chapter 2 fruit maturity indices and...

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CHAPTER 2

FRUIT MATURITY INDICES AND INFLUENCE OF SEASON

2.1 EFFECT OF FRUIT MATURITY INDICES ON SEED OIL AND

GERMINATION

2.1.1 Introduction

Quality issues of fruits or seeds are closely associated with their maturity

stages during collection. Maturity stage is known to affect the viability, storability and

fruit or seed constituents in many cases. Maturity indices vary according to fruit type and

species. The most commonly used indices of fruit or seed maturity are based on physical

properties. Change of fruit colour is widely used as a maturity index in both dry and

fleshy fruits. Generally, the most common colour changes are from a “vegetative green”

to a shade of brown in dry fruits or to a bright or blue-black color in fleshy fruits (Willan,

1985). In Jatropha, usually black dry fruits are collected for oil by the farmers and the

fruit colour change is not given importance. The superiority of quantity and quality of the

oil obtained from the black dry fruit over other yellow and black pulpy maturity stages of

Jatropha curcas has not been examined. Hence an experiment was designed to test this

and to determine the appropriate fruit maturity stage for obtaining high oil yield with

good quality.

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Yellow Black pulpy Black dry

Plate 5. Fruits collected at different maturity stages

Plate 6. Soxhlet apparatus for oil content estimation Plate 7. Oil extracted using

soxhlet apparatus


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2.1.2 Materials and Methods

2.1.2.1 Seed collection and processing

Fruits of Jatropha curcas were collected from 20 trees each in 4 different

locations viz. L1- Attapady (11° 14’ N ; 76° 48’ E), L2- Coimbatore (11° N; 77° E), L3-

Palani (10° 26’ N; 77° 30’ E), and L4- Sathyamangalam (11° 30’N; 77° 17’E). The bulk

of each source was separated into three different sub lots based on the fruit

pericarp colour namely yellow (deep yellow) (8 weeks following anthesis), black

pulpy (10 weeks following anthesis) and black dry (after 12 weeks following anthesis)

which is considered in the present study as an indicator of maturity stage (Figure 1 and

Plate 5). The yellow and black pulpy fruits were processed manually to extract the seeds,

washed in running water and surface dried for one day at 30 ± 1 °C. The black dry fruits

were processed in a hand operated custom made decorticator which breaks open the dry

fruits to release the seeds.

2.1.2.2 Estimation of Oil content

The seeds were ground using mortar and pestle and 20 g of coarse seed

powder was taken for oil extraction. Commonly used solvent extraction method in

Soxhlet apparatus was applied, using Petroleum ether (boiling point: 40 to 60 °C) as

solvent for extraction of oil as per AOAC 920.39C method (AOAC, 2007). In the present

study, whole seeds were used for oil extraction. After six continuous hours of extraction,

the solvent was recovered by simple distillation and the residual oil was allowed to cool


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in a desiccator and weighed. The percentage of oil in the sample was calculated as

follows,

Percentage oil yield = Weight of the extracted oil x 100 Weight of the seed sample

2.1.2.3 Characterization of oil

a. Determination of Specific gravity

Specific gravity was measured at 25°C using the specific gravity bottle based

on AOCS method Cc 10a-25 (AOCS, 1993). The specific gravity was calculated using

the following equation,

Specific gravity = Weight of bottle and oil sample - Weight of empty bottle Weight of bottle and water – Weight of bottle

b. Determination of Viscosity

The specific viscosity (at 30 °C) of oil samples was measured using Engler

Viscometer and expressed in Degree Engler (°Engler) according to ASTM D1665-98

(2003) standard. Viscosity of oil is defined as the ratio of time of flow for 50 ml of oil in

seconds using an Engler viscometer at a selected temperature to the time of flow, in

second, for an equal volume of water at 25 °C.

c. Determination of Refractive Index

Refractive index of oil was determined using the Abbe refractometer. The

refractometer was first standardized to 1.3333 using distilled water at a temperature of

30°C. This water was cleaned off with tissue paper and replaced with about 0.5 g of oil


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sample. The dark and light regions of the refractometer were adjusted to meet at an

intercept of a crossbar before the readings were taken (Ringler and Maroti, 1994).

d. Determination of Acid value

The oil samples were subjected to chemical characterization for acid value

(Cox and Pearson, 1962; AOAC, 2007) an important indicator of vegetable oil quality

(Kardash and Tur’yan, 2005). Acid value is expressed as the amount of potassium

hydroxide (in milligrams) necessary to neutralize free fatty acids contained in 1 g of oil.

