IRRIGATION INTERVALS AND GIBBRELLIC

ACID ON SPLIT PIT INCIDENCE AND FRUIT QUALITY OF

PEACH




ABSTRACT

Split pits incidence is one of the physiological disorders in early ripening cultivars of

peach. It is mainly concerned with heavy thinning, fluctuation of weather conditions

and hormonal regulation. In order to overcome the problem, the present study entitled

“Influence of irrigation intervals and gibbrellic acid (GA3) on split pits incidence and

fruit quality of peach” was undertaken at Horticultural Research Farm and

Post-harvest Laboratory, Department of Horticulture, The University of Agriculture

Peshawar-Pakistan during the year 2014-15. The experiment was undertaken using

Randomized Complete Block Design with split plot arrangement having three

replicates. The irrigation intervals were kept in main plots and GA3 subjected to

subplots in order to collect the experimental data. Irrigation management (5, 10 and

15 days) and GA3 (0,50, 100 and 150 ppm) was applied to the fruits of peach plants

with thinning intensity (40%) and its timing (after 14 days of fruit set) optimized from

the previous year experiments (2014). The experimental results showed that highest

leaf area (27.40 cm2), fruit weight (129.33 g), fruit volume (95.25 cm

3), fruit yield

(74.50 kg), firmness (5.57 kg cm-2

), less number of fruits (7.92), split pit incidence

(7.96%) and TSS (8.19 °brix) were recorded in fruit trees irrigated after every 10 days.

As concerned the effect of gibbrellic acid, more fruit weight (129.61 g), fruit volume

(93.33 cm3), fruit yield (74.56 kg), fruit firmness (5.44 kg cm

-2), lower total soluble

solids (8.05 °brix) were recorded when trees sprayed with 100 ppm GA3, while the

lowest number of fruits (7.77) kg-1

and split pits incidences (8.05%) were recorded in

fruits trees treated with 150 ppm GA3 solution. The interactive effect of irrigation

intervals and gibbrellic acid on all the studied attributes was found non-significant. It

is concluded from the experiment that peach fruit trees could be irrigated after every

10 days and sprayed with 100 ppm GA3 to overcome the problem of split pits

incidence in peach trees cv. Early Grand and also to obtain the optimum fruit yield of

better quality

50

INTRODUCTION

It has been known that split pits occur more severely in early ripening peach cultivars

(Byrne et al., 1991) being more susceptible to this disorder as pit hardening and final

swell phases of fruit development occur relatively close together. Final swell for early

ripening cultivars occurs before the adherence between the pit and the flesh. Therefore,

the expansion of the fruit flesh creates internal forces pulling on the pit. If great

enough, this force will cause the pit to break in the weakest spot along the suture. In

fruits with split pits, the pits are broken in several places and the pit cavity may

contain a gummy substance (Barcelon et al., 1999).

Split-pits incidence is more common problem but our understanding of this

phenomenon is still limited. In general, cultural practices that enhanced fruit size

(thinning, good nutrition, irrigation), increase the level of split pit of peach fruits.

However, recent studies suggested that girdling may enhance fruit size and yield

appreciably aggravating the well-known split pit problem of certain peach varieties

(Engin et al., 2010).

Peach fruits with split pits are unmarketable, although can be removed by hand

thinning and sorting at the expense of considerable yield loss (Patten et al. 1989).

Some peach cultivars may have 40-70% double fruits and split pits. These disorders

are increased by the climate and management practices like irrigation, fertilization and

hormonal activities. Moreover, certain varieties are more predisposed to a specific

disorder (Engin et al., 2010). In recent years, the effect of these stress factors on split

pits incidence of fruits has also been investigated. Deficient and over irrigation during

the summer (Patten et al. 1989; Larson et al., 1988 and Johnson et al., 1992)

increased the development of double fruits and split pits in peach, respectively. The

effects of water stress during the final stage of rapid fruit growth were also shown to

be more decisive in terms of fruit quality, notably by decreasing fruit size and

increasing total fruit soluble solids (Li et al., 1989; Bussi et al. 1999; Besset et al.

2001).

51

Split pits incidence might be related to unbalanced nutritional management and

unavailability of hormones. Gibberellic acid (GA3) is known to inhibit flower bud

differentiation in deciduous fruits (Beppu and Kataoka, 1999) and its application

during the flower bud differentiation period reduced flowering and increased fruit size

with a reduction in physiological disorders especially split pits in stone fruits (Taylor

and Taylor, 1998).

Keeping in view the economic importance of split pits in early ripening peach

cultivars, the present experiment was conducted with the following objectives.

To study the influence of irrigation intervals to reduce the incidence of split

pits for quality fruit production of peach

To find out the most appropriate concentration of gibbrellic acid to reduce split

pit incidence and enhance the fruit quality of peach

To study the interactive effect of irrigation intervals and gibbrellic acid on split

pit incidence and quality fruit production peach

52


The experiment was carried out at Horticulture Research Farm, The University of

Agriculture Peshawar during the year 2015 with the objectives to manage the

irrigation intervals and optimize the gibbrellic acid concentration for improving fruit

quality and reducing split pits incidence in peach cultivar Early Grand.

Peach fruits were thinned during the year 2014 at various intensities (20, 40 and 60%)

at 7, 14 and 21 days after fruit set. Results of the experiment showed that 40% fruit

thinning practiced after 14 days of fruit set showed more split pit incidence in peach

fruits. To overcome this problem, sequential experiment was planned during 2015.

Optimized fruit thinning intensity (40%) and thinning time (14 days after fruit set)

were kept constant in all fruit trees and irrigated at various intervals with foliar

application of gibbrellic acid at various concentrations. This experiment was carried

out by using Randomized Complete Block Design (RCBD) with split plot

arrangement replicated three times. The experiment consisted of 3 irrigation intervals

assigned to main plots along with 4 levels of foliar application of gibbrellic acid

subjected to sub plots, the details of the factors are given as under.

Factors

Factor A: Irrigation intervals Factor B: Gibbrellic acid concentration (ppm)

I1: 5 days G1: Control

I2: 10 days G2: 50

I3: 15 days G3: 100

G4: 150

Irrigation management

Peach trees were properly irrigated with double furrow irrigation at 5, 10 and 15 days

intervals. In case of any accidental rainfall or cloudy weather, the ground was

protected with transparent polythene sheets to cover the soil below and around the

tree canopy (Haq, 2011).

53

Preparation of Gibbrellic acid concentration

Different concentrations of gibbrellic acid i.e. 50, 100 and 150 ppm were prepared.

For preparing 50 ppm GA3 solution, 50 mg of GA3 was taken and dissolved in a little

volume of alcohol (5-10ml) and heated to improve the solubility. After dissolving, the

solution was put in water and raised the volume to 1L. Similar procedure was used for

preparing 100 and 150 ppm of GA3 solution.

Mean monthly maximum and minimum rainfall and precipitation

2014

Feb Mar Apr May

Tem

pera

ture

oC

0

10

20

30

40

2015

Feb Mar Apr May

Rai

nfal

l (m

m)

0

100

200

300

400

500

600Max. Temp

Min. Temp

Rainfall

Fig I: Total monthly rainfall (mm), minimum and maximum temperature (oC) of the

experimental area from February to May during 2014 and 2015

To study the effect of gibbrellic acid and irrigation interval on reducing split pit

incidence and quality fruit yield of peach, the following various attributes were

recorded

Leaf area (cm2)

Leaves from randomly taken three peach trees from each treatment in each replication

were measured with the help of leaf area meter and average was worked out.

The procedures for the determination of fruit weight (g), fruit volume (cm3), number

of fruits kg-1

, fruit yield tree-1

(kg), split pits incidence (%), fruit firmness (kg cm-2

),

54

total soluble solids (°brix) were followed given in experiment 1 (Chapter 3).


The data recorded was arranged according to Randomized Complete Block Design

with split plot arrangement. The data was subjected to Analysis of Variance technique

as given by Jan et al. (2009). It was then analyzed using statistical software Statistix

8.1 (Statistix_8 Analytical Software, 2003). In case the data was found significant,

least significant difference (LSD) test was applied for mean comparison.

55

RESULTS

Leaf area (cm2)

The data for leaf area of peach leaves showed that leaf area was significantly

influenced by irrigation intervals (II), whereas the effect of gibbrellic acid (GA3) and

its interaction with irrigation intervals was non-significant (Table 4.1).

The highest leaf area (27.40 cm2) was noted in peach fruit trees irrigated after 10 days

as compared to the leaf area (25.00 and 23.00 cm2) recorded in peach trees irrigated

after 5 and 15 days respectively.

Table 4. 1: Leaf area (cm2) of peach as affected by irrigation intervals and

gibbrellic acid concentrations (ppm).

Gibbrellic acid

(ppm)

Irrigation intervals (Days)

Mean 5 10 15

Control 24.67 26.67 22.33 24.56

50 25.00 27.00 23.00 25.00

100 25.33 28.00 23.67 25.67

150 25.00 27.83 23.00 25.28

Mean 23.00 c 27.38 a 25.00 b

LSD for irrigation intervals at P≤0.05: 1.80

Means followed by similar letter(s) are statistically at par at 5% level of significance

Fruit weight (g)

Irrigation intervals (II) and gibbrellic acid (GA3) significantly affected fruit weight of

peach whereas a non-significant variation was recorded for their interaction (Table

4.2).

The maximum fruit weight (129.33 g) was produced by peach fruit trees irrigated

after 10 days, while the minimum fruit weight (127.50 and 123.00 g) was recorded in

peach fruit trees irrigated after 5 and 15 days of interval respectively.

Increasing GA3 concentration from control to 100 ppm significantly increased the

fruit weight from 123.39 to 129.61 g while a further increase in GA3 concentration i.e.

150 ppm decreased the fruit weight (125.83 g) of peach.

56

Fruit volume (cm3)

The analysis of variance showed that the irrigation intervals (II) and gibbrellic acid

(GA3) significantly influenced the fruit volume of peach, whereas their interaction

was found non-significant for fruit volume of peach (Table 4.2).

As concerned irrigation intervals, the highest fruit volume (95.25 cm3) was taken from

peach fruits trees irrigated after 10 days interval, which was statistically different from

the rest of the treatment, followed by fruit volume (93.67 cm3) in peach fruits trees

irrigated after 5 days interval. The lowest fruit volume was observed in peach fruits

trees irrigated after every 15th

day.

The mean data for gibbrellic acid showed that the fruit volume of peach ranged from

90.11 to 96.33 cm3. The highest fruit volume (96.33 cm

3) was recorded in peach

plants fertilized with 100 ppm of GA3. The lowest fruit volume (90.11 cm3) was

observed in control treatment.


The data for number of fruits showed that irrigation interval (I) and gibbrellic acid

(GA3) significantly influenced number of fruits kg-1

of peach while their interactive

effect was found non-significant (Table 4.2).

The highest number of fruit (9.58) kg-1

was observed in peach trees irrigated after

every 15th

day, while the minimum number of fruit (7.92) kg-1

was observed in peach

fruit plants irrigated after 10 days.

Increasing GA3 concentration from control to 150 ppm GA3 significantly reduced the

number of fruits kg-1

of peach. More number of fruits (9.67) kg-1

was observed in

control treatment. The lowest number of fruits (7.67) kg-1

was recorded in fruit plants

supplied with 150 ppm GA3, which was statistically at par with number of fruits (8.11)

kg-1

recorded in peach fruit trees fertilized with 100 ppm.

Fruit yield tree-1

(kg)

Fruit yield tree-1

of peach was significantly influenced by irrigation intervals (II) and

gibbrellic acid (GA3) concentrations whereas a non-significant variation was recorded

57

for their interaction (Table 4.2).

The highest fruit yield (74.50 kg) tree-1

was recorded in peach fruit trees irrigated

after every 5 days. The lowest fruit yield tree-1

(73.17 kg) was noted in peach fruit

trees irrigated after every 15th

day.

The mean data of Table 4.2 showed that fruit yield tree-1

of peach ranged from 70.94

to 74.56 kg. The highest fruit yield (74.56 kg) tree-1

was recorded in peach fruit trees

fertilized with 100 ppm of GA3, while control treatment (unfertilized peach trees with

GA3) gave the lowest fruit yield (70.94 kg) of peach.

Table 4. 2: Fruit weight (g), fruit volume (cm3), number of fruits kg

-1 and fruit

yield tree-1

(kg) of peach as affected by gibbrellic acid concentration

and irrigation intervals.

Irrigation

intervals

Parameters

Fruit

weight (g)

Fruit volume

(cm2)

No. of

fruits kg

-1

Fruit yield tree-1

(kg)

5 days 127.50 b 93.67 b 8.25 b 72.79 b

10 days 129.33 a 95.25 a 7.92 c 74.50 a

15 days 123.00 c 91.33 c 9.58 a 71.17 c

LSD (P ≤0.05) 1.05 0.73 0.23 1.38

Gibbrellic acid (ppm)

Control 123.39 c 90.11 d 9.67 a 70.94 d

50 127.61 b 94.67 b 8.89 b 73.67 b

100 129.61 a 96.33 a 8.11 c 74.56 a

150 125.83 b 92.56 c 7.77 c 72.11 c

LSD (P ≤0.05) 1.87 0.86 0.50 0.8

Interaction (IxG)

LSD (P≤ 0.05) Non Sig. Non Sig. Non Sig. Non Sig.


another

Non Sig. = Non-significant and *, ** = Significant at 5 and 1% level of probability.

58

Split pit incidence (%)

The mean data for split pits incidence in peach fruits are given in Table 4.3. The

analysis of variance showed that splits pits incidence was significantly affected by

irrigation intervals (II) and gibbrellic acid (GA3) concentration while the interactive

effect (II × GA3) was found non-significant.

The effect of irrigation intervals on split pit incidence showed that increasing the

interval of irrigation from 5 to 10 days significantly reduced the incidence of split pits

(20.86 to 7.46%) in peach fruits. While 15 days irrigation interval showed split pits

incidence of 7.96%.

The data for gibbrellic acid concentration showed that more split incidence (13.67%)

of peach fruits was recorded in control treatment. The lowest split pit incidence

(8.83%) was observed in peach fruit trees fertilized with GA3 at 150 ppm, which was

statistically similar with split incidence (9.67%) in peach fruit trees supplied with 100

ppm GA3.


)

Firmness of peach fruits was significantly affected by irrigation intervals (II) and

gibbrellic acid (GA3) concentration while their interaction was found non-significant

(Table 4.3).

Early (5 days) and late (15 days) irrigation interval had a negative effect on firmness

(5.21 and 4.97 kg cm-2

, respectively) of peach fruits. An optimum irrigation interval

of 10 days, significantly improved the fruit firmness (5.57 kg cm-2

) of peach.

The mean data of Table 4.3 clearly indicates that increasing gibbrellic acid levels from

control to 100 ppm GA3 significantly increased the firmness from 5.12 to 5.44 kg cm-2

.

A further increase in GA3 concentration of 150 ppm decreased the firmness (5.18 kg

cm-2

) of peach fruits.

59

Total soluble solids (0brix)

The data for total soluble solids (TSS) showed that irrigation interval (II) and

gibbrellic acid (GA3) significantly influenced total soluble solids of peach while their

interaction was found non-significant (Table 4.3).

The highest TSS (9.53 °brix) content was observed in peach trees irrigated after every

15th

day, while the minimum TSS (8.19 °brix) content of peach fruit was observed in

plants irrigated after 10 days.

The highest TSS (10.17 °brix) content was observed in fruits of untreated plants

(control treatment). The lowest TSS (8.05 °brix) content was noted in peach fruit

plants supplied with 100 ppm GA3 concentration.

Table 4. 3: Split pits incidence (%), fruit firmness (kg cm-2

) and total soluble

solids (°brix) of peach as affected by gibbrellic acid concentration and

irrigation intervals.

Irrigation intervals

Parameters

Split pits incidence

(%)

Firmness (kg

cm-2

)

Total soluble solids

(0brix)

5 days 20.86 a 5.21 b 9.19 b

10 days 7.46 b 5.57 a 8.19 c

15 days 7.96 b 4.97 c 9.53 a

LSD (P ≤0.05) 1.17 0.12 0.085

Gibbrellic acid (ppm)

Control 13.67 a 5.12 c 10.17 a

50 13.11 a 5.30 b 9.27 b

100 9.67 b 5.44 a 8.05 d

150 8.83 b 5.18 c 8.40 c

LSD (P ≤0.05) 1.19 0.11 0.31

Interaction (IxG)

LSD (P ≤0.05) Non Sig. Non Sig. Non Sig.


another

60

DISCUSSION

Leaf area (cm2)

The leaf area of peach increased by 19% at 10 days irrigation interval as compared

with too early (05 days) or late (15 days) irrigation management. In case of GA3

application, an increase of 5% was observed in leaf area of peach received 100 ppm

concentration as compared to untreated peach trees.

The vegetative growth is inhibited by water stress (Nyabundi and Hsiao, 1989) due to

decreased rates of transpiration and photosynthesis (Nuruddin et al., 2003). The

decrease in leaf area with 5 days irrigation might be due to retardation in leaf growth

(Table 1). The decrease in leaf growth might be attributed to the reduction in cell

elongation that led to the minimize cell tugor, cell volume and eventually the cell

growth. The reduction in cell growth is due to the blockage of xylem and phloem

vessels (Boyer, 1988) that was a barrier in translocation of the photo assimilates to the

targeted area hence affecting the leaf growth (Misra and Srivastava, 2000; Choi et al.,

2000 and Ayodele, 2001). Other reasons for decrease in leaf area due to over and

deficient irrigation is that imbalance of hormones arose from the increase in ABA and

decrease in auxin content. The antagonistic effect of ABA and auxin resulted in leaf

abscission (Sahid and Juraimi, 1998; Ayodele, 2001; Singh et al., 2006). Lovisolo and

Schuber (1998) also reported an inverse relationship between increasing and

decreasing the severity of water to the plants and concluded that both the stresses

reduce the leaf number as well as leaf area. Sahid and Juraima (1998) indicated that

water stress caused an inhibitory effect on the leaf area of treated plants (Nielson et al.,

1998; Kameli and Losel, 1996; Kawakami et al., 2006).

Besides the deficit irrigation, excess water also had a negative impact on the leaf

growth. The rate of photosynthesis is reduced in excess water due to the limited

supply of nitrogen (Adhikari, 1992; Gotame, 2006) which led to a decreased growth

rate. The reduced growth slows down the phloem transport of sugars, which is the

result of activity of triose phosphate for sucrose biosynthesis (Pezeshki, 2001; Sachs

61

and Vartapetian, 2007). The starch starts accumulating in the chloroplast (Wample and

Davies, 1983) leading to a negative effect on photosynthesis rate (Liao and Lin, 2001).

Moreover, leaf abscission increased in excess water due to the enhanced activity of

ethylene production (Adhikari, 1992) that results in premature leaf senescence

(Grassini et al., 2007), and the leaf area is negatively affected (Striker et al., 2005).

Fruit growth and yield related attributes

Fruit weight and fruit volume of peach irrigated at 10 days interval were increased by

1.44 and 1.69%, respectively. Further decrease was observed in both the attributes

with increased irrigation interval. Number of fruits kg-1

was decreased by 4% and

increased the fruit yield by 2.35% at 10 days irrigation interval as compared to other

irrigation treatments. Marsal et al. (2006) reported that tree water status is more

sensitive to irrigation restrictions. Three main mechanisms involved in determining

the negative effect of improper irrigation management on fruit growth and yield are

bud differentiation, carbon reservoir, and tree size (Naor et al., (1999).

Several changes in plant growth and developmental processes are often observed in

plants that are exposed to water stress overtime (Taiz and Zeiger, 1991). Nuruddin et

al. (2003) reported that deficit irrigation significantly reduced the photosynthesis and

transpiration. There is a negative effect of deficit irrigation on relative water content

of the soil and plant, thus plants lose their ability to restrict water loss though leaf

epidermis after stomata have attained minimum aperture (El-Jaafari, 2000).

The present results showed that number of fruits was significantly reduced in

excessive water stress (5 days). This decrease in number of fruits due to excessive

irrigation (5 days) might be due to the abscission of flower that decreased the number

of fruits (Abbott and Gough, 1987) and fruit yield (Bhatti et al., 2000). In contrast to

water deficit condition, the fruit size, number also decreased (Birhanu and Tilahun,

2010; Zotarelli et al., 2009) which resulted in lower yield (Table 4.2).

Under water deficit condition conditions the availability of free energy of water to the

62

plant is decreased. The production and accumulation of solutes (Glucose, Fructose,

Sucrose, Proline, Ascorbic Acid etc.) within the cell increased due to imbalance in

osmotic adjustment hence decreased the water potential (Nahar and Gretzmacher,

2002). Plant water status controls the physiological process and conditions, which

determine the quality and quantity of its growth disturbed by the unbalanced irrigation

management. All these factors results in severe reduction of fruit growth and yield

(Kramer, 1969).

In peach (Prunus persica (L.) Batsch), rapid initial fruit growth is followed by an

intermediate phase of slow growth. This is followed by a period of very rapid fresh

and dry weight increase that ends with maturity and ripening (Chalmers et al., 1983)

of fruit segments. At any stage improper moisture condition can lead to a decrease in

fruit growth and yield (Marsal et al., 2006).

The present results are in close conformity with Chalmers et al. (1981) and Li et al.

(1989), who reported a decrease in fruit size of peach under less moisture condition.

Turner (1980) also quoted similar results that deficit irrigation reduced the number

and diameter of the fruits and yield of tomato. Furthermore, a decrease in fruit number,

fruit size and total fruit yield of tomato were observed from plants subjected to

moisture stress (Birhanu and Tilahun, 2010; Zotarelli et al., 2009)

The foliar application of gibbrellic acid at 100 ppm increased the fruit weight, fruit

volume and yield to a maximum of 5.04%, 6.90% and 5.10%, respectively as

compared to control, while number of fruits kg-1

was decreased by 16.13%

respectively.

The increase in fruit weight, volume and yield might be due to the acceleration in cell

division and elongation due to application of GA3 (Usenik et al., 2005). Another

reason for the increase in fruit growth might be due to increase in plasticity of cell

wall by GA3 application, followed by hydrolysis of starch into sugar hence making

the water to enter to the cell causing elongation (Arteca, 1996). The application of

63

GA3 increased the phloem loading of carbohydrates from the source to the sink. This

in turned increased the size and weight of fruits (Kadir, 2004). These results are in

line with those obtained by Shahin et al. (2010) on "Anna" apple trees and Stino et al.

(2011) on "Le-Conte" pear trees. They found that yield was improved by foliar

application of GA3 in various concentrations. Furthermore, Pal et al. (1977) had

observed an increase in fruit diameter in Kinnow mandarin with GA3 (10 ppm) and

Kumar et al. (1996) also stated that gibberellic acid at 12.5 ppm resulted in the

highest fruit volume and weight in the fruit of strawberry. Kaur et al. (2008) also

reported that application of GA3 at 25 and 50 ppm increased the fruit weight in plum.

Bose et al. (1988) also recorded three times increase in fruit weight of mandarin.

Similar observation were recorded by Daulta and Beniwal (1983) in sweet orange

who obtained maximum fruit weight with the application of GA3 on sweet orange

fruits trees.

Fruit quality attributes

Irrigation at every 10th

day retained the maximum fruit firmness and TSS by 6.91 and

10.88%, respectively as compared to other irrigation treatments.

The decrease in fruit firmness and increase in TSS in deficit (15 Days) and excess

irrigation (05 Days) might be due to the fact that fruit firmness and TSS depends on

the structure of the cell wall (Pilling and Hofte, 2003). The cell separation from one

another due to the changes in cohesion of the pectin gel affects final texture and

quality of the fruit under excess or less water availability. Water stress reduced fruit

firmness which in turns increased the content of TSS in tomato (Birhanu and Tilahun,

2010). Another possible reason might be the changes in carbon partitioning in response

to unbalance irrigation that alters the distribution of carbon, increasing the allocation to

fruit hence resulted in a decrease in fruit firmness and increase in total soluble solids

(Fereres and Soriano, 2007).

Similar results have been reported by many authors in various species of citrus

64

(Ginestar and Castel, 1996; Monsalve-Gonzalez et al., 1993; Hutton et al. 2007, Velez

et al., 2007, Perez et al., 2008). They reported that negative effect of water stress was

observed on fruit quality (TSS, firmness, ascorbic acid and percent acidity). On the

other hand, Yakushiji et al. (1998) showed that water stress led to an increase in TSS

with a decrease in fruit firmness of mandarin. This might not be due dehydration of

the fruit, but rather a result of the osmoregulatory response caused by the lack of

water (Hockema and Etxeberria, 2001). The increase in TSS in excess water (5 days)

and deficit water (15 days) might be due to increase in solute concentrations thereby

increased accumulation of TSS in fruits (Nahar and Grezmacher, 2002; Nuruddin et

al., 2003). Plants under water stress adopts a strategy i.e. Osmoregulation (Ashraf,

2010), which is closely linked with regulation of plant water status by many ways like

osmotic adjustment, reduced transpiration through stomatal closure, root capability to

draw more water (Munn, 2011). All these factors made the plant to perform the

function of photosynthesis more efficiently resulted in more growth and yield of the

fruits (Munn, 2011). The TSS content of fruit plays an important and vital role in

osmotic adjustment under stress condition (Ullah et al., 1997).

In the present research, application of gibbrellic acid concentration (100 ppm)

increased the fruit firmness and decreased the TSS by 6.25 and 20.85%. This might be

due to the pre harvest application of GA3 reduced the polygalacuronases and pectin

methylestrase activities that resulted in increased fruit quality especially fruit firmness

(Andrews and Li, 1995).

The increment in fruit quality especially fruit firmness and fruit TSS might be due to

the role of gibbrellic acid in improving the growth of the fruit as GA3 enhanced the

translocation and mobilization of photo assimilates from the source (Singh et al.,

2003). Gibbrellic acid also caused an inhibitory effect on the above mentioned

enzymes causing the improvement in quality of the fruit (Andrews and Li, 1995). The

pre-harvest foliar application of GA3 enhanced the quality attributes in apple (Suzuki

et al., 1999). Furthermore, Kondo and Danjo (2001) suggested that GA3 treatment

65

delayed fruit ripening by blocking ABA activity.

Split pit incidence

Split pit incidence of peach was decreased by 64% at 10 days irrigation interval and

similarly 29.26 and 35.41% decrease was observed when treated with 100 and 150

ppm GA3 concentration respectively, statistically at par with each other.

The incidence of split pits in peach fruit reduced the market value, usually observed in

peach early cultivars (Patten et al., 1989). However, 40-70% splits pits observed in

early maturing cultivars of peach (Byrne et al., 1991). Certain factors like climatic

conditions, management practices (Larson et al., 1988), heavy thinning (Drogoudi et

al., 2009), are involved in spilt pit incidence. Among these practices would be

irrigation, fertilization and hormones, which results in the control of such disorders

(Engin et al., 2010). In recent years, the effect of excess or deficit water results in

splitting of pits as well as doubling had also been investigated. Water stress (excess

and deficit) during the summer months (Patten et al. 1989; Larson et al., 1988;

Johnson et al., 1992; Kader, 2002) were reported to increase the development of split

pits. The effects of water stress during the final stage of rapid fruit growth were also

shown to be more decisive in terms of decreasing fruit size and increasing split pits in

peach (Chalmers and Van den Ende 1975; Li et al., 1989; Crisosto et al., 1994; Bussi

et al., 1999; Besset et al., 2001). So optimum irrigation interval reduced the split pits

incidence of peach. The early ripening cultivars are more susceptible to such disorders

as the pit hardening and final swell phases of fruit development occur relatively close

together in time (Barcelon et al. 1999). In fruits with shattered pits, the pits are broken

in several places and the pit cavity may contain a gummy substance. Hsiao (1973)

suggested that water stress acted on changing the balance between hormones and

nutrients in a plant in a way that indirectly induced this disorder. Gibberellic acid

(GA3) is known to inhibit flower bud differentiation in deciduous fruits (Hull and

Lewis, 1959; Bradley and Crane 1960). Gibberellin sprays applied during the flower

bud differentiation period reduced the following season’s flowering and increased

66

fruit size and reduces physiological disorders in peach (Taylor and Taylor 1998).

Adequate irrigation complemented with gibberellins had a pronounced effect of

split/shattered pits in peach ameliorated such effect (Engin et al., 2010).

67


Summary

The experiment entitled “Influence of irrigation intervals and gibbrellic acid (GA3) on

split pits incidence and fruit quality of peach” was carried out at Horticulture

Research Farm, The University of Agriculture Peshawar with the objectives to

standardize the irrigation management and optimize the gibbrellic acid concentration

for improving quality and reducing split pits incidence in peach Cv. Early Grand

during the year, 2015.

During the year 2014, peach trees were thinned at various intensities (20, 40 and 60%)

at 7, 14 and 21 days after fruit set. Results of the previous year showed that heavy and

early thinning i.e. 40 and 60% resulted in split pit incidence in peach fruits. So to

overcome this problem another sequential experiment was planned during 2015.

Optimized fruit thinning intensity i.e. 40% and thinning time i.e. 14 days after fruit set

was kept constant in all fruit trees and irrigated at various intervals with foliar

application of GA3 in various concentrations. This experiment was carried out by

using Ramdomized Complete Block Design (RCBD) with split plot arrangement

replicated three times.

Various growth and yield attributes were studied i.e. leaf area (cm2), fruit weight (g),

fruit volume (cm3), number of fruit kg

-1, fruit yield tree

-1 (kg), split pit incidence (%),

fruit firmness (kg cm-2

) and total soluble (°brix) during the course of the experiment.

The experimental results for all the attributes are given as under.

Concerning the effect of irrigation intervals, the highest leaf area (27.40 cm2), fruit

weight (129.33 g), fruit volume (95.25 cm3), fruit yield (74.50 kg) tree

-1, fruit

firmness (5.57 kg cm-2

), less number of fruits (7.92), split pit incidence (7.46%) and

TSS (8.19 °brix) were recorded in fruit trees irrigated after every 10 days. The lowest

data for all these attributes were noted in fruit plants irrigated after 15 days. The

lowest leaf area (23.00 cm2) was recorded in fruits irrigated after every 5 days interval.

Whereas, fruit trees irrigated after 15 days interval showed the lowest fruit weight

68

(123.00 g), fruit volume (91.33 cm3), fruit yield (73.17 kg) tree

-1, fruit firmness (4.97

kg cm-2

), highest number of fruits (9.58), TSS (9.53 °brix) and highest split pits

incidence (20.86%) were recorded in fruits trees irrigated after 5 days.

The experimental results also showed that alone application of gibbrellic acid had a

significant effect on all the attributes except leaf area. However, more fruit weight

(129.61 g), fruit volume (93.33 cm3), fruit yield (74.56 kg), fruit firmness (5.44 kg

cm-2

) and less total soluble solids (8.05 °brix) were recorded when fruits were sprayed

with 100 ppm GA3, while the lowest split pits incidences (8.83%) and number of

fruits (7.11) were noted in fruits trees treated with 150 ppm GA3 solution. The effect

of GA3 on leaf area was found non-significant. The lowest fruit weight (123.39 g),

fruit volume (90.11 cm3), fruit yield (70.94 kg), fruit firmness (5.12 kg cm

-2), more

number of fruits (9.67), split pits incidences (13.67%) and total soluble solids

(10.17 °brix) were recorded in fruits of control treatment. A non-significant variation

was recoded for all the studied attributes in term of interactive effect of irrigation

intervals and foliar application of GA3.

Conclusions

The following conclusions are made from the present experiment.

Irrigation interval of 10 days to peach trees significantly increased fruit weight,

fruit volume, fruit yield and reduced the number of fruit kg-1

and split pit

incidence

The foliar application of gibbrellic acid (GA3) at 100 ppm (berry sized stage)

significantly increased fruit weight, fruit volume and fruit yield of peach

Furthermore, the foliar application of GA3 at 150 ppm significantly reduced

the split pit incidence in peach fruits which was at par with results of fruit

received GA3 at 100 ppm

The interactive effect of GA3 and irrigation on all the studied attributes was

found non-significant

69

Recommendations

Based on the conclusions the following recommendations are made

Peach trees should be irrigated after every 10th

day to minimize the split pit

incidence without affecting the fruit growth and yield

The foliar application of gibbrellic acid (GA3 at 100 ppm) at berry sized fruit

stage, could be used to improve fruit yield and reduce the split pit incidence of

peach fruits cv Early Grand

70

CHAPTER V

EFFECT OF CALCIUM SOURCES AND CONCENTRATIONS ON

THE QUALITY AND STORAGE PERFORMANCE OF PEACH




ABSTRACT

The present study was undertaken to study the effect of calcium sources and

concentration on the quality and storage performance of peach. The field experiment

was laid out in Randomized Complete Block Design (RCBD) with two factors

replicated three times. Peach fruit trees were sprayed with three sources of calcium

(Calcium chloride, Calcium nitrate and Calcium sulphate) at three concentrations (0.5,

0.75 and 1.0%). The harvested fruits were shifted to Post harvest lab, Hort. Deptt. The

University of Agriculture Peshawar, during the year 2014.The fruits of all the

treatments was stored for 30 days at 10 days interval. The experimental results

showed that calcium sources, concentration and storage duration significantly affected

all the studied attributes. However, more fruit firmness (5.57 and 5.69 kg cm2), high

fruit calcium content (9.38 and 9.11%), less TSS (8.57 and 8.26 °brix), TSS-acid ratio

(12.62 and 11.48), brown rot incidence (4.83 and 4.15%), weight loss (4.81 and

4.76%), ion leakage from cell membrane (37.19 and 37.28%) and cell wall (20.33 and

20.92%) were recorded by the alone application of calcium chloride at 1.0% calcium

concentration, respectively. The effect of calcium sources and concentration on the

rest of the quality attributes were found non-significant. The means for storage

duration showed that freshly harvested fruits resulted in better fruit firmness (5.69 kg

cm2), TSS (8.67 °brix), ascorbic acid content (6.43 mg 100 g

-1), ion leakage from cell

membrane and cell wall (41.56 and 20.08%, respectively) while more TSS-acid ratio

(0.74), less brown rot incidence (10.61%) and weight loss (6.12%) were noted in

fruits stored for 10 days. The effect of storage on fruit calcium content was found

non-significant. The interaction of Ca-source and Ca-concentration for most of the

studied attributes were found significant, while rest of the interactions had a

non-significant variation for the studied attributes. It is concluded from the present

results that pre-harvest foliar application of CaCl2 (1.0%) at berry size fruit stage

significantly retained the quality attributes for 30 days during storage with an average

temperature 8±2 and relative humidity 50%, hence recommended for the grower of

Khyber Pakhtunkhwa.

71

INTRODUCTION

Postharvest losses of horticultural produce may occur from harvesting to packing,

storing, shipments, marketing and final delivery to the consumers (Inaba and Crandall,

1986). Main reasons in post-harvest deterioration of fruits and vegetables are

pre-harvest cultural measurements like improper selection of rootstocks and scions,

un-improved production practices, non judicious use of fertilizer, pests and diseases

management, lack of skill for harvesting of crop at proper stage and postharvest

storage problems such as non removal of field heat, negligence regarding

management of hygienic problems, improper promotional materials (packaging) and

grading of fruits, poor transport conditions, storage and marketing approaches (Kader,

2002).

Less attention has been paid to the production of peach fruit crop, mainly because of

its perishability and short postharvest life during storage (Khan et al., 2016). The

post-harvest losses in peach are about 23% (Khan, 2012). Pre-harvest calcium sprays

are one of the most important practices of the new strategies applied in the Integrated

Fruit Production systems, improving fruit characteristics and minimizing fungicide

sprays towards the end of the harvest period and improve fruit resistance to brown rot

(Conway et al., 1987). Sprays with calcium chloride based formulas are extensively

used, whereas chelated calcium sources are promoted as alternative sources,

characterized by a high absorption capacity (Lester and Grusak, 2004). Calcium, as a

constituent of the cell wall, plays an important role in forming cross-bridges which

influence cell wall strength and regarded as the last barrier before cell separation (Fry,

2004). Exogenously applied Ca stabilizes the plant cell wall and protects it from cell

wall degrading enzymes (White and Broadley, 2003).