Acid value was determined for each oil sample by dissolving 0.20g of each

oil in 2.5 ml of 1:1 v/v ethanol: diethyl ether solvent and titrating with 0.1N sodium

hydroxide (NaOH) while swirling using phenolphthalein as indicator. Calculation is as

follows,

Acid value = {56.1× N× V} W

Where, N = Normality of NaOH used

V = Volume (ml) of NaOH used

W = Weight of sample used

e. Determination of Saponification value

Saponification value which is a measure of fatty acid chain length in oils was

determined (Horowitz, 1975; AOAC, 2007) and expressed in milligrams of potassium

hydroxide absorbed per gram of oil, 1g of each oil was dissolved in 12.5 ml of 0.5%

ethanolic potassium hydroxide and the mixture refluxed for 30 minutes. 1 ml of


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phenolphthalein indicator was added and the hot soap solution titrated with 0.5N

hydrochloric acid. A blank determination was also carried out under the same condition

and saponification value determined using the following equation,

Saponification value = 56.1N (V1 –V2) W

Where, N = Normality of Hydrochloric acid used

V1 = Volume of Hydrochloric used in test

V2= Volume of Hydrochloric acid used in blank

W = Weight of oil used (1g)

f. Determination of Peroxide value

Peroxide value was determined (Cox and Pearson, 1962; AOAC, 2007) and

expressed in milli Eq / Kg of oil is an index of fatty acid oxidation.

For peroxide value, 1g of each oil sample was weighed into a 200 ml conical

flask then 25 ml of 2:1 v/v glacial acetic acid chloroform solvent was added 1 ml of

saturated potassium iodine was then added and mixture left in the dark for 1 minute.

Next, 30 ml of water was added and the mixture titrated with 0.02N thiosulphate solution

using 5 ml starch as indicator. A blank determination was similarly carried out. Peroxide

Value was calculated from the equation,

Peroxide value = {100 (V1-V2) mg/kg} W


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Where, W = weight of sample

V1 = volume (ml) of thiosulphate used in test

V2 = volume (ml) of thiosulphate used in blank

2.1.2.4 Germination test

Germination test was conducted on sand medium in the nursery (32 ± 2°C;

RH: 65 ±2 %) (ISTA, 1993). The test was carried out with 4 replications of 100 seeds

each. The final count of germination test was taken after 40 days of sowing. The

germination data were transformed to Arc sine values prior to statistical analysis.

2.1.2.5 Statistical analysis

The experiments were carried out in Completely Randomized Design with

four replications each. Two-way ANOVA was used to test the effect of fruit maturity and

seed source on oil content, oil characteristics and germination percentage. Means that

exhibited significant differences were compared at 5% level of confidence (α = 0.05)

(Panse and Sukhatme, 1995).

2.1.3 Results

Effect of fruit maturity on oil content

Oil content among the three different maturity classes did not show any

significant difference as seen in Table 6. From the Table 7 it could be observed that the

quantity of Jatropha oil extracted from seeds of yellow, black pulpy and black dry fruits

were 30.82%, 30.0% and 29.06% respectively (Figure 7).


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Effect of fruit maturity on physical characteristics of oil

The values recorded for physical properties of oil namely viscosity, specific

gravity and refractive index have been presented in Table 8. Viscosity of oil was

observed to vary noticeably among the different maturity stages. The lowest viscosity

(9.925) was recorded by oil from yellow fruits followed serially by black pulpy and black

dry fruits. There was no variation in specific gravity of oil in the three maturity

treatments. Significant variation in refractive index was seen with yellow at 1.4659, black

pulpy at 1.4658 and black dry at 1.4656 (Table 7 and Figure 8).

Effect of fruit maturity on chemical characteristics of oil

Significant differences obtained for chemical properties of oil have been

tabulated in Table 6. The values for chemical properties of oil are presented in Table 9.

The mean for acid value of Jatropha oil from yellow, black pulpy and dry fruits were

observed to be 4.85, 5.00 and 5.00 respectively showing no significant variations among

maturity stages. Similarly, saponification value also did not vary among the maturity

treatments showing values of 126.1, 135.3 and 119.3 for yellow, black pulpy and black

dry respectively. But peroxide value was appreciably influenced by maturity stage with

lowest Peroxide value (3.59) recorded by yellow fruits followed by black pulpy (4.94)

and black dry fruits (5.04) (Figure 9).


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Effect of fruit maturity on germination percentage

Germination percentage varied significantly for different maturity stages.

Both yellow and black pulpy maturity status showed equally high germination of 77.19

and 74.19 % respectively while black dry recorded the least with 62.38 % germination

(Table 10 and Figure 10).

Effect of seed source on oil content

Oil content showed conspicuous variation among the sources (Table 6). The

highest oil content of 32.39 % was recorded by L1 and the lowest (24.80%) by L4 (Table

7) (Figure 7).