Calcium sprays during fruit development provide a safe mode of supplementing

endogenous calcium in a range of fresh fruits (Tzoutzoukoua and Bouranis, 1997;

Raese and Drake, 2000 a, b), although the process of calcium diffusion into fruits is

not well defined and contradictory results have been found regarding the effect of

72

exogenous application of calcium in improving calcium content in peach fruits

(Crisosto et al., 2000; Serrano et al., 2004). The lenticels seem to have a significant

positive effect on calcium penetration. Additionally, cracks and surface discontinuities,

which are more apparent during the late phase of fruit growth, seem to offer sites for

calcium penetration (Glenn et al., 1985).

Keeping in view the perishability of peach fruits and the role of calcium in enhancing

and retaining the shelf life for a longer period of time, the present experiment was

designed with the following objectives.

To study the influence of various sources of calcium as pre-harvest foliar spray

on quality fruit production of peach cv. Early Grand during storage

To optimize the appropriate concentration of calcium to retain the

physico-chemical attributes of peach fruits during storage

To study the interactive effect of calcium sources, concentration and storage

duration for better shelf life of peach fruit during storage

73


The experiment was carried out at Horticultural Research Farm and Postharvest

Horticulture Laboratory, The University of Agriculture Peshawar during the year

2014-15, with the objective to optimize the best calcium source and its concentration

to retain the physico-chemical attributes of peach fruits during storage of peach fruit

cv. Early Grand.

The experiment was carried out in two phases. During the first phase, peach fruits

sprayed with different sources of calcium at various concentrations at plateau stage.

The field experiment was conducted by using RCB Design with two factors replicated

three times. One control was kept both for calcium sources and concentration. For this

purpose, three uniform sized trees were taken randomly for each treatment. During the

second phase, the harvested fruits were brought to Post harvest laboratory,

Horticulture Department and arranged in three factorial arrangements in Randomized

Complete Block Design (RCBD) to study the effect of calcium sources and their

concentrations on physic-chemical performance of peach fruit at low temperature

(8+2 at 50% RH). The details of the factors are given as under.

Factors

Control (for Ca sources and concentration)

Factor A: Calcium Sources: Calcium chloride (CaCl2), Calcium nitrate (Ca(NO3)2),

and Calcium sulphate (CaSO4)

Factor B: Calcium concentrations: 0.5%, 0.75% and 1.0%

Factor C: Storage duration: 0 days (Fresh harvest), 10 days, 20 days and 30 days

Preparation of Calcium Solution

Three calcium sources i-e calcium chloride, calcium nitrate and calcium sulphate of

Sigma and Ridyal Company were used during the course of experiment. The percent

calcium solutions of the respective sources were prepared first by calculating calcium

in molecular formula. Take 1.84, 2.04 and 2.72g of CaCl2 for preparing 0.5, 0.75 and

1% (g/100 ml) solutions. Follow similar procedure for prepareing percent solution for

74

rest of calcium sources. The detail of each source along with their concentrations is

given as under.

Attributes studied

The data was collected with the following parameters

The procedure for determining fruits firmness (kg cm-2

), TSS, TA, TSS-Acid ratio and

Ascorbic acid is already given in Chapter 3 (Experiment 1)

Percent reducing and non reducing sugars

Non-reducing sugars were determined by Lane and Eynon method, as reported in

Iqtidar and Saleemullah (2004).

Brown rot incidence (%)

Brown rot incidence (%) in each replication and treatment was physically checked on

regular basis. Brown rot was confirmed by the Department of Plant Pathology, The

University of Agriculture Peshawar. Percent Brown rot incidence was calculated with

the following formula.

Sources of

calcium

Chemical

Formula

Molecular

weight(g)

Calculations

of Chemical

for 0.5%

solution

Calculations

of Chemical

for 0.5%

solution

Calculations

of Chemical

for 0.5%

solution

Calcium

Chloride

CaCl2.2H2O 147.02 1.84 2.04 2.72

Calcium

Nitrate

Ca (NO3)2 164 1.21 1.82 2.43

Calcium

Sulphate

CaSO4.2H2O 172.17 0.116 1.74 2.32

75

Weight loss (%)

Six freshly harvested fruits were kept separetly for examining the weight loss of

peach fruits. Data was taken on regular basis at 0, 10, 20 and 30 days from each

treatment and in each replication. The loss in weight was measured using the formula

given below.

Calcium content of fruits (%)

For calculating fruit calcium content, the procedure as described by Adrian and

Stevens (1977) was followed. Uniform sized fruits were cut and washed with distall

water, followed by weighing and drying in oven at 70 °C. Cleaning of sample by

brush and acetone is followed after grinding it with Tema Mill which was dryashed

thereafter. The sample was mixed with concentrated HNO3 (10 ml) for carring

digestion and kept them mixture overnight. After heating the sample on hot plate (til

fumes production of red NO2), is cooled and mized with 70% HClO4 (2-4 ml) until a

small volume is left over. After placing the sample in a 50 ml flask, dilution with

distall water is done and Atomic Absorption Spectrophotometer (Model GBC AA 932)

was run for determination of calcium content in the sample. Before running

instructions of manufacturer for calibrating Spectorphotometer (using standard

solution of 5 µg-ml-1

) should be strickly followed.

Electrolyte leakage (%)

Electrolyte leakage (EC) helps to find out the Cell wall and membrane stability and

permeability. For finding EC of fruit sample of peach, 10 mm flesh disc was removed

using a stainless stell core borer. Cytosol liquid and juice of the fruit was removed

before washing the discs for 1 min. A stand was fixed and three discs were poured

with 20 ml of distall water and shaked on rotator for 30 minutes. The 1st EC was

76

recoreded after 30 minutes using EC meter and then 2nd

EC was taken after 60

minutes. The total conductivity was recorded by giving three freeze and thaw cycles

cell wall and membrane ion leakage (%) was recorded from EC readings using the

formulas respectively;


The data recorded were arranged according to Randomized Complete Block Design

and was subjected to Analysis of Variance technique as given by Jan et al. (2009). It

was then analyzed using statistical software Statistix 8.1 (Statistix_8 Analytical

Software. 2003). If the data was found significant, LSD test was used for comparing

the means.

77

RESULTS

Fruit Firmness (kg cm-2

)

Calcium sources (CaS), calcium concentrations (CaC) and storage days (SD) had a

significant effect on firmness of peach fruits. The effect of all the interactions was

found non-significant except CaS×CaC and CaC ×SD (Table 5.1).

The data for Ca-sources showed that firmer fruits (5.57 kg cm-2

) were obtained from

peach plants supplied with Calcium chloride (CaCl2). The lowest firmness (5.24

kg.cm-2

) was noted in fruits of peach trees, fertilized with calcium nitrate [Ca(NO3)4]

Increasing calcium concentrations from 0 to 1% showed an increase in firmennss of

peach fruits from 5.04 to 5.69 kg.cm-2

.

Maximum firmness (5.69 kg.cm2) of peach fruits was recorded in at 0 day storage,

followed by firmness (5.30 kg.cm2) of peach fruits stored for 10 days. Fruits of 30

th

day storage showed the lowest fruit firmness (4.78 kg.cm2).

Regarding CaS×CaC interaction, more firmer (5.86 kg cm2) peach fruits were

observed in peach trees fertilized with 1% CaCl2 solution. Fruits treated with 0.5%

Ca(NO3)2 solution gave the lowest firmness (4.86 kg cm2) of peach fruits (Fig 5.1).

The interaction of CaC×SD was also found significant. The data showed that highest

fruit firmness (6.08 kg cm2) was observed in freshly harvested peach fruits sprayed

with 1% Ca solution. The lowest fruit firmness (4.99 kg cm2) was recorded in fruits

treated with 0.5% Ca solution stored for 30 days (Fig 5.2).

Total Soluble Solids (°brix)

Calcium sources (CaS), concentration (CaC), storage duration (SD), CaS×CaC

interaction significantly influenced the TSS of peach fruits whereas a non significant

response was observed for all the interactions (Table 5.1).

The data for Ca-sources showed that the highest TSS (9.37 °brix) content of peach

fruits were observed when peach trees treated with Ca(NO3)2, followed by Ca(SO4)2

where TSS was recorded as 9.08 °brix. While, peach fruits trees treated with CaCl2

source of calcium recorded the lowest TSS (8.57 °brix) content in peach fruits.

78

Concerning the means for the application of various concentrations of calcium, its

levels significantly retained the TSS of peach fruits during storage. The peach plants

sprayed with 0.5, 0.75 and 1% Ca solution produced fruit with TSS contents of 9.44,

9.30 and 8.26 °brix respectively. Fruits of control treatment showed a TSS content of

9.42 °brix.

The highest TSS (9.99 °brix) content was recorded in peach fruits at 30 days storage,

followed by TSS (9.28 °brix) content in peach fruits at 20 day storage. The lowest

TSS (8.67 °brix) was recorded in fruits of control treatment.

Total soluble solids were significantly decreased at each level of calcium in all the

calcium sources. However, the highest TSS (9.72 °brix) was recorded in peach fruits

treated with 0.5% Ca(NO3)2 solution, while 0.5% Ca(NO3)2 solution gave minimum

TSS (7.33 °brix) of peach fruits (Fig 5.3).

Percent acidity (%)

Percent acidity (TA) was non-significantly affected by Ca-sources, concentration and

all the two and three way interactions except storage duration (Table 5.1).

The highest percent acidity (0.76%) of peach fruits was recorded in freshly harvested

fruits, which was statistically at par with percent acidity (0.73%) in peach fruits stored

for 10 days. The lowest percent acidity (0.64%) of peach fruits was noted in fruits

kept for 30 days after harvest.

TSS-acid ratio

Calcium sources (CaS), concentration (CaC), storage duration (SD) significantly

influenced TSS-acid ratio of peach fruits, while all the two and three way interactions

were found non-significant (Table 5.1).

The data for calcium sources showed that CaCl2 proved to be the best Ca-source in

terms of retaining TSS-acid ratio (12.62) of peach fruits. The peach fruits sprayed

with Ca(NO3)2 and Ca(SO4)3 as source of calcium didn’t retain the TSS-acid ratio

(13.79 and 13.01), respectively during storage.

79

Concerning the means for Ca-concentrations, increasing calcium levels from 0.5 to

1.0% significantly decreased the TSS-acid ratio from 14.27 to 11.48. However, fruit

trees left untreated recorded a TSS-acid ratio of 13.51.

The means for storage duration showed that more TSS-acid ratio (15.08) was found in

peach fruits kept for 30 days. The lowest TSS-acid ratio (11.92) was found in peach

fruits of 10 day storage.

80

Table 5. 1: Firmness (kg.cm-2

), TSS (°brix), percent acidity (%) and TSS-acid

ratio of peach as affected by calcium sources and concentration

during storage

Calcium Sources

(CaS)

Parameters

Fruit firmness

(kg cm-2

)

Total soluble

solids (0Brix)

Percent

acidity (%)

TSS-acid ratio

CaCl2 5.57 a 8.57 c 0.74 12.62 b

Ca(NO3)2 5.24 b 9.37 a 0.72 13.79 a

Ca(SO4)2 5.35 b 9.08 b 0.73 13.01 a

LSD (P≤0.05) 0.16 0.272 Non Sig. 0.922

Ca. Concentrations (CaC)

Control 5.04 b 9.42 a 0.69 13.51 a

0.5 5.20 b 9.44 a 0.73 14.27 a

0.75 5.27 b 9.30 a 0.72 13.67 a

1.0 5.69 a 8.26 b 0.73 11.48 b

LSD (P≤0.05) 0.16 0.272 Non Sig. 0.922

Storage duration (SD)

0 5.69 a 8.67 d 0.76 a 11.94 c

10 5.30 b 8.90 c 0.73 ab 11.92 c

20 5.09 c 9.28 b 0.70 b 13.46 b

30 4.78 d 9.99 a 0.64 c 15.98 a

LSD (P≤0.05) 0.18 0.314 0.035 1.064

Interactions (LSD at P≤0.05)

CaSxCaC Fig. 5.1 Fig. 5.3 -- --

Significance * *** Non Sig. Non Sig.

CaSxSt -- -- -- --

Significance Non Sig. Non Sig. Non Sig. Non Sig.

CaCxSD Fig 5.2 -- -- --

Significance *** Non Sig. Non Sig. Non Sig.

CaSxCaCxSD -- -- -- --

Significance Non Sig. Non Sig. Non Sig. Non Sig.

Means, followed by same letter(s) in column, do not differ, significantly from one

another

Non Sig. = Non-significant and *, ** = Significant at P≤0.05 and P≤0.01,

respectively.

81

Ca. Concentration (%)

0.5 0.75 1.0

Fru

it fir

mne

ss (

kg c

m-2

)

4.6

4.8

5.0

5.2

5.4

5.6

5.8

6.0

CaCl2

Ca(NO3)2

Ca(SO4)2

Fig 5.1 Interactive effect of Ca. sources and concentrations on fruit firmness

(kg.cm-2

) of peach

Calcium concentration (%)

0.5 0.75 1.0

Fru

it fir

mne

ss (

kg

cm

-2)

4.8

5.0

5.2

5.4

5.6

5.8

6.0

6.2

6.4

0

10

20

30

Fig 5. 2: Interactive effect of Ca. concentrations and storage duration on fruit

firmness (kg.cm-2

) of peach

82


0.5 0.75 1.0

To

tal s

olu

ble

so

lids (

0b

rix)

7.0

7.5

8.0

8.5

9.0

9.5

10.0

CaCl2

Ca(NO3)2

Ca(SO4)2

Fig 5.3: Interactive effect of Ca. sources and concentrations on total soluble

solids (°brix) of peach

83

Ascorbic acid (mg.100g-1

)

Ascorbic acid of peach fruits was non-significantly affected by the Ca. sources, their

concentrations, the two way and three way interactions except storage days (Table

5.2).

More vitamin C content (6.42 mg.100g-1

) of peach fruits was found in control

treatment. On other side, peach fruit stored for 30 days had the lowest ascorbic acid

(5.94 mg 100g-1

) content during storage.

Reducing sugars (%)

The effect of Ca. concentrations, various Ca. sources and their interactions on

reducing sugars of peach fruits was found non significant. Storage days showed its

effect on reducing sugars of peach fruits (Table 5.2)

The reducing sugars of peach fruit during storage increased with increasing the

storage durations. However, the highest reducing sugars (2.23%) were recorded in

peach fruits stored for 30 days, followed by reducing sugars (1.99%) in peach fruits

stored after 20 days. The lowest reducing sugars (1.38%) were recorded in freshly

harvest peach fruits (control treatment).

Non reducing sugars

Storage duration significantly influenced non reducing sugars of peach fruits while

the effect of Ca-sources, its different concentrations and all the interactions for

non-reducing sugars of peach fruits were found non-significant (Table 5.2)

A significant variation was recorded for non-reducing sugars during storage. The

highest non reducing sugars (4.40%) were recorded in peach fruits harvested as fresh,

followed by non reducing sugars (4.20%) in peach fruits stored for 10 days. The

lowest non reducing sugars (4.02%) of peach fruits were recorded in fruits stored for

30 days of storage.

84

Table 5. 2: Ascorbic acid (mg 100g-1

), reducing sugars (%) and non reducing

sugars (%) of peach as affected by calcium sources and concentration

during storage

Calcium Sources

(CaS)

Parameters

Ascorbic acid

(mg 100g-1

)

Reducing sugars

(%)

Non reducing sugars

(%)

CaCl2 6.38 1.84 4.22

Ca(NO3)2 6.38 1.81 4.19

Ca(SO4)2 6.34 1.79 4.21

LSD (P≤0.05) Non Sig. Non Sig. Non Sig.


Control 6.18 1.85 4.17

0.5 6.32 1.76 4.19

0.75 6.38 1.78 4.20

1.0 6.40 1.91 4.22

LSD (P≤0.05) Non Sig. Non Sig. Non Sig.


0 6.42 a 1.38 d 4.40 a

10 6.40 a 1.73 c 4.20 b

20 6.33 a 1.99 b 4.15 b

30 5.94 b 2.23 a 4.02 c

LSD (P≤0.05) 0.214 0.237 0.082

Significance


CaSxCaC -- -- --

Significance Non Sig. Non Sig. Non Sig.

CaSxSt -- -- --


CaCxSD -- -- --


CaSxCaCxSD -- -- --



another


respectively.

85

Brown rot incidence (%)

A significant variation was observed brown rot incidence by the application of various

Ca. sources, their concentration, storage day and Ca. sources × Ca. concentrations

while all the other interactions were found non significant (Table 5.3).

The data for calcium sources showed that the fruit sprayed with Ca(NO3)2 as a source

of calcium showed that the highest brown rot incidence (19.23%), closely followed by

brown rot incidence (17.38%) in peach fruits of plants sprayed with Ca(SO4)2, used as

source of calcium. The lowest brown rot incidence (14.86%) was recorded in fruits of

peach plants treated with CaCl2 during 30 days of storage.

Concerning the means for Ca-concentrations, the maximum brown rot incidence

(21.21%) was recorded in fruits of control treatment, which were statistically similar

with brown rot incidence (19.59 and 17.72%) in peach fruits sprayed with 0.5 and

0.75% Ca solution, respectively. The lowest brown rot incidence (14.15) was noted in

fruits of peach trees fertilized with 1.0% Ca solution.

The highest brown rot incidence (23.94%) was noted in peach fruits kept in storage

for 30 days, which was at par with brown rot incidence (22.18%) in peach fruits

stored for 20 days. The lowest brown rot incidence (20.61%) was observed in peach

fruits stored for 10 days after harvest.

The CaS×CaC interaction was also found significant. The highest brown rot incidence

(24.67%) was taken from fruits of peach trees sprayed with Ca(NO3)2 at 0.5%. The

lowest brown rot incidence (15.23%) was observed in fruits of peach plants treated

with CaCl2 at 1% (Fig 5.4).

Weight loss (%)

The data for weight loss showed that calcium sources (CaS), its concentrations (CaC),

storage durations (SD) and CaS×CaC interaction had a significant effect on weight

loss of peach fruits. The rest of the interactions were found non-significant (Table

5.3).

The data for Ca-sources showed that fruits of peach plants treated with CaCl2

significantly retained the percent weight loss (14.81%) as compared to weight loss

86

(17.51 and 18.31%) respectively, recorded in fruits obtained from the plants treated

with Ca(SO4)2 and Ca(NO3)4 as Ca-source.

The maximum weight loss (18.07%) was recorded in fruits of peach plants sprayed

with Ca at 0.5%, which was statistically at par with weight loss (17.80%) in peach

fruit trees sprayed with 0.75% Ca solution. The minimum percent weight loss

(14.76%) was recorded in fruits of peach trees sprayed with 1.0% Ca. The fruits of

peach trees in control treatment showed weight loss of 18.05%.

The means for storage duration showed that percent weight loss significantly

increased with increase in storage duration. The highest percent weight loss (23.80%)

was recorded in peach fruits kept for 30 days in storage. The lowest weight loss

(16.12%) was recorded in fruits stored for 10 days.

A significant variation was observed between the Ca-source and concentration

interaction. The highest percent weight loss (21.71%) was observed in fruits of peach

plants sprayed with 0.5% Ca(NO3)2 solution. The lowest percent weight loss (13.57%)

was recorded in fruits of peach plants treated with 1% CaCl2 solution.

Fruit calcium content (%)

The analysis of variance of the data showed that Ca-sources, Ca-concentrations and

the interaction between Ca-sources and its concentrations had a significant effect on

calcium content of peach fruit, while storage durations and the rest of the interaction

had a non significant effect on calcium content of peach fruits (Table 5.3).

The data for Ca-sources showed that the highest fruit calcium content (9.38%) was

observed in fruits of peach plants treated with CaCl2, followed by fruit calcium

content (8.94%) noted in fruits of plants sprayed with Ca(SO4)2 as Ca-source. The

lowest fruit calcium content (7.53%) was recorded in fruit of plant received Ca(NO3)2

as Ca-source.

Concerning the means for calcium concentrations, the highest fruit calcium content

(8.94%) was recorded in in peach fruits of plants treated with 1% Ca solution. The

lowest fruit calcium content (7.98) was recorded in untreated fruits of peach plants.

All the two way and three way interactions were found non-significant except

87

CaS×CaC interaction. The mean data table showed that fruit calcium content was

significantly increased at each level of calcium in all the sources. However, the

highest calcium content (9.87%) was recorded in fruits of plants treated with 1%

CaCl2 solution while, the lowest fruit calcium content (6.90%) was observed in plants

sprayed with 0.5% Ca(NO3)2 solution.

Cell wall ion leakage (%)

Calcium concentrations, sources and storage days had a significant effect on cell wall

ion leakage of peach fruits while all the interactions were found non-significant for

cell wall ion leakage (Table 5.3).

The data for calcium sources showed that fruits of peach trees treated with Ca(NO3)2

source of calcium had the highest ion leakage from cell wall (24.50%), closely

followed by cell wall ion leakage (23.76%) in fruits of peach trees sprayed with

Ca(SO4)2. The lowest cell wall ion leakage (20.33%) was recorded in fruits of peach

plants treated with CaCl2.

Concerning the means for Ca-concentration, maximum ion leakage from cell wall

(25.08%) was recorded in fruits of peach plants in control treatment. The lowest ion

leakage from cell wall (20.92%) was observed in fruits of peach plants supplied with

1.0% Ca solution.

The highest cell wall ion leakage (27.44%) was observed in peach fruits kept in

storage for 30 days. The lowest cell wall ion leakage (20.08%) was found in freshly

harvested peaches.

Cell membrane ion leakage (%)

Cell membrane ion leakage was significantly influenced by Ca-sources, its various

concentrations, storage durations while all the two and three way interactions were

found non-significant (Table 5.3)

The data for calcium sources showed that fruit of plants treated with Ca(NO3)2 as

Ca-source showed the highest ion leakage (44.25%) from cell membrane during

storage, followed by cell membrane ion leakage (40.83%) in fruits of peach plants

sprayed with Ca(SO4)2. The lowest cell membrane ion leakage (37.19%) was recorded

88

in fruits of peach plants treated with CaCl2 as source of calcium.

Means across the Ca-concentrations, the maximum ion leakage (49.08%) from cell

membrane of peach fruits was recorded in control treatment. The lowest ion leakage

(37.28%) from cell membrane was observed in fruits of peach plants supplied with

1.0% Ca solution.

Ion leakage from cell membrane had also showed a significant response to storage

durations. The highest cell membrane ion leakage (48.46%) was noted in peach fruits

kept in storage for 30 days. The lowest ion leakage (41.56%) from cell membrane was

recorded in freshly harvested fruits, which was statistically at par with cell membrane

ion leakage (44.67%) in fruits stored for 10 days.

89

Table 5. 3:Brown rot incidence (%), Fruit calcium content (%), Cell wall and cell

membrane ion leakage (%) of peach as affected by calcium sources

and concentration during storage

Calcium Sources

(CaS)

Parameters

Brown rot

incidence (%)

Weight

loss (%)

Fruit Calcium

content (%)

Cell wall Ion

leakage (%)

Cell membrane

Ion leakage

(%)

CaCl2 14.86 b 14.81 b 9.38 a 20.33 b 37.19 c

Ca(NO3)2 19.23 a 18.31 a 7.53 c 24.50 a 44.25 a

Ca(SO4)2 17.38 a 17.51 a 8.94 b 23.76 a 40.83 b

LSD (P≤0.05) 2.522 2.632 0.12 1.622 2.853


Control 21.21 a 18.05 a 7.98 d 25.08 a 49.08 a

0.5 19.59 a 18.07 a 8.14 c 24.93 a 44.42 b

0.75 17.72 a 17.80 a 8.76 b 22.75 b 40.58 c

1.0 14.15 b 14.76 b 8.94 a 20.92 c 37.28 d

LSD (P≤0.05) 2.522 2.632 0.12 1.622 2.853


0 0.00 c 0.00 d 8.41 20.08 c 41.55 a

10 10.61 b 16.12 c 8.40 23.20 b 44.66 ab

20 12.18 ab 19.94 b 8.38 25.16 b 45.00 b

30 13.94 a 23.80 a 8.32 27.44 a 48.46 c

LSD (P≤0.05) 2.912 3.039 Ns 1.873 3.294

Significance * Ns *** * ***


CaSxCaC Fig. 5.4 Fig. 5.5 Fig. 5.6

Significance * * *** Non Sig. Non Sig.

CaSxSt

Significance Non Sig. Non Sig. Non Sig. Non Sig. Non Sig.

CaCxSD


CaSxCaCxSD



another


respectively.

90


0.5 0.75 1.0

Bro

wn r

ot in

cid

ence (

%)

12

14

16

18

20

22

24

26

28

CaCl2

Ca(NO3)2

Ca(SO4)2

Fig 5.4: Interactive effect of Ca. sources and concentrations on Brown rot

incidence (%) of peach


0.5 0.75 1.0

Weig

ht lo

ss (

%)

12

14

16

18

20

22

24

CaCl2

Ca(NO3)2

Ca(SO4)2

Fig 5. 5: Interactive effect of Ca. sources and concentrations on weight loss (%)

of peach

91


0.5 0.75 1.0

Fru

it c

alc

ium

conte

nt (%

)

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

CaCl2

Ca(NO3)2

Ca(SO4)2

Fig 5.6: Interactive effect of Ca. sources and concentrations on fruit calcium

content (%) of peach

92

DISCUSSION

Quality attributes of peach fruits

The present results showed that the fruit of peach tree sprayed with 1% calcium

concentration (highest calcium concentration) increased the fruit firmness by 12.90%

as compared to other control and other calcium concentration. As concerned Ca

sources, fruit firmness increased by 10.52% in fruits of peach trees treated with

calcium chloride as compared to control and other calcium treatments.

Application of Ca improves post-harvest life of fruits and vegetables (Rees, 1975) by

retaining firmness and other related quality attributes. Calcium strengthens the cell

wall by binding the free carboxyl group of polygalactruonate polymers (Rees, 1975),

resisting the fruit against the hydrolytic enzyme activity (Wills and Rigney, 1979;

Buescher and Hobson, 1982). Calcium sources retained fruit firmness in peach as

compared to untreated fruits (Manganaris et al., 2005) which greatly confirms the

present results. Similarly the golden delicious apples treated with calcium chloride (2

and 4%) significantly retained the fruit firmness of apple for 6 months compared to

untreated fruits (Picchion et al., 1998). Furthermore, Senevirathna and Daundasekera

(2010) found a positive relationship between tomato fruit firmness and calcium

chloride concentration treatment.

The loss of firmness in storage might be due to the breaking of insoluble protopectin

into soluble pectin (Matto et al., 1975) led to increased membrane permeability

(Oogaki et al., 1990). The increase in cell membrane permeability might be due to

hydrolysis of intercellular pectins and reduction in cell turgor pressure. These factors

resulted a decrease in tissue rigidity and increase in fruit softening, hence fruit

firmness decreased (Pollard, 1974). The exogenous calcium application, cross linked

the deastrified pectin chain thereby forms a tighter and firmer structure (Grant et al.,

1973).

Total soluble solids (TSS), a major quality attribute, correlates with the composition

and texture (Peck et al., 2006; Weibel et al., 2004). TSS gives an estimation of the

93

amount of soluble minerals and sugars present in the fruit. The percentage of sugars

present in soluble solids contents are about 80-85% (Peck et al., 2006). In the current

study, total soluble solids and TSS-acid ratio both retained up to the maximum (9.02

and 6.59%) in fruits treated with 1% calcium of calcium chloride source.

As the fruit proceeds to ripening process, the degradation of polysaccharides to simple

sugars occurs that might increase TSS content (Naik et al., 1993) of the fruits.

Calcium is one of the major nutrients that slow down the respiration and other

metabolic activities of the fruit, which retards the ripening process. Furthermore,

reduction in respiration rate resulted to slow down the synthesis and utilization of

metabolites that eventually decrease the conversion of carbohydrates to sugars which

ultimately lowers the TSS content of fruit (Rohani et al., 1997). The present results

are confirmed by Cheour et al. (1991), who observed that application of calcium

basically delayed the increase in free sugars of fruits, which steadily increased in

storage. The pre-harvest calcium application increased the calcium content and

retained the fruit TSS content, hence regulated various postharvest changes that led to

senescence (Cheour et al., 1990).

Weight loss and Brown rot incidence

Findings of the current research showed that peach fruits treated with 1% calcium of

calcium chloride solution significantly reduced the physiological weight loss and

brown rot incidence by 18.23 and 18 %, respectively. Calcium is a major mineral

constituent of middle lamellae (Dey and Brinson, 1984). During ripening process,

weakening of middle lamellae occur which resulted in softening of fruits and

increased the weight loss (Dey and Brinson, 1984). Calcium helps in binding

polygalacturonic acid with each other thus making the membrane structure strong and

rigid. Previous studies showed that application of calcium reduced the post harvest

disorders and improved the shelf life of horticultural commodities. Calcium delayed

the rate of respiration and transpiration resulting in delayed senescence in peach fruits

(Sharma et al., 1996). Lester and Grusak (1999) reported that calcium lowered down

94

losses of protein, phospholipids and ion leakage from fruits. This is the major factor

behind the weight loss and loosing the membrane functionality and integrity. Calcium

application was found effective in terms of membrane functionality and integrity

maintenance (Lester and Grusak, 1999). Izumi and Watada (1994) treated the carrot

fruits with calcium chloride significantly retained the weight loss and improved the

texture of the fruits and thereby extended the post-harvest.

The inhibitory effect of calcium chloride is attributed probably to decrease weight loss

and also increase resistance of tissue to the attack of microorganisms (Berry et al.,

1998). Calcium chloride significantly decreased weight loss of peach fruits as calcium

reduces the rate of transpiration and delays the dehydration during cold storages

(Sohail et al., 2015).

The present results showed reduction of disease incidence (Brown rot) with the

application of Ca source and its concentration. Brown rot incidence of peach

decreased by 29.94 and 18.06 %, respectively in fruits treated with 1% concentration

of calcium chloride, respectively as compared to unfertilized fruits and other

treatments of calcium. This might be due to the fact that application of CaCl2 at the

highest concentration resulted in maximum uptake of calcium. Injury caused by

oxidation of membrane, mixes the oxidizable substrates (polyphenols) and separated

enzymes, which results in browning of fruits (Hodges, 2003). Calcium minimized

fungicide sprays and act as a precursor of fungicidal sprays (Lester and Grusak, 2004).

As browning is directly related with calcium in fruits, so applying calcium at an

optimum level significantly reduced the disease incidence and chilling injury in peach

(Hewajulige et al., 2003). Other reasons for the decrease of brown rot incidence might

be the role of calcium in membrane stability that would help the fruits to resist against

diseases (Poovaiah, 1988 and Picchioni et al., 1995). Stimulation of phytoalexins

(Kohle et al., 1985) and minimization of fungal polygalacturonase enzymes (Conway

and Sams, 1984) is also due to the application of calcium. This results in disease

resistance, by making cross bridges of cations between pectin acid in cell wall of the

95

plant. The application of calcium chloride to peach fruit encouraged

polyphenoloxidase levels, hence improved the fruit cell wall calcium content (Souza

et al., 1999, 2001). The increase in calcium content increased natural sugars and also

reduced cell wall pectin esterification, which led to decrease in infected areas with

brown rotting and disease index compared with control fruits. The pre harvest calcium

spray helps in minimizing the physiological weight loss, respiration, decay of

naturally infected fruits and improving other post-harvest attributes of peach (Singh et

al., 1982; Bhullar et al., 1981; Gautam et al., 1981). Similarly the application of

CaCl2 significantly reduced the incidence and severity of brown rot in peach

(Thomidis et al., 2007).

Fruit calcium content

The application of 1% calcium chloride as foliar spray, significantly increased the

fruit calcium content by 9.83 (1% Ca) and 15% (CaCl2), respectively as compared to

control and other calcium treatments.

The major factors responsible for the non-availability of calcium to plants are soils

having high pH and due to the immobility of calcium in plant body. Therefore, pre

and post-harvest application calcium is very important to overcome the calcium

related deficiency and disorders (Dewey, 1980). The most suitable source for

increasing calcium content in fruits is calcium chloride (Raese and Drake, 2002)

which greatly confirmed the present results (Table 5.3). Calcium depends on natural

openings like stomata, cracks and lenticels to enter the peel of the fruit (Harker and

Ferguson, 1988). Recent studies suggested that different compounds are produced by

foliar application of calcium which increases the upake of calcium with minimum

surface damage (Lester and Grusak, 2004). Calcium application helps the fruit to

protect it against cell wall degrading enzymes by making the cell wall stable (White

and Broadley, 2003). Previous studies revealed that senescence of the plant is closely

related with calcium status of the tissue. Optimum calcium concentration reduces

plant degradation processes like protein content, fluidity of membranes and

96

respiration rate (Poovaiah, 1986).

Calcium application to plants increases the resistance to abiotic stresses (White and

Broadly, 2003) as well as many other physiological stresses (Bangerth, 1979). It also

helps to reduce the production of ethylene and respiration rate in many fruits

including peach (Garcia et al., 1995).

Calcium helps in building cell wall and membrane structure. It is also a co-factor of

enzymes, mainly used for the metabolism of nitrogen (Thompson and Fry, 2000).

Calcium minimizes solubilization of pectin (Dey and Brinson, 1984) and cellular

turgor loss (Hussain et al., 2008) and that’s why regarded as softening-inhibiting ion

(Hussain et al., 2012). It also plays a vital role in strengthening the cell wall by

making cross bridges and interacting with pectic acid polymers (Bassi et al., 1998).

The present results are in close conformity with the results of Lara et al. (2004), who

observed that 1% CaCl2 delayed fruit ripening, sustained structural integrity in

strawberry and make the fruit resistant against fungal attack.

Cell wall and membrane ion leakage

Cell membrane ion leakage decreased by 24.04 and 24%, respectively in fruits treated

with 1% calcium concentration and calcium chloride used as source of calcium

respectively as compared to control and other calcium treatments. Similarly, ion

leakage from cell wall reduced up to 16.59 and 24%, respectively in fruits treated with

calcium at 1% and calcium chloride source of calcium.

Cell wall and cell membrane ion leakage are key factors, which causes a surge of

biochemical reaction, during postharvest physiological changes (Marangoni et al.,

1996). Fruit plants especially peach are sensitive to (Tareen et al., 2012) chilling

injury when exposed to low temperature below 10 oC but above freezing temperature

(Saltveit and Morris, 1990). Chilling temperature gradually shows various signs like

enhanced loss of water, ion leakage, abnormal ripening, production of ethylene and

susceptibility to disease but develop rapidly in fruits that are transferred from chilling

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550893/#CR17

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550893/#CR28

https://www.ncbi.nlm.nih.gov/pubmed/?term=Hussain%20PR%5BAuthor%5D&cauthor=true&cauthor_uid=23904650

97

to non-chilling condition (Saltveit et al., 2004). Changes in protein (Hausman et al.,

2000) and membrane structure resulted in increased permeability and ion leakage

which are some of the characters of chilling injury (Friedman and Rot, 2006).

Various techniques like heat treatment, atmosphere with high CO2 and low oxygen

during chilling, high humidity storage and foliar application or dipping in calcium are

employed to minimize ion leakage in fruits and vegetables (Saltveit et al., 2004).

Adjustment of fatty acid in membrane should be done to minimize ion leakage as

chilling temperature targets and affects the crucial membranes of plants. Calcium is

involved in cell wall and cell membrane stability, which decreases the ion leakage and

in turns delays the senescence process of the plants (Mortazavi et al., 2007;

Rubinstein, 2000 and Torre et al., 1999). Meng et al. (2009) reported that low ion

leakage due to minimum distraction of plasma lemma membranes. Moreover,

Demarty et al. (1984) also quoted the significance of calcium in improving the

cohesion of cell membrane which led to the decrease in electrolyte leakage. Cell wall

tightening by Ca++

is due to cross linking between pairs of negatively charged

homogalacturonans. In cold storages, more calcium present in the cytoplasm enhances

the tolerance of cell against cold stress because, calcium ion has the capability to

travel in and across vacuole and cytoplasm (Picchion et al., 1998). Several researcher

have mentioned the importance of calcium in minimizing the ion leakage in peaches

(Wade, 1981), avocado (Chaplin and Scott, 1980) and tomatoes (Moline, 1994).

Furthermore, Lester and Grusak (1999) also reported the role of calcium in

maintaining integrity of cell wall and membrane with minimum losses in

phospholipids and protein. All these factors reduce the ion leakage and post harvest

losses which in turned increase shelf life of plum. Similarly, Application of calcium

chloride minimized ion leakage in loquat in cold storages (Akhtar et al., 2010) and

minimizes browning index in pomegranate, a typical sign of chilling injury

(Mirdehghan and Ghotbi, 2014).

Calcium also has a pronounced effect in minimizing the senescence of plant cells by

98

controlling membrane stability (Rubinstein, 2000; Torre et al., 1999). Moreover,

integrity and stability of cell wall is also increased by reducing electrolyte leakage

(Mortazavi et al., 2007). Previous research showed that 3% CaCl2 had the lowest

relative electrolyte conductance compared to untreated fruits. Increment in cell

membrane cohesion and integritiy of plasma membrane resulted in lower electrical

conductivity from the fruits (Demarty et al., 1984).

99


Summary

The experiment was conducted at Hort. Research Farm and Postharvest Horticulture

Laboratory, UAP with the objective to find out the best calcium source and its

optimum level for retaining the quality and shelf life of peach. The experiment was

carried out in two phases. During the first phase, peach fruits were sprayed with

different source of calcium (Calcium chloride, Calcium nitrate and calcium sulphate)

and their concentration (0.5, 0.75 and 1.0%) along with a single control at plateau

stage. The experiment was conducted by using RCB Design with 2 factors replicated

3 times. Three trees were assigned to each treatment. For this purpose uniform sized

trees were selected randomly for each treatment. During the second phase, the

harvested fruits were brought to Post harvest laboratory, Horticulture Department to

study the effect of calcium sources and their concentrations on storage performance of

peach fruit for 30 days at temperature of 8±2 with relative humidity of 50%.

Various growth attributes of peach i.e. firmness (kg.cm-2

), TSS (°brix), percent acidity,

TSS-acid ratio, ascorbic acid content (mg 100g-1

), reducing and non reducing sugars

(%), brown rot incidence (%), weight loss (%), fruit calcium content (%), ion leakage

from cell membrane and cell wall (%) were studied.

The analyzed data revealed that all the quality and mineral attributes of peach was

significantly affected by various calcium sources. More fruit firmness (5.57 kg cm2),

fruit calcium content (9.38%), less TSS (8.57 °brix), TSS-acid ratio (12.62), brown rot

incidence (14.83%), weight loss (14.81%), ion leakage from cell membrane (37.19%)

and cell wall (20.33%) were recorded in fruits of the plant treated with foliar

application of calcium chloride solution. Peach fruit trees sprayed with calcium nitrate

solution showed the lowest fruit firmness (5.35 kg cm2), fruit calcium content (7.53%),

more TSS (9.37 °brix), TSS-acid ratio (13.79), brown rot incidence (19.23%), weight

loss (18.31%), ion leakage from cell membrane (44.25%) and cell wall (23.76%).

100

The highest firmness (5.69 kg.cm2), fruit calcium content (9.11%), less TSS

(8.26 °brix), TSS-acid ratio (11.48), brown rot incidence (14.15%), weight loss

(14.76%), ion leakage from cell membrane (37.28%) and cell wall (20.92%) were

recorded in fruits of the plant treated with foliar application of 1% calcium solution.

Less fruit firmness (5.20 kg cm2), lower fruit calcium content (7.98%), higher TSS

(9.44 °brix), TSS-acid ratio (14.27), brown rot incidence (19.59%), weight loss

(18.07%), ion leakage from cell membrane (44.42%) and cell wall (24.93%) were

recorded in fruits sprayed with 0.5% calcium solution.

The means for storage duration showed that freshly harvested peach fruits showed the

highest fruit firmness (5.69 kg cm2), acidity (0.76%), vitamin C content (6.40

mg.100g-1

), non-reducing sugars (4.40%), lowest TSS (8.67 0brix), TSS-acid ratio

(11.94), reducing sugar (1.38%), ion leakage from cell wall and cell membrane (41.55

and 20.08% respectively). While the lowest brown rot incidence (10.61%) and

weightloss (16.12%) were recorded in peach fruits stored for 10 days. The means for

storage duration showed that lowest fruit firmness (4.78 kg cm2), acidity (0. 64%),

vitamin C content (5.94 mg.100g-1

), non-reducing sugars (4.02%), highest TSS (9.99

0brix), TSS-acid ratio (15.98), reducing sugar (2.23%), ion leakage from cell wall and

cell membrane (48.46 and 27.44% respectively), brown rot incidence (13.94%) and

weightloss (23.80%) was noted in peach fruits at 30th

day of storage.

All two and three way interactions were found were found non-significant except

calcium source and calcium concentration interaction which was found significant for

most of the studied attributes.

101

Conclusions

Based on the present findings, it is concluded that

Among the calcium sources, foliar application of calcium chloride retained

firmness, TSS and TSS-acid ratio and lowered brown rot incidence, weight loss,

ion leakage from cell membrane and cell wall of peach compared with other

sources of calcium

A significant variation was also observed among the different calcium

concentration. 1.0% calcium solution proved to be the best in terms of fruit

firmness, TSS, TSS-acid ratio, fruit calcium content while lowered the brown rot

incidence, weight loss, ion leakage from cell membrane and cell wall in peach

Fruit calcium content was non-significantly affected by storage durations

The effect of calcium sources and concentrations on quality attributes such as

ascorbic acid content, percent acidity, reducing and non reducing was found

non-significant

Recommendation

The following recommendation is made with the above mentioned conclusions

The peach trees cv. Early Grand could be foliarly sprayed with 1.0% CaCl2 to

retain the maximum quality attributes during storage up to 30 days at Temp

8±2 0C with RH 50%

102

CHAPTER VI

EFFECT OF 1-METHYLCYCLOPROPENE (1-MCP)

CONCENTRATIONS ON STORABILITY OF PEACH FRUIT CV.

EARLY GRAND




ABSTRACT

An experiment entitled “Effect of 1-Methylcyclopropene (1-MCP) concentrations on

storability of Peach fruit cv. Early Grand” was carried out at Horticulure Research

Farm and Post-harvest Lab, Horticulture Deptt., UAP in the year 2015. Peach fruit

trees were fertilized with pre harvest foliar spray of calcium chloride at 1%

(optimized from the previous experiment of 2014). The treated fruits were brought to

Post harvest Lab and dipped in various concentrations of 1-MCP (0, 0.3, 0.6 and 0.9

µg L-1

), stored for 40 days at 8+2 0C with 50% relative humidity (RH) and analyzed

the fruits for various physico-chemical attributes with 10 days interval. The

experimental results showed that 1-MCP significantly affected all the studied

attributes. The lowest weight loss (10.53%), fruit decay (11.13%), total soluble solids

content (8.79 °Brix), TSS-acid ratio (12.15), highest fruit firmness (5.61 kg cm-2

),

acidity (0.73%), ascorbic acid (6.19 mg 100g-1

), reducing sugars (1.79%) were

recorded in fruits treated with 0.6 µg L-1

1-MCP solution, while, the highest free

radical scavenging assay (75.22 %), catalase activity (46.93 U g-1

FW), total phenols

(75.92 mg GAE 100 g-1

) and antioxidant activity (65.86 mg kg-1

) were recorded in

fruits treated with 0.9 µg L-1

1-MCP solution. The lowest non reducing sugars (3.97%)

were observed when fruits were treated with 0.3 µg L-1

1-MCP solution. Storage

duration had also a significant effect on the studied attributes. The lowest weight loss

(14.77%) and fruit decay (15.27%) were observed in fruits at 10 day storage. The

lowest total soluble content (8.45 °brix), TSS-acid ratio (11.15), highest fruit firmness

(5.83 kg cm-2

), acidity (0.76%) and reducing sugars (1.40%), highest ascorbic acid

(6.25 mg/100g) and non reducing sugars (4.17%) were observed in control group of

fruits. Fruits stored for 30 days showed more free radical scavenging assay (77.50 %),

catalase activity (50.75 U g-1

FW), total phenols (79.86 mg GAE 100 g-1

) and

antioxidant activity (67.75 mg kg-1

). It is concluded that peach fruits could be treated

with 0.6 µg L-1

1-MCP solution for prolonging the shelf life of peach up to 40 days

under low temperature (8+2 °C with 50% RH).

103

INTRODUCTION

Peach, being highly perishable, is given less attention by the peach growers and hence

has short post harvest life (Khan et al., 2016). Various physical, biochemical and

physiological changes are involved during the fruit ripening process. These changes

leads to increase the respiration rate, ethylene production, aroma development, color,

texture, organic acids, aromatic and volatile substance (Remorini et al., 2008), thus

peach fruits results in very short post harvest life usually 3-4 days when kept at ambient

temperature (Wills et al., 2007). The post harvest losses in horticultural crops ranged

from 17-40% (Rind, 2003). The post-harvest losses in peach are about 23% (Khan,

2012). During the ripening process, peach fruit exhibits a rise in ethylene production

due to increased respiratory activities (Brovelli et al., 1998). All these factors results in

variation of textural firmness, skin color, sugar content and phenolic compounds

(Cascales et al., 2005).

Number of biological and chemical practices is used to enhance the storage life of

peach fruit throughout the world. Among these techniques, addition of

1-methylcyclopropene (1-MCP) to the list has given a new way to post harvest

technologist to extend the shelf life of any commodity (Blankenship and Dole, 2003).

Previous researches suggested that 1-MCP slowed down the decline in protein content

of senescing coriander leaves (Jiang et al., 2002b). Being an ethylene inhibitor,

1-MCP extends individual flower longevity, improves protein content and fresh

weight but there was no effect on lipid fluidity compared with control (Serek et al.,

1995). Recent studies showed that application of 1-MCP before exposing the fruits to

ethylene greatly delayed the fruit ripening (Apelbaum et al., 2008; Zhang et al., 2009,

2010).

104

Keeping in view the perishability of peach, its short post harvest life and the

effectiveness of 1-MCP in reducing postharvest losses and retaining the quality

attributes in peach, the present experiment was designed to accomplish the following

objectives.

To find out the optimum concentration of 1-MCP to retain the biochemical

attributes of peach fruit during storage

To findout the interactive effect of 1-MCP and storage days on storage

performance of peach fruits

105


To improve storability of peach fruits, an experiment entitled “Effect of

1-Methylcyclopropene (1-MCP) concentrations on the storability of Peach fruit cv.

Early Grand” was undertaken in Post harvest, laboratory, Horticulture and

Agricultural Chemistry Department UAP, Peshawar in the year 2015.

Calcium source and concentration were optimized form the previous year experiment

2014. Peach fruit trees of cultivar Early Grand were foliar sprayed with 1% CaCl2

solution. The harvested fruits were brought to the post-harvest laboratory of

Horticulture Department for analysis of various physico-chemical attributes.

Harvesting of peach fruits was done at physiologically matured stage from orchad of

peach fruits, Horticulture Department, UAP during the year 2015. After harvesting,

fruits of uniform maturity and size was taken and brought of Post harvest, Laboratory,

Horticulture Department for research purpose.

The fruits were then washed with tap water to remove any remaining material selected

fruits, air dried and then properly placed according to CR Design repeated three times.

Fruits were dipped in different concentrations of 1-MCP (0, 0.3, 0.6 and 0.9 µg L-1

)

for 5 minutes (Argenta et al., 2007) and stored for 40 days at 8+2 0C with 50% relative

humidity (RH) and analyzed the fruit samples for various physico-chemical attributes

with 10 days of interval.

Studied attributes

To study the effect of 1-MCP on the post harvest life of peach, the following various

physico-chemical attributes were recorded.

The procedure for determining weight loss (%), fruit firmness (kg.cm-2

), TSS (°brix),

acidity (%), TSS-acid ratio, ascorbic acid (mg.100g-1

), reducing non reducing Sugar

(%) is already given in experiment 1 (Chapter 3) and experiment 3 (Chapter 5).

Fruit decay (%)

The fruit decay in each treatment and replication was checked on the regular basis and

fruits with symptoms of fruit decay was noted and percentage fruit decay was

106

calculated with the given formula.

DPPH Free Radical Scavenging Assay (%)

The procedure used by Jain et al. (2008) was followed for calculating DPPH free

radical scavenging assay (FRSA). Spectrometer was run initially using methanol as

blank sample which was then followed by taking peach extract of 0.5 ml. 2 ml DPPH

solution that consisted of 0.2mM methanol concentration was poured to each sample.

After that all the samples were incubated for 30 minutes at room temperature. Using

spectrophotometer, all the samples were analyzed against blank when the obsorbance

reached to 517nm. FRSA or free radical inhibition (I%) was calculated with the help

of the given formula

Catalase activity (Unit g-1

protein)

The procedure used by Abbasi et al. (1998) was followed for the measuring catalase

activity of peach fruits. 2.9 ml of 15M KPO4 buffer solution (pH=7) and 2.9 ml of

12.5mM hydrogen peroxide buffer solution (pH=7) was used for preparing buffer A

and B solution. Both these solutions were separetly taken in two different cuvettes and

an enzyme extract of 100 µL were poured in these cuvettes seperatly which were kept

in a gloomy box. After 45 and 60 seconds, the optical density at 240nm of both the

curvettes were noted by using spectrophotometer of Optima® 3000 plus. Readings

were recorded for computing the catalase activity of peach fruits.

Total phenolics content (mg of (GAE) per 100 g of dry matter)

Total phenols was determined by using the procedure given by Piga et al. (2003)

using FolinCiocalteu reagent (Slinkard and Singleton, 1977). A composite sample of

5 g was prepared from 5 different peach fruits in each treatment and replication which

were placed in a centrifuge (4000 x g for 15 minutes) followed by filteration.

107

Incubation of a mixture prepared, containing 5 ml Folin-Ciocalteu reagent, 1 ml

sample, 7% Na2CO3 with distall water was done for 1 hour. When the absorbance

reached to 760nm against blank, readings were noted. A standard curve of phenolic

content was drawn by using a standard solution of Gallic acid. Before running the

procedure, gallic acid solution was calibrated and were computed using following

formula:

C = c. V/m

Where: C = Phenolics compound (mg g-1

plant extract) in GAE

c = Calibration curve established for gallic acid (mg/mL)

V = volume of extract (mL)

m = Fruit pulp weight (g)

Anitoxidant activity of the Fruit (mg kg-1

)

For measuring antioxidant activity, the procedure of given by Zhang et al. (2015) and

Turkoglu et al. (2006) using DPPH (2,2-Diphenyl-1-Picrylhydrazyl). The pulp of 5

randomly peeled peach fruits was taken and kept in storage at -80 °C in separate bags

before analysis. Before extraction, the samples were taken out from storage and kept

for 10 minutes at room temperature. A mixure of 10 g of sample and 50 ml methanol

was prepared shaked for 30 seconds. The prepared sample were then centrifuged at

15000 RPM for 15 minutes and Then 10 g of fruit pulp was taken separately from

each sample bag and mixed with 50 ml of 50% methanol and were homogenized for

30 seconds. All the sample solutions were centrifuged at 15,000 RPM for 15 minutes

and mixture was taken for antioxidant analysis

Statistical analysis:

The data recorded was arranged according to Completely Randomized Design and

was subjected to Analysis of Variance technique as given by Jan et al. (2009). It was

then analyzed using statistical software Statistix 8.1 (Statistix_8 Analytical Software,

2003). If data was found significant, Least Significant Difference (LSD) test was

applied for mean comparison.

108

RESULTS

Fruit Firmness (kg cm-2

)

The mean data of Table 6.1 showed that 1-MCP, storage duration and their

interactions had a significant effect on firmness of peach fruits.

Regarding the means for 1-MCP levels, more firmness (5.61 kg.cm-2

) was recorded in

peach fruits dipped in 0.6 µg L-1

1-MCP solution while the peach fruits in control

group showed the lowest fruit firmness (4.89 kg cm-2

).

More firmness (5.83 kg cm-2

) of peach fruits was found in freshly harvested peach

fruits. Minimum firmness (4.28 kg cm-2

) of peach fruits was observed, when fruits

were kept up to the highest day of storage i.e. 40 days.

More firmness (6.30 kg cm-2

) of peach fruits was found in fruits treated with 0.6 µg

L-1

harvested as fresh. Minimum firmness (4.00 kg cm-2

) of peach fruits was recorded

in control group of fruits stored up to day 40th

(Fig 6.1).

Total Soluble Solids (0brix)

1-MCP and storage duration had a pronounced effect on TSS of peach fruits while

their interaction was found non-significant (Table 6.1).

The highest TSS content (9.28 °brix) was recorded in peach fruits of control treatment

while peach fruits treated with 0.6 µg L-1

showed the lowest TSS (8.79 0Brix) content.

Regarding the means of storage duration, increasing storage days from 0 (fresh) to 40

days significantly increased TSS content from 8.45 to 9.96 0brix.

Percent acidity (%)

Significant variation was observed for 1-MCP levels and storage duration on percent

acidity of peach fruits while their M×SD had a non-significant effect on titratible

acidity of peach fruits (Table 6.1).

Peach fruits dipped in 0.6 µg L-1

1-MCP solution showed the highest value for percent

acidity (0.73%), followed by percent acidity (0.70%) noted in fruits treated with 0.3

µg L-1

1-MCP while the lowest percent acidity (0.68%) was observed in peach fruits

of control treatment and 0.9 µg L-1

of 1-MCP.

109

Regarding means for storage duration, percent acidity ranged from 0.76 to 0.63% in

peach fruits from 0 to 40 days of storage

TSS-acid ratio

The data for TSS-acid ratio showed that various levels of storage days and 1-MCP

showed their effect on TSS-acid ratio while their interaction was found

non-significant (Table 6.1).

The highest TSS-acid ratio (13.78), observed in untreated fruits of peach with 1-MCP.

0.6 µg L-1

treated with 1-MCP recorded minimum TSS-acid ratio (12.15) peach fruits.

Regarding the means for storage duration, the more TSS-acid ratio (15.89) was found

in peach fruits of 40 days. The data taken from fruits at 0 day storage had the highest

TSS-acid ratio (12.06) as compared to rest of treatments.

Ascorbic acid content (mg/100g)

Ascorbic acid of peach fruits was significantly influenced by the post-harvest

application of 1-MCP concentrations, storage durations and their interaction (Table

6.1).

Regarding the means for 1-MCP levels, increasing the concentration of 1-MCP from 0

to 0.6 µg L-1

significantly increased the ascorbic acid from 6.03 to 6.19 mg.100g-1

that

declined to 6.11 mg.100g-1

, in 0.9 µg L-1

treated 1-MCP peach fruits.

The highest vitamin C (6.25 mg.100g-1

) content was recorded in control peach fruits,

followed by vitamin C contents (6.22, 6.15 and 6.05 mg.100g-1

) noted in fruits at 10,

20 and 30 days storage, respectively. While peach fruits kept for 40 days in storage

showed the lowest ascorbic acid (5.88 mg 100g-1

) content.

More vitamin C content (6.31 mg.100g-1

) content of peach fruits was observed in

fruits of control treatment, dipped in 0.6 µg L-1

1-MCP solution. The lowest vitamin C

content (5.73 mg.100 g-1

) was noted in untreated peach fruits kept in storage for 40

days (Fig 6.2).

110

Table 6. 1: Fruit firmness (kg.cm-2

), TSS (0brix), Percent acidity (%), TSS-acid

ratio and ascorbic acid (mg.100g-1

) of peach fruit as affected by

1-MCP levels during storage.

1-MCP (M)

(µg/L)

Parameters

Fruit Firmness

(kg cm-2

)

Total soluble

solids (0brix)

Percent

acidity (%)

TSS-acid

ratio

Ascorbic acid

(mg 100g-1

)

0 4.89 d 9.28 a 0.68 c 13.78 a 6.03 c

0.3 5.15 c 9.07 b 0.70 b 13.15 b 6.12 b

0.6 5.61 a 8.79 d 0.73 a 12.15 c 6.19 a

0.9 5.27 b 8.94 c 0.68 c 13.24 b 6.11 b

LSD (P≤ 0.05) 0.07 0.07 0.01 0.20 0.025


Control 5.63 b 8.60 e 0.71 b 12.06 d 6.25 a

10 5.83 a 8.45 d 0.76 a 11.15 e 6.22 b

20 5.30 c 8.81 c 0.71 b 12.39 c 6.15 c

30 5.09 d 9.27 b 0.67 c 13.92 b 6.07 d

40 4.28 e 9.96 a 0.63 d 15.89 a 5.88 e

LSD (P≤ 0.05) 0.08 0.08 0.01 0.22 0.028

Interaction at LSD (P≤ 0.05)

MxSD Fig 6.1 --- --- -- Fig 6.2

Significance * Non Sig. Non Sig. Non Sig. ***


another


respectively.

111

Storage duration (days)

Control 10 20 30 40

Fru

it fir

mne

ss (

kg

cm

-2)

3.5

4.0

4.5

5.0

5.5

6.0

6.5

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6.1: Effect of 1-MCP and storage duration Interaction on fruit firmness (kg

cm-2

) of peach


Control 10 20 30 40

Asco

rbic

acid

co

nte

nt (m

g 1

00

g-1

)

5.6

5.7

5.8

5.9

6.0

6.1

6.2

6.3

6.4

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6.2: Effect of 1-MCP and storage duration Interaction on ascorbic acid (mg

100g-1

) of peach

112

Reducing sugars (%)

Storage days, 1-MCP levels and their interaction had a significant on reducing sugars

of peach fruits (Table 6.2).

Regarding the means for 1-MCP concentrations, peach fruits dipped in 0.6 µg L-1

1-MCP solution recorded more reducing sugars (1.79%), followed by reducing sugars

(1.75 and 1.74%) of peach fruits treated with 0.3 and 0.9 µg L-1

respectively. However,

the lowest reducing sugars (1.72%) were recorded in peach fruits of control treatment.

More reducing sugars (2.16%) were observed in peach fruits kept in storage for 40

days The lowest reducing sugars (1.40%) were observed in peach fruits at 0 day

storage.

The interactive effect of 1-MCP concentration and storage duration revealed that more

reducing sugars (2.19%) were recorded in peach fruits dipped in 0.9 µg L-1

1-MCP

concentration, stored for 40 days. The lowest reducing sugar (1.32%) was noted in

peach fruits at 0 day storage of control treatment (Fig 6.4).

Non-reducing sugars (%)

1-MCP levels, storage days and their interaction, significantly influenced non

reducing sugars of peach fruits (Table 6.2).

The highest non reducing sugars (4.04%) were recorded in peach fruits of control

treatment, followed by non reducing sugars (4.02%) in peach fruits dipped in 0.9 and

0.3 µg L-1

1-MCP solution. However, the lowest non reducing sugar (3.99%) was

recorded in peach fruits dipped in 0.6 µg L-1

1-MCP solution.

Regarding the means of storage duration, a decrease in non reducing sugars from 4.17

to 3.86% was observed with increasing storage days from 0 to 40 days.

Pertaining the interaction between 1-MCP levels and storage durations, the highest

non reducing sugars (4.22%) were observed peach fruits at 0 day storage, dipped in

0.9 µg L-1

1-MCP solution, whereas the lowest non reducing sugars (3.80%) were

observed in peach fruits dipped in 0.6 µg L-1

1-MCP solution, kept for 40 days in

storage (Fig 6.5).

113

Weight loss (%)

The effect of storage duration, 1-MCP levels and their interaction was found

significant for weightloss of peach fruits (Table 6.2).

Regarding the means for 1-MCP levels, maximum weight loss (6.01%) was observed

in untreated peach fruits with 1-MCP. The lowest weight loss (5.55%) was observed

in peach fruits dipped in 0.6 µg L-1

1-MCP solution.

The highest loss of weight (10.19%) in peach fruits was observed in 40 days storage.

The lowest weight loss (4.27%) was recorded in peach fruits stored for 10 days.

The interactive effect of 1-MCP concentration and storage duration was also found

significant. The highest weight loss (10.33%) was observed in peach fruits stored for

40 days, dipped in 0.3 µg L-1

1-MCP solution. The lowest weight loss (4.00%) was

observed in peach fruits treated with 0.6 µg L-1

1-MCP solution, stored for 10 days

(Fig 6.6).

Fruit decay (%)

Significant variation was observed among the different treatment of 1-MCP, storage

days and their interaction regarding fruit decay of peach fruits (Table 6.2).

The highest percentage of fruit decay (7.41%) was recorded in peach fruits of control

treatment. The lowest percent fruit decay (6.95%) was recorded in peach fruits dipped

in 0.6 µg L-1

1-MCP solution.

As concerned the means for storage durations, peach fruits stored for 40 days showed

maximum fruit decay (11.69%) as compared to fruit decay (6.27%) at 10 day storage.

More fruit decay (11.83) was observed in peach fruits dipped in 0.3 µg L-1

, stored for

40 days. The lowest fruit decay (6.00%) was observed in peach fruits dipped in 0.6 µg

L-1

1-MCP solution, stored for 10 days (Fig 6.7).

114

Table 6. 2: Reducing sugars (%), non reducing sugars (%), weight loss (%) and

fruit decay (%) of peach as affected by 1-MCP levels during storage

1-MCP (M)

(µg/L)

Parameters

Reducing

sugars (%)

Non Reducing

sugars (%)

Weight loss

(%)

Fruit decay (%)

0 1.72 c 4.04 a 6.01 a 7.41 a

0.3 1.76 b 3.97 b 5.87 b 7.27 b

0.6 1.79 a 4.02 bc 5.55 d 6.95 d

0.9 1.74 b 4.02 c 5.73 c 7.13 c

LSD (P≤ 0.05) 0.02 0.02 0.08 0.08


Control 1.40 e 4.17 a 0.00 e 0.00 e

10 1.63 d 4.07 b 4.27 d 6.27 d

20 1.67 c 4.01 c 6.23 c 8.73 c

30 1.91 b 3.95 d 8.26 b 9.26 b

40 2.16 a 3.86 e 10.19 a 11.69 a

LSD (P≤ 0.05) 0.02 0.02 0.09 0.09


MxSD Fig. 6.4 Fig. 6.5 Fig. 6.6 Fig. 6.7

Significance * *** *** ***


another


respectively.

115


Control 10 20 30 40

Re

ducin

g s

ug

ars

(%

)

1.2

1.4

1.6

1.8

2.0

2.2

2.4

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6. 3: Effect of 1-MCP and storage duration interaction on reducing sugars

(%) of peach fruits


Control 10 20 30 40

No

n r

ed

ucin

g s

ug

ars

(%

)

3.7

3.8

3.9

4.0

4.1

4.2

4.3

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6.4: Effect of 1-MCP and storage duration interaction on non-reducing

sugars (%) of peach fruits

116

Storage duration (day)

Control 10 20 30 40

we

ight lo

ss (

%)

-5

0

5

10

15

20

25

30 0

0.3

0.6

0.9

Fig 6.5: Effect of 1-MCP and storage duration Interaction on weight loss (%) of

peach fruits

Storage duration (day)

Control 10 20 30 40

Fru

it d

eca

y (%

)

-5

0

5

10

15

20

25 0

0.3

0.6

0.9

Fig 6.6: Effect of 1-MCP and storage duration interaction on fruit decay (%)

incidence of peach fruits

117

Free Radical Scavenging Assay (%)

Different levels of 1-MCP, storage durations and their interaction significantly

affected free radical scavenging assay of peach fruits (Table 6.3).

The data recorded for free radical scavenging assay revealed that more activity of free

radical scavenging (75.22 %) was recorded in peach fruits dipped in 0.8 µg L-1

1-MCP solution followed by free radical scavenging assay (74.48 and 74.33 %)

observed in peach fruits dipped in 0.6 and 0.3 µg L-1

1-MCP solution. However, the

lowest activity of free radical scavenging assay (72.96 %) of peach fruits was

recorded in control treatment.

The highest free radical scavenging assay (77.50 %) was recorded in peach fruits

stored for 30 days. The lowest free radical scavenging assay (69.79 %) was observed

in peach fruit kept in storage for 0 days.

The interaction between 1-MCP and storage duration showed that the highest activity

of free radical scavenging assay (78.63 %) was recorded in peach fruits dipped in 0.9

µg L-1

1-MCP solution, stored for 30 days. The lowest free radical scavenging assay

(68.55 %) was recorded in peach fruit at 0 day storage of control treatment (Fig 6.7).

Catalase activity (U g-1

FW)

Catalase activity of peach fruits was significantly affected by storage days, 1-MCP

levels and their interaction (Table 6.3).

The data for 1-MCP levels showed that more catalase activity (46.93 U g-1

FW) was

recorded in peach fruits dipped in 0.9 µg L-1

. The lowest catalase activity (41.93 U g-1

FW) was observed in peach fruits of control treatment.

Regarding the means for storage duration, the highest catalase activity (47.75 U g-1

FW) was recorded in peach fruits stored for 30 days followed by catalase activity

(46.42 U g-1

FW) in peach fruits kept for 20 days in storage. While peach fruits of 0

day storage showed the lowest catalase activity (34.27 U g-1

FW).

Regarding the means for the interactive effect of 1-MCP concentration and storage

duration, more catalase activity (51.63 U g-1

FW) was recorded in peach fruits dipped

118

in 0.9 µg L-1

stored for 30 days, while the lowest catalase activity (34.11 U g-1

FW)

was recorded in peach fruits of 0 day storage of control treatment (Fig 6.8).

Total phenols (mg GAE 100 g-1

)

A significant effect was observed for phenolic content of peach fruits by storage days,

1-MCP levels and their interaction (Table 6.3).

Regarding the means for 1-MCP levels, increasing 1-MCP levels from control to 0.9

µg L-1

significantly increased the total phenolic content of peach fruits from 68.08 to

76.02 mg GAE 100 g-1

.

Increasing storage 0 to 30 days showed an increase in phenolic content of peach fruits

from 67.75 to 76.60 mg GAE 100 g-1

. While, a decline in total phenols were observed

(75.09 mg GAE 100g-1

) at 40th

day storage.

The interactive effect of 1-MCP and storage duration on total phenolic contents of

peach fruits was also found significant. The highest total phenolic (80.63 mg GAE

100 g-1

) content was observed in peach fruits stored for 30 days, dipped in 0.9 µg L-1

1-MCP solution. The lowest phenolic content (68.01 mg GAE 100 g-1

) was observed

in freshly harvested peach fruits dipped in 0.3 µg L-1

1-MCP solution (Fig 6.9).

Total Antioxidant activity (mg kg-1

)

The mean Table of 6.3 showed that 1-MCP, storage duration and their interactions

significantly influenced the antioxidant activity of peach.

Regarding the means for 1-MCP concentrations, peach fruits treated with 0.9 µg L-1

1-MCP solution recorded the highest antioxidant activity (65.86 mg kg-1

). The lowest

antioxidant activity (57.23 mg.kg-1

) was noted in peach fruits of control treatment.

For the means of storage duration, more antioxidant activity (66.33 mg kg-1

) was

noted in peach fruits at 30th

day storage which was different from the rest of treatment

followed by antioxidant activity (65.81 mg kg-1

) in peach fruits stored for 30 days.

Minimum antioxidant activity (57.07 mg kg-1

) was observed in peach fruits kept for 0

days.

The interactive effect of 1-MCP concentration and storage duration revealed that more

119


) was recorded in peach fruits treated with 0.9 µg

L-1

1-MCP solution, stored for 30 days. The lowest antioxidant activity (56.03 mg kg-1

)

was recorded in peach fruits kept at 0 day storage of control treatment (Fig 6.10).

Table 6. 3: Free radical scavenging activity (FRSA) (%), catalase activity (U g-1

protein), total phenols (mg GAE 100 g-1

), antioxidant activity (mg kg-1

)

of peach as affected by 1-MCP levels during storage

1-MCP (M)

(µg/L)

Parameters

FRSA

(%)

Catalase activity

(U g-1

protein)

Total Phenols

(mg GAE 100 g-1

)

Antioxidant activity

(mg kg-1

)

0 72.96 c 41.93 b 68.08 d 57.23 d

0.3 74.33 b 42.05 b 73.23 c 63.08 c

0.6 74.48 b 44.68 a 74.82 b 64.82 b

0.9 75.22 a 46.93 b 76.02 a 65.86 a

LSD (P≤ 0.05) 0.25 0.26 0.27 0.25


Control 69.79 e 34.66 d 67.75 e 57.07 e

10 72.59 d 44.84 e 71.66 d 61.76 d

20 74.92 c 46.42 b 74.10 c 63.68 c

30 77.50 a 47.75 a 76.60 a 66.33 a

40 76.43 b 45.81 c 75.09 b 64.88 b

LSD (P≤ 0.05) 0.27 0.29 0.30 0.27


MxSD Fig. 6.7 Fig. 6.8 Fig. 6.9 Fig. 6.10

Significance * ** *** ***


another


respectively.

120


Control 10 20 30 40

Fre

e r

ad

ica

l sca

veng

ing

assa

y (µ

g m

l-1)

68

70

72

74

76

78

80

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6.7: Interactive effect of 1-MCP and storage duration on free radical

scavenging assay (%) of peach


Control 10 20 30 40

Ca

tala

se

activi

ty (

U g

-1 F

W)

36

38

40

42

44

46

48

50

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6.8: Interactive effect of 1-MCP and storage duration on catalase activity (U

g-1

protein) of peach

121


Control 10 20 30 40

To

tal p

he

no

ls (

mg

GA

E 1

00

g-1

FW

)

66

68

70

72

74

76

78

80

82

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6. 9: Interactive effect of 1-MCP and storage duration on total phenols (mg

GAE 100g-1

) of peach


Control 10 20 30 40

Antio

xid

ant a

ctivi

ty (

mg

kg

-1)

54

56

58

60

62

64

66

68

70

72

0 (Control)

0.3 µg/L

0.6 µg/L

0.9 µg/L

Fig 6.10: Interactive effect of 1-MCP and storage duration on antioxidant

activity (mg kg-1

) of peach

122

DISCUSSION

Quality attributes of peach fruits

In the current research, it was observed that 1-MCP treatment had efficiently retained

the quality attributes of peach related to ripening. Results revealed that 1-MCP

application significantly retained firmness, TSS and TSS-acid ratio of peach fruits by

15%, 5% and 12% respectively. Other quality attributes were significantly increased

like TA by 73%, ascorbic acid content by 3% and reducing sugars by 2% of peach

fruits by post harvest treatment of 0.6 µg L-1

1-MCP solution.

This might be due to the fact that 1-MCP being a synthetic cyclic olefin mainly

slowed down ethylene production that lowered down genes related to maturation

action (PC-PG2 and PC-PG1) and other enzymes (Khan and Singh, 2007). The

retention in fruit firmness and decline in TSS might be due to the fact that 1-MCP has

a major role in the controlling softening enzymes of cell wall i.e. endo-PG, exo-PG

and PE, which reduced ehthylene production and respiration rate (Eduardo and Kader,

2007; Win et al., 2006). This process led to less availability of nutrients to the

pathogen which improved the fruit quality (Table 6.1) and reduced disease incidence

(Table 6.2).

Another reason for improvement in the quality attributes of peach with 0.6 µg L-1

1

MCP application in this study might be due to maintenance of intercellular tissue

integrity and adhesiveness (Alonso et al., 1997) that led the fruits to be firmer and

hence improvements in TA, ascorbic acid and sugar contents of the peach fruits

(Table 6.1 and 6.2).

Furthermore, increase in softening due to the loss of firmness in storage might be

attributed to the fact that during storage, the activity of fruit softening enzymes i.e.

endo-PG, exo-PG and PE increased, which made the commodity unhealthy (Kays,

1997) by reducing the amount of TA, ascorbic acid, total sugars and reducing sugars

of apple fruits (Wills et al., 1980). The activity of these enzymes was greatly

controlled by the application of 1-MCP (Eduardo and Kader, 2007).

123

Treating the fruits with 1-MCP positively delayed process of ripening and controlling

the respiration rate (Sigal, 2006) which helped to increase the titratable acidity (TA)

of the fruit compared with untreated fruits. Citric acid and vitamin C mostly shows

the TA in the fruit (Tucker et al., 1993). Furthermore, reduction of TA and sugars

during storage might also be due to loss of sucrose (Itai and Tanahashi, 2008).

Sucrose metabolizing enzymes resulted in better hexoses (sugar) accumulation, which

led the accumulation and retention of all the quality attributes.

Another reason for improvement of ascorbic acid might be due to the fact that

application of 1-MCP reduces the gene expression of ascorbate peroxidase (A major

oxidative enzyme of ascorbic acid) (Ma et al., 2010) hence retained the ascorbic acid

in peach. The decline in biochemical attributes (TSS, vitamin C and TA) might also

be due to action of ethylene inhibitors which limit metabolism of fruit respiration and

fungal growth (Hagenmaier, 2005).

1-MCP slowed vitamin C loss in peaches (Liu et al., 2005) and pineapples (Selvarajah

et al., 2001) which greatly confirmed the present results. Unlike our data, Asrey et al.

(2012) reported that 1-MCP showed a non significant response to quality attributes of

kinnow mandarin. The effectiveness of 1-MCP has been proven in many researches

done on apple (Mir et al., 2001; Yuan and Carbaugh, 2007) and peaches (Hayama et

al., 2008) greatly confirmed the present results. They reported that the qualitative

attributes of the above mentioned crops were significantly improved by the

application of 1-MCP. Qiuping and Wenshui (2007) reported that 1-MCP in

combination with Chitosan better retained all the quality attributes (firmness, TSS,

TA, TSS-acid ratio, sugars, ascorbic acid and weightloss) in China fruit. Furthermore,

ascorbic acid content of mango was retained by treating the fruits with 1-MCP as

compared to control (Sivakumar et al., 2012). Moreover, the present results are also in

close conformity with those reported by Fan et al. (1999) in apple and Golding et al.

(1999) and Jiang et al. (2004a) in banana. In another study, increase in firmness, TA,

reduced TSS and TSS-acid ratio of plum fruits was observed by the application of

124

1-MCP treated fruits (Khan and Singh, 2008). DeLong et al. (2004) and Fan et al.

(1999) recorded 1-MCP retained acidity in apples stored in low temperature air.

Weight loss and Disease incidence

Disease resistance and reduction in weight loss is generally related to degree of

ripeness. In the present study, disease incidence and weight loss was minimized by 8

and 6% respectively, due to the delay in ripening process as a result of 1-MCP

treatment.

The reason for the increase in disease resistance might be attributed to the enhanced

activity of certain enzymes like PAL (phenylalanine ammonia-lyase), PPO

(polyphenol oxidase) and POD (peroxidase) etc (Chappell et al., 1984). Increased

PAL activity is closely linked with synthesis of toxic metabolites such as

phytoalexins, phenols and lignins in the defense pathway of the plant. It is well

understood from previous studies that the synthesis of these toxic metabolites are

enhanced by the application of 1-MCP (Chappell et al., 1984). The increase in weight

loss and disease incidence during storage might be due to softening of peach fruits

during storage. Softening of fruits involve series of changes in the polysaccharide of

middle lamella and primary cell wall (Fischer and Bennett, 1991).

Another reason of softening could be the hydrolysis of polysaccharides and

modification in the polymers bonds established with turgor alterations, which resulted

in increased cell separation and softening of the cell wall (Brummell, 2006).

Furthermore, the enhanced cell wall degrading enzymes such as endo-1,4-β-glucanase

(EGase), exo polygalacturonase (exo-PG), endo-polygalacturonase and pectin esterase

(PE) resulted in softening of fruits hence increase the ripening process of peach

(Brummell et al., 2004; Ullah et al., 2013) which increased the rate of respiration and

results in the weight loss of fruit that let the door open for attack of pathogens and

micro organism. Application of 1-MCP significantly retained weight loss and

minimized the attack of disease (Table 6.1 and 6.2), which is a clear indication that

125

1-MCP had a major role in controlling biochemical changes occurring in the fruit (Liu

et al., 2005).

In peaches, depolymerization of glycan matrix (which is tightly and loosely associated

with cellulose) and galacturonic acid loss from cell wall results in softening of fruit

cell wall (Ortiz et al., 2011), which were effectively controlled by the application of

1-MCP (Hayama et al., 2008). The reduction in the rate of respiration due to the

application of 1-MCP could be the reason that contributed to the reduction of weight

loss (Liu et al., 2005), but it is largely linked with exposure time in peaches (Hayama

et al., 2005).

Another reason for the reduction of weight loss and disease attack might be due to the

fact that 1-MCP increased in fruit firmness (Eduardo and Kader, 2007) that prevented

the invasion of micro organism and pathogens in the stored fruits, which greatly

confirmed the present results as well. Integritiy of fruit peel and decreased

evaporation, nutrient loss and gas exchange is due to the application of 1-MCP

(Tavallali and Moghadam, 2015; Amarante et al., 2001).

The current results are in close relation with those quoted by Aguayo (2006) who

recorded a decrease in disease incidence and weight loss of strawberry fruits by

combine application of CaCl2 + 1-MCP. Furthermore, Valero et al. (2003) concluded

that fruit weight loss was delayed with 1-MCP treated plum fruits. However,

contradictory findings of Fan and Mattheis (2000) stated that there was no or limited

effect of 1-MCP application on apricot fruit weight loss.

Total phenols, Free radical scavenging assay (FRSA), catalase activity, Total

antioxidant activity

In the present study, increase in 1-MCP concentration from control to 0.9 µg L-1

gradually increased the FRSA from 2 to 3% of peach fruits (Table 6.3). Fruit

antioxidants are thought to protect the tissues against any stress or diseases.

Resistance against post harvest diseases are induced by the specific antifungal

126

molecules such as phenolic compounds. These compounds may act to enhance the

quality as well as extend the post harvest life of the commodity (Hebert et al., 2002).

The antioxidant activity influenced the vitimans and several polyphenolic compounds

in fruits results in high free radical scavenging activity (FRSA) (Akhtar, 2010). The

post harvest storage life is determined by antioxidant activity that are concerned with

some physical and chemical attributes like peel color and flesh firmness (Dalla et al.,

2007). Post harvest life of fruits greatly depends on the antioxidant activity of fruits

(Di Vaio et al., 2008). Furthermore, in the same study, they also reported that

antioxidant content of peach fruits greatly varied with the time of harvest, storage

techniques and time between picking and consumption. Furthermore, balance of free

radicals is also with the help of treating fruits with 1-MCP concentrations. Similar

results were also recorded in melons (Oms-Oliu et al., 2008).

Oxidative enzymes i.e. Reactive oxygen specie, especially hydrogen peroxide is

involved in quality deteroation of fruits, is greatly controlled by the activity of

antioxidative enzymes particularly catalase. In the present study, highest catalase

activity (12%), Total phenols (12%) and antioxidant activity (15%) in peach fruits

was recorded with 0.9 µg L-1

1MCP application as compared to control and the rest of

1-MCP treatments. Increased catalase activity, phenolic compounds and antioxidant

activity are key defensive actions against damages caused by oxidation process, while

decreased activity of catalase enzymes weakens the ability of the cells to synthisize

hydrogen peroxide (Ji et al., 1988).

Fruit senescence positively correlates with antioxidant enzymes (Lemoine, 2010). To

overcome the oxidative damage of fruits during storage, plants had developed a

system of antioxidants system which contains enzymatic and non enzymatic

onstituents that delayed the process of senescence (Lemoine, 2010). This system is

further strengthened by post harvest application of certain chemicals like calcium

(Sharma et al., 1996) and 1-MCP (Tavallali and Moghadam, 2015) etc. synthesis of

antioxidants in defence of free radicals and stress during cold storage greatly

127

contributes to decreased antioxidant activity during storage (Gulen and Eris, 2004). In

the present research, total antioxidant activity (7%) and phenols (13%) declined

during storage. This might be due to the fact that the breakdown of toxic metabolites

caused all the activity to slow down and other injuries caused by oxygen stress

(Kaynara et al., 2005), hence leading to the softening of fruits and ultimately resulted

in reduced post harvest quality. All these processes were effectively controlled by the

application of 1-MCP (Ozkan et al., 2012).

Flavor and color is determined by phenolic content present in the fruit. Phenolics are

secondary metabolites which are synthesized by all the plants (Jeong et al., 2008).

Phenolics are involved in several plant functions like photosynthesis, nutrient

absorption in plants, synthesis of protein and enzymatic activities (Robbins, 2003).

1-MCP, being a recent technology, has the ability to be used as a commercial

technology due to its ability to up held the capability of antioxidant capacity, hence

delaying the ripening process (Ilic et al., 2013).

The present findings are in close conformity with results obtained by Tavarini et al.

(2007) for kiwi fruit, Policegoudra and Aradhya (2007) for and Cordenusi et al. (2003)

for strawberry. Moreover, minumum Vitamin C, flavoniods and activities of

antioxidant were observed in orange and grapefruit during storage (Gardner et al.,

2000) while activities of antioxidant increased by the application of 1-MCP as

reported by Asrey et al. (2012).

128


Summary

To increase the shelf life and storability of peach, an experiment entitled “influence of

1-Methylcyclopropene (1-MCP) concentrations on the storability of Peach cv. Early

Grand” was undertaken in Post harvest, laboratory, Horticulture and Agriculture

Chemistry department, UAP, Peshawar during 2015. Fruits were properly placed

according to CR Design repeated three times. Fruits were then dipped in different

concentration of 1MCP (0, 0.3, 0.6 and 0.9 µg L-1

) and stored for 40 days with 10

days interval under low temperature (8+2 C with 50% RH).

Different biochemical attributes i.e percent weight loss (%), fruit firmness (kg.cm-2

),

TSS (°brix), percent acidity (%), TSS-acid ratio, vitamin C (mg.100g-1

), reducing and

non reducing sugar (%), fruit decay (%), DPPH free radical scavenging assay (%),

catalase activity (U g-1

protein), total phenolics content (mg GAE 100g-1

) and

anitoxidant activity (mg kg-1

) of the peach fruits were studied during the course of the

experiment. Some of the major findings are given as under.

The experimental results showed that 1MCP significantly affected all the studied

attributes. The lowest weight loss (5.55%), fruit decay (6.95%), total soluble content

(8.79 °brix), TSS to acid ratio (12.15), more firmness of fruits (5.61 kg cm-2

), TA

(0.73%). Vitamin C (6.19 mg.100g-1

), reducing sugars (1.79%) were measured in

fruits dipped in 0.6 µg L-1

1MCP. While, free radical scavenging assay (75.22 %),



) and


) was recorded in fruits treated with 0.9 µg L-1

1MCP solution while the lowest non reducing sugars (3.97%) were observed when

fruits were treated with 0.3 µg L-1

1MCP solution. The highest weightloss (16.01%),

fruit decay (17.41), TSS (9.28 °brix), TSS to acid ratio (13.78), non reducing sugar

(4.04%), minimum firmness of fruits (4.89 kg.cm-2

), TA (0.68%). Vitamin C (6.03

mg.100g-1

), reducing sugars (1.72%), free radical scavenging assay (72.96 %),



) and

129


) were recorded in untreated fruits with 1-MCP.

The lowest weight loss (4.27), fruit decay (6.27%), total soluble content (8.45 °brix),

TSS to acid ratio (11.15), highest fruit firmness (5.83 kg cm-2

), acidity (0.76%), total

sugars (5.83%) were observed when fruits were harvested as fresh. Freshly harvested

fruits showed the highest vitamin C (6.25 mg 100g-1

), non reducing sugars (4.17%),

lowest reducing sugars (1.40%), free radical scavenging assay (69.79 %), catalase

activity (34.66 U g-1


) and antioxidant

activity (57.07 mg kg-1

). While the highest weight loss (10.19%), fruit decay (11.69%),

total soluble content (9.28 °brix), TSS to acid ratio (15.89), reducing sugars (2.16%),

free radical scavenging assay (69.79 %), minimum firmness of fruits (4.28 kg.cm-2

),

percent acidity (0.63%), Vitamin C (5.88 mg.100g-1

), non reducing sugars (3.86%)

were observed when fruits were stored for 40 days. Highest catalase activity (47.75 U

g-1


) and antioxidant activity (66.33 mg

kg-1

) were found in 30 days of storage.

The interactive effect of 1MCP (M) and storage duration (SD) revealed that M×SD

significantly affected all the studied attributes of peach fruits except TSS, percent

acidity and TSS-acid ratio.

Conclusions

The following conclusions are deduced from the present results

Peach fruits treated with 0.6 µg L-1

1MCP solution significantly retained all

the quality attributes of peach fruits up to 40 days

However, higher free radical scavenging assay, catalase activity, antioxidant

activity, total phenols and lower weight loss and fruit decay were observed in

peach fruits treated with 0.9 µg L-1

1-MCP up to 30 days

A gradual increase in free radical scavenging assay, catalase activity, total

phenols and antioxidant activity were observed by the application of 1-MCP at

0.9 µg L-1

up to 30 days and a decline was observed onwards

130

Recommendations

Based on the conclusions, it is recommended that

The peach fruit could be treated 0.6 µg L-1

1MCP solution to retain most of the

quality attributes during storage at 8±2 0C temperature with 50% RH

In order to retain the activities of free radical scavenging assay, catalase

activity, total phenols and antioxidant activity, the peach fruit could be treated

with 0.9 µg L-1

1-MCP solution stored at 8±2 0C temperature with 50% RH

131

OVER ALL CONCLUSIONS AND RECOMMENDATIONS

Over all conclusion

Peach fruit trees thinned at 40% after 14 days of fruit set showed better

response to the studied attributes of peach trees

Lower fruit yield and higher split pits of peach was recorded in trees thinned at

60% fruit thinning thinned after 7 days of fruit set

Irrigation interval of 10 days to peach trees and foliar application of GA3 at

100 ppm significantly increased fruit weight, fruit volume, fruit yield but

reduced the number of fruit kg-1

and split pit incidence of peach

Foliar application of calcium chloride at 1% significantly retained some of the

biochemical attributes of peach fruit up to 30 days but showed a non

significant response to ascorbic acid content, percent acidity, reducing and non

reducing sugars

Fruits treated with 0.6 µg L-1

significantly retained the biochemical attributes

of peach fruits up to 40 days of storage. However, higher free radical

scavenging assay, catalase activity, total phenols and antioxidant activity,

lower weight loss and fruit decay was observed in fruits treated with 0.9 µg L-1

1-MCP

Over all Recommendations

The following recommendations are made on the basis of the conclusions

Peach fruit trees thinned 14 days after fruit set with 40% fruit thinning could

be recommended to produce better fruit yield and other quality attributes of

peach cv. Early Grand

Irrigation interval of 10 days and foliar application of GA3 at 100 ppm is

recommended to minimize the split pit incidence without affecting the fruit

growth and yield of peach fruit trees

Peach trees cv. Early Grand could be foliar sprayed with 1.0% CaCl2 to retain

the maximum quality attributes during storage up to 30 days at Temp 8±2 0C

with RH 50%

132

The peach fruits could be treated with 0.6 µg L-1

1MCP solution to retain most

of the quality attributes during storage at 8±2 0C temperature with 50% RH

In order to retain the activities of free radical scavenging assay, catalase

activity, total phenols and antioxidant activity, the peach fruits could be

treated with 0.9 µg L-1

1MCP solution.

Future research is suggested to study the effect of thinning in other cultivars of

peach. Various other chemicals or nutrients needs to be investigated to reduce

the problems of split pits and other physiological disorders. Moreover other

chemicals both pre and post harvest, could also be studied for further increase

in shelf life of peach fruits.

133

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179

APPENDICES

Anova Tables for all the experiments

Table 3.1a: Analysis of variance for fruit weight (g) of peach fruits as affected by

thinning intensity and time.

SOV DF SS MS Fcal Prob Sig

Rep 2 31.62 15.81

Thinning 2 1638.22 819.11 65.76 0.000 ***

Time 2 1184.06 592.03 47.53 0.000 ***

ThxTi 4 159.22 39.81 3.20 0.038 *

Control vs Rest 1 8101.63 8101.63 650.40 0.000 ***

Error 18 224.22 12.46

Total 29 11338.97

Table 3.2a: Analysis of variance for fruit volume (cm3) of peach fruits as affected

by thinning intensity and time.


Rep 2 34.62 17.31

Thinning 2 3009.69 1504.84 168.02 0.000 ***

Time 2 304.52 152.26 17.00 0.000 ***

ThxTi 4 87.48 21.87 2.44 0.084 Ns

Control vs Rest 1 4021.35 4021.35 448.99 0.000 ***

Error 18 161.22 8.96

Total 29 7618.87

Table 3.3a: Analysis of variance for number of fruits kg-1

of peach fruits as

affected by thinning intensity and time.


Rep 2 0.10 0.05

Thinning 2 9.34 4.67 42.25 0.000 ***

Time 2 4.77 2.39 21.60 0.000 ***

ThxTi 4 0.55 0.14 1.24 0.328 Ns

Control vs Rest 1 117.50 117.50 1062.92 0.000 ***

Error 18 1.99 0.11

Total 29 134.25

180

Table 3.4a: Analysis of variance for fruits yield tree-1

(kg) of peach fruits as

affected by thinning intensity and time.


Rep 2 106.62 53.31

Thinning 2 89.02 44.51 9.57 0.001 **

Time 2 175.72 87.86 18.89 0.000 ***

ThxTi 4 17.89 4.47 0.96 0.452 ns

Control vs Rest 1 57.27 57.27 12.31 0.003 **

Error 18 83.72 4.65

Total 29 530.24

Table 3.5a: Analysis of variance for fruit firmness (kg cm-2




Rep 2 0.00 0.00

Thinning 2 0.61 0.30 176.65 0.000 ***

Time 2 0.41 0.21 120.04 0.000 ***

ThxTi 4 0.08 0.02 11.39 0.000 ***

Control vs Rest 1 0.95 0.95 553.98 0.000 ***

Error 18 0.03 0.00

Total 29 2.09

Table 3.6a: Analysis of variance for total soluble solids (°brix) of peach as

affected by thinning intensity and time


Rep 2 0.00 0.00

Thinning 2 7.24 3.62 618.81 0.000 ***

Time 2 0.50 0.25 42.97 0.000 ***

ThxTi 4 0.13 0.10 1.66 0.404 NS

Control vs Rest 1 7.92 7.92 1353.84 0.000 ***

Error 18 0.11 0.01

Total 29 15.91

181

Table 3.7a: Analysis of variance for percent acidity (%) of peach as affected by



Rep 2 0.00 0.00

Thinning 2 0.10 0.05 71.76 0.000 ***

Time 2 0.03 0.01 18.02 0.000 ***

ThxTi 4 0.00 0.00 0.04 0.997 Ns

Control vs Rest 1 0.01 0.01 14.12 0.001 **

Error 18 0.01 0.00

Total 29 0.15

Table 3.8a: Analysis of variance for TSS-Acid ratio of peach as affected by



Rep 2 29.87 14.93 3.36

Thinning 2 68.96 34.48 7.76 0.004 **

Time 2 40.69 20.34 4.58 0.025 *

ThxTi 4 1.93 0.48 0.11 0.978 Ns

Control vs Rest 1 1.96 1.96 0.44 0.515 Ns

Error 18 79.97 4.44

Total 29 223.37

Table 3.9a: Analysis of variance for ascorbic acid (mg 100g-1




Rep 2 0.02 0.01 0.79

Thinning 2 1.86 0.93 59.71 0.000 ***

Time 2 1.44 0.72 46.14 0.000 ***

ThxTi 4 0.35 0.09 5.64 0.004 **

Control vs Rest 1 0.44 0.44 28.51 0.000 ***

Error 18 0.28 0.02

Total 29 4.40

182

Table 3.10a: Analysis of variance for split pits incidence (%) of peach as affected



Rep 2 4.02 2.01 1.99

Thinning 2 223.63 111.81 110.89 0.000 ***

Time 2 102.74 51.37 50.95 0.000 ***

ThxTi 4 20.09 5.02 4.98 0.007 **

Control vs Rest 1 59.74 59.74 59.24 0.000 ***

Error 18 18.15 1.01

Total 29 428.37

183

Chapter 4

Table 4.1a: Analysis of variance for leaf area (cm2) of peach as affected by

irrigation intervals and gibbrellic acid concentrations


Rep 2 0.042 0.021 0.008 0.992 Ns

Irrigation 2 115.125 57.563 22.835 0.006 **

Error I 4 10.083 2.521

GA 3 5.910 1.970 1.740 0.195 Ns

SxG 6 1.153 0.192 0.170 0.982 Ns

Error II 18 20.375 1.132

Total 35 152.688

Table 4.2a: Analysis of variance for fruit weight (g) of peach as affected by



Rep 2 15.72 7.86 9.13 0.03 *

Irrigation 2 254.89 127.44 148.00 0.00 ***

Error I 4 3.44 0.86

GA 3 188.89 62.96 17.66 0.00 ***

SxG 6 22.44 3.74 1.05 0.43 ns

Error II 18 64.17 3.56

Total 35 549.56

Table 4.3a: Analysis of variance for fruit volume (cm3) of peach as affected by



Rep 2 4.667 2.333 5.600 0.069 Ns

Irrigation 2 93.167 46.583 111.800 0.000 ***

Error I 4 1.667 0.417

GA 3 195.639 65.213 85.890 0.000 ***

SxG 6 9.944 1.657 2.183 0.093 Ns

Error II 18 13.667 0.759

Total 35 318.750

184

Table 4.4a: Analysis of variance for number of fruits kg-1

of peach as affected by



Rep 2 0.667 0.333 8.000 0.140 Ns

Irrigation 2 18.667 9.333 224.000 0.000 ***

Error I 4 0.167 0.042

GA 3 20.972 6.991 27.963 0.000 ***

SxG 6 1.778 0.296 1.185 0.358 Ns

Error II 18 4.500 0.250

Total 35 46.750

Table 4.5a: Analysis of variance for fruit yield (kg) of peach as affected by



Rep 2 0.014 0.007 0.005 0.995 Ns

Irrigation 2 66.681 33.340 22.435 0.007 **

Error I 4 5.944 1.486

GA 3 69.743 23.248 35.239 0.000 ***

SxG 6 7.819 1.303 1.975 0.123 Ns

Error II 18 11.875 0.660

Total 35 162.076

Table 4.6a: Analysis of variance for split pit incidence (%) of peach as affected by



Rep 2 2.056 1.028 1.254 0.378 Ns

Irrigation 2 499.056 249.528 304.508 0.000 ***

Error I 4 3.278 0.819

GA 3 158.688 52.896 62.095 0.000 ***

SxG 6 9.167 1.528 1.793 0.157 Ns

Error II 18 15.333 0.852

Total 35 687.576

185

Table 4.7a: Analysis of variance for total soluble solids (0brix) of peach as

affected by irrigation intervals and gibbrellic acid concentrations


Rep 2 0.114 0.057 10.111 0.127 Ns

Irrigation 2 11.611 5.806 1032.111 0.000 ***

Error I 4 0.022 0.006

GA 3 24.222 8.074 79.038 0.000 ***

SxG 6 0.214 0.036 0.349 0.901 ns

Error II 18 1.839 0.102

Total 35 38.022

Table 4.8a: Analysis of variance for fruit firmness (kg cm-2


by irrigation intervals and gibbrellic acid concentrations


Rep 2 0.121 0.060 5.425 0.073 Ns

Irrigation 2 2.187 1.094 98.425 0.000 ***

Error I 4 0.044 0.011

GA 3 0.657 0.219 16.768 0.000 ***

SxG 6 0.028 0.005 0.362 0.894 Ns

Error II 18 0.235 0.013

Total 35 3.272

186

Chapter 5

Table 5.1a: Analysis of variance for fruit firmness (kg cm2) of peach as affected

by calcium sources, concentration during storage

SOV DF SS MS Fcal Prob

Rep 2 0.040 0.020 0.171 0.843

Ca-Source (S) 2 2.057 1.029 8.820 0.000

Ca-Concentration (C) 2 5.116 2.558 21.930 0.000

SxC 4 1.236 0.309 2.648 0.039

Control vs Rest 1 1.267 1.267 10.862 0.001

Storage (St) 3 8.658 2.886 24.742 0.000

SxSt 6 0.437 0.073 0.624 0.711

CxSt 6 4.808 0.801 6.870 0.000

SxCxSt 12 6.266 0.122 0.977 0.500

CRxSt 3 0.330 0.110 0.942 0.424

Error 81 9.448 0.117

Total 119 31.003

Table 5.2a: Analysis of variance for total soluble solids (°Brix) of peach as

affected by calcium sources and concentration during storage


Rep 2 0.017 0.009 0.026 0.975

Source 2 11.787 5.894 17.515 0.000

Concentration 2 29.982 14.991 44.550 0.000

SxC 4 6.898 1.725 5.125 0.001

Control vs Rest 1 1.841 1.841 5.471 0.022

Storage 3 26.376 8.792 26.128 0.000

SxSt 6 3.197 0.533 1.584 0.163

CxSt 6 2.554 0.426 1.265 0.283

SxCxSt 12 1.556 0.130 0.385 0.965

CRxSt 3 0.138 0.046 0.136 0.938

Error 81 27.256 0.336

Total 119 85.226

187

Table 5.3a: Analysis of variance for percent acidity (%) of peach as affected by

calcium sources and concentration during storage


Rep 2 0.007 0.003 0.838 0.436

Source 2 0.007 0.004 0.897 0.412

Concentration 2 0.005 0.002 0.588 0.558

SxC 4 0.031 0.008 1.904 0.118

Control vs Rest 1 0.013 0.013 3.218 0.077

Storage 3 0.253 0.084 20.364 0.000

SxSt 6 0.018 0.003 0.724 0.631

CxSt 6 0.052 0.009 2.090 0.063

SxCxSt 12 0.059 0.005 1.187 0.306

CRxSt 3 0.001 0.000 0.069 0.976

Error 81 0.335 0.004

Total 119 0.528

Table 5.4a: Analysis of variance for TSS-acid ratio for peach as affected by



Rep 2 2.263 1.132 0.293 0.747

Source 2 25.340 12.670 3.281 0.043

Concentration 2 155.422 77.711 20.126 0.000

SxC 4 2.581 0.645 0.167 0.955

Control vs Rest 1 1.479 1.479 0.383 0.538

Storage 3 286.330 95.443 24.718 0.000

SxSt 6 9.027 1.504 0.390 0.884

CxSt 6 12.857 2.143 0.555 0.765

SxCxSt 12 5.157 0.430 0.111 1.000

CRxSt 3 1.551 0.517 0.134 0.940

Error 81 312.766 3.861

Total 119 528.443

188

Table 5.5a: Analysis of variance for ascorbic acid (mg 100g-1


by calcium sources and concentration during storage


Rep 2 0.279 0.140 0.896 0.412

Source 2 0.027 0.013 0.085 0.919

Concentration 2 0.139 0.069 0.445 0.642

SxC 4 0.804 0.201 1.290 0.281

Control vs Rest 1 0.366 0.366 2.348 0.129

Storage 3 3.636 1.212 7.776 0.000

SxSt 6 1.332 0.222 1.425 0.215

CxSt 6 1.919 0.320 2.052 0.068

SxCxSt 12 2.026 0.169 1.083 0.385

CRxSt 3 0.400 0.133 0.855 0.468

Error 81 12.625 0.156

Total 119 19.917

Table 5.6a: Analysis of variance for reducing sugars (%) of peach as affected by



Rep 2 0.006 0.003 0.016 0.984

Source 2 0.044 0.022 0.110 0.896

Concentration 2 0.470 0.235 1.181 0.312

SxC 4 1.569 0.392 1.971 0.107

Control vs Rest 1 0.012 0.012 0.061 0.806

Storage 3 16.083 5.361 26.940 0.000

SxSt 6 0.280 0.047 0.234 0.964

CxSt 6 0.248 0.041 0.208 0.973

SxCxSt 12 0.131 0.011 0.055 1.000

CRxSt 3 0.189 0.063 0.317 0.813

Error 81 16.119 0.199

Total 119 19.068

189

Table 5.7a: Analysis of variance for non reducing sugars (%) of peach as affected



Rep 2 0.004 0.002 0.097 0.907

Source 2 0.014 0.007 0.303 0.740

Concentration 2 0.017 0.009 0.373 0.690

SxC 4 0.081 0.020 0.885 0.477

Control vs Rest 1 0.013 0.013 0.552 0.460

Storage 3 1.791 0.597 26.151 0.000

SxSt 6 0.078 0.013 0.568 0.754

CxSt 6 0.112 0.019 0.817 0.560

SxCxSt 12 0.030 0.002 0.108 1.000

CRxSt 3 0.058 0.019 0.852 0.470

Error 81 1.849 0.023

Total 119 2.255

Table 5.8a: Analysis of variance for brown rot incidence (%) of peach as affected



Rep 2 0.201 0.101 0.003 0.997

Source 2 346.878 173.439 5.997 0.004

Concentration 2 551.281 275.640 9.530 0.000

SxC 4 302.908 75.727 2.618 0.041

Control vs Rest 1 177.463 177.463 6.136 0.015

Storage 3 2328.158 776.053 26.832 0.000

SxSt 6 120.050 20.008 0.692 0.657

CxSt 6 205.197 34.200 1.182 0.324

SxCxSt 12 119.704 9.975 0.345 0.978

CRxSt 3 82.186 27.395 0.947 0.422

Error 81 2342.764 28.923

Total 119 4248.633

190

Table 5.9a: Analysis of variance for weight loss (%) of peach as affected by



Rep 2 0.370 0.185 0.006 0.994

Source 2 242.107 121.053 3.843 0.025

Concentration 2 243.398 121.699 3.864 0.025

SxC 4 348.231 87.058 2.764 0.033

Control vs Rest 1 14.901 14.901 0.473 0.494

Storage 3 2533.433 844.478 26.810 0.000

SxSt 6 105.241 17.540 0.557 0.763

CxSt 6 131.370 21.895 0.695 0.654

SxCxSt 12 150.868 12.572 0.399 0.960

CRxSt 3 26.280 8.760 0.278 0.841

Error 81 2551.373 31.498

Total 119 3814.139

Table 5.10a: Analysis of variance for fruit calcium content (%) of peach as



Rep 2 0.233 0.116 1.916 0.154

Source 2 67.586 33.793 556.329 0.000

Concentration 2 23.878 11.939 196.548 0.000

SxC 4 1.399 0.350 5.758 0.000

Control vs Rest 1 2.454 2.454 40.398 0.000

Storage 3 0.373 0.124 2.048 0.114

SxSt 6 0.688 0.115 1.889 0.093

CxSt 6 0.664 0.111 1.823 0.105

SxCxSt 12 0.885 0.074 1.215 0.288

CRxSt 3 0.246 0.082 1.350 0.264

Error 81 4.920 0.061

Total 119 102.953

191

Table 5.11a: Analysis of variance for ion leakage from cell membrane (%) of

peach as affected by calcium sources and concentration during

storage


Rep 2 1.033 0.517 0.014 0.986

Source 2 896.352 448.176 12.110 0.000

Concentration 2 919.019 459.509 12.416 0.000

SxC 4 16.204 4.051 0.109 0.979

Control vs Rest 1 748.334 748.334 20.220 0.000

Storage 3 2914.292 971.431 26.248 0.000

SxSt 6 60.611 10.102 0.273 0.948

CxSt 6 94.611 15.769 0.426 0.860

SxCxSt 12 94.389 7.866 0.213 0.997

CRxSt 3 549.847 183.282 4.952 0.003

Error 81 2997.785 37.010

Total 119 6378.184

Table 5.12a: Analysis of variance for ion leakage from cell wall (%) of peach as



Rep 2 10.288 5.144 0.430 0.652

Source 2 356.060 178.030 14.884 0.000

Concentration 2 290.727 145.363 12.153 0.000

SxC 4 109.537 27.384 2.289 0.067

Control vs Rest 1 53.111 53.111 4.440 0.038

Storage 3 819.623 273.208 22.842 0.000

SxSt 6 29.958 4.993 0.417 0.865

CxSt 6 6.236 1.039 0.087 0.997

SxCxSt 12 24.500 2.042 0.171 0.999

CRxSt 3 0.578 0.193 0.016 0.997

Error 81 968.826 11.961

Total 119 1849.822

192

Chapter 6

Table 6.1a. Analysis of variance for weight loss (%) of peach as affected by

1MCP concentrations and storage durations.


MCP 3 1.76 0.59 48.12 0.00 ***

Storage 4 738.01 184.50 15164.68 0.00 ***

MxS 12 0.84 0.07 5.78 0.00 ***

Error 40 0.49 0.01

Total 59 741.10

Table 6.2a: Analysis of variance of fruit firmness (kg cm-2

) of peach fruits as

affected with 1MCP and storage durations.


MCP 3 4.02 1.34 146.18 0.000 ***

Storage 4 17.28 4.32 471.34 0.000 ***

MxS 12 0.25 0.02 2.26 0.027 *

Error 40 0.37 0.01

Total 59 21.92

Table 6.3a: Analysis of variance of total soluble solids (0brix) of peach as affected

by 1MCP levels and storage durations


MCP 3 1.90 0.63 64.80 0.000 ***

Storage 4 17.83 4.46 457.23 0.000 ***

MxS 12 0.15 0.01 1.26 0.279 Ns

Error 40 0.39 0.01

Total 59 20.26

193

Table 6.4a: Analysis of variance for percent acidity (%) of peach fruits as

affected by 1MCP and storage durations


MCP 3 0.03 0.01 35.88 0.000 ***

Storage 4 0.12 0.03 123.43 0.000 ***

MxS 12 0.00 0.00 0.96 0.500 Ns

Error 40 0.01 0.00

Total 59 0.16

Table 6.5a: Analysis of variance for TSS-Acid ratio of peach as affected by 1MCP

levels and storage durations.


MCP 3 20.72 6.91 97.60 0.000 ***

Storage 4 166.09 41.52 586.71 0.000 ***

MxS 12 1.79 0.15 2.11 0.039 *

Error 40 2.83 0.07

Total 59 191.44

Table 6.6a: Analysis of variance of ascorbic acid content (mg/100 g) of peach as

affected by 1MCP levels and storage durations


MCP 3 0.19 0.06 55.16 0.00 ***

Storage 4 1.03 0.26 222.75 0.00 ***

MxS 12 0.05 0.00 3.90 0.00 ***

Error 40 0.05 0.00

Total 59 1.32

194

Table 6.7a: Analysis of variance for reducing sugars (%) of peach as affected by

1MCP levels and storage durations


MCP 3 0.04 0.01 20.01 0.000 ***

Storage 4 4.07 1.02 1635.90 0.000 ***

MxS 12 0.02 0.00 2.16 0.035 *

Error 40 0.02 0.00

Total 59 4.15

Table 6.8a: Analysis of variance for non reducing sugars (%) of peach as affected

by 1MCP levels and storage durations


MCP 3 0.02 0.01 15.04 0.000 ***

Storage 4 0.64 0.16 370.54 0.000 ***

MxS 12 0.03 0.00 6.21 0.000 ***

Error 40 0.02 0.00

Total 59 0.71

Table 6.9: Analysis of variance for fruit decay (%) of peach as affected by

1MCP levels and storage durations


MCP 3 1.76 0.59 48.12 0.00 ***

Storage 4 953.37 238.34 19589.88 0.00 ***

MxS 12 0.84 0.07 5.78 0.00 ***

Error 40 0.49 0.01

Total 59 956.46

195

Table 6.10a: Analysis of variance for free radical scavenging activity (%) of

peach as affected by 1MCP levels and storage durations


MCP 3 7.97 2.66 23.95 0.000 ***

Storage 4 459.34 114.84 1035.32 0.000 ***

MxS 12 3.46 0.29 2.60 0.012 *

Error 40 4.44 0.11

Total 59 475.21

Table 6.11a: Analysis of variance for catalase activity (U g-1

FW) of peach as



MCP 3 7.42 2.47 20.06 0.000 ***

Storage 4 1000.08 250.02 2027.84 0.000 ***

MxS 12 4.17 0.35 2.82 0.007 **

Error 40 4.93 0.12

Total 59 1016.60

Table 6.12a: Analysis of variance for total phenolic content (mg GAE 100 g-1

) of

peach as affected by 1MCP levels and storage durations


MCP 3 7.02 2.34 21.12 0.000 ***

Storage 4 941.65 235.41 2124.79 0.000 ***

MxS 12 5.81 0.48 4.37 0.000 ***

Error 40 4.43 0.11

Total 59 958.91

196

Table 6.13a: Analysis of variance for antioxidant activity (mg kg-1

) of peach as



MCP 3 7.02 2.34 21.12 0.000 ***

Storage 4 925.16 231.29 2087.57 0.000 ***

MxS 12 5.81 0.48 4.37 0.000 ***

Error 40 4.43 0.11

Total 59 942.42

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