Effect of seed source on physical characteristics of oil

The physical properties of oil such as specific gravity and viscosity were

significantly influenced by the source of collection (Table 6). The ranking in ascending

order for specific gravity was as follows: L4, L3, L1 and L2 corresponding to values

0.8553, 0.8947, 0.9188 and 0.9457 respectively. Oil from L4 had the lowest viscosity

(8.761) while L1 showed the highest (12.877) (Table 8 and Figure 8).

Effect of seed source on chemical characteristics of oil

All the three chemical properties namely acid value, saponification value and

peroxide value varied significantly with source (Table 6). Acid value were at parity for

L1 and L2 (5.33 and 5.38 respectively) while L3 and L4 were at balance (4.43 and 4.67

respectively). L4 recorded very high saponification value (149.1) while the other three


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locations were at par with each other. Low peroxide values were observed in L4 and L2

sources while both L1 and L3 showed very high peroxide value (5.96) (Table 9 and

Figure 9).

Effect of seed source on germination percentage

Germination percentage varied significantly among sources (Table 6). Mean

germination percentage for the sources ranged from 52.67 to 89.17 % as evident from

Table 10. The maximum germination was recorded by L2 and the minimum by L3

(Figure 10).


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Table 6. ANOVA for effect of fruit maturity on oil content, oil characteristics and germination

percentage

Character Source of variation Mean

square

F ratio F

probability

Oil % Maturity 12.35 0.95 0.396

Source 145.56 11.21 <.001

Maturity x Source 68.35 5.26 <.001

Specific gravity

Maturity 0.0013098 1.72 0.194

Source 0.0176445 23.14 <.001


Viscosity at 30°C

(°Engler)

Maturity 33.60636 686.40 <.001

Source 44.83192 915.68 <.001


Refractive Index (nD)

Maturity 0.250E-06 9.00 <.001

Source 0.367E-05 132.00 <.001

Maturity x Source 0.917E-06 33.00 <.001

Acid value (mg of KOH/g oil)

Maturity 0.1276 0.22 0.800

Source 2.7465 4.83 0.006


Saponification value (mg of KOH/g oil)

Maturity 1042.9 3.01 0.062

Source 3135.6 9.04 <.001

Maturity x Source 1393.0 4.02 0.004

Peroxide value (milliEq/Kg oil)

Maturity 10.512 9.07 <.001

Source 33.275 28.72 <.001


Germination % Maturity 1716.19 71.80 <.001

Source 763.29 31.93 <.001



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Table 7. Effect of fruit maturity on oil content

Maturity Source Mean for

Maturity L1 L2 L3 L4

Yellow 35.56 35.30 27.63 24.77 30.82

Black pulpy 32.69 31.68 31.67 23.96 30.00

Black dry 24.82 30.19 35.57 25.67 29.06

Mean for source 32.39 31.62 31.02 24.80

S.e.d. C.D.

Maturity 1.274 NS

Source 1.471 2.984

Maturity x Source 2.548 5.168

S.e.d. – Standard error of deviation C.D. – Critical difference NS – Not significant


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Table 8. Effect of fruit maturity on physical characteristics of oil

Source Maturity Specific

gravity

Vicosity at

30°C

(ºEngler)

Refractive

Index (nD)

L1

Yellow 0.8953 11.488 1.4665

Black pulpy 0.9508 13.215 1.4665

Black dry 0.9105 13.927 1.4665

L2

Yellow 0.9453 9.358 1.4665

Black pulpy 0.9088 10.750 1.4655

Black dry 0.9830 13.358 1.4655

L3

Yellow 0.9183 12.285 1.4650

Black pulpy 0.9110 13.300 1.4660

Black dry 0.8548 12.860 1.4650

L4

Yellow 0.8973 6.570 1.4655

Black pulpy 0.8190 8.570 1.4650

Black dry 0.8497 11.143 1.4655

Mean values for maturity

Yellow 0.9140 9.925 1.4659

Black pulpy 0.8974 11.459 1.4658

Black dry 0.8995 12.822 1.4656

Mean values for source

L1 0.9188 12.877 1.4665

L2 0.9457 11.155 1.4658

L3 0.8947 12.815 1.4653

L4 0.8553 8.761 1.4653

Maturity effect S.e.d. 0.0098 0.0782 0.0000589

C.D. NS 0.1587 0.0001195

Source effect S.e.d. 0.0113 0.0903 0.0000680

C.D. 0.0228 0.1832 0.0001380



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Table 9. Effect of fruit maturity on chemical characteristics of oil

Source Maturity Acid value

(mg of

KOH/g oil)

Saponification

value (mg of

KOH/g oil)

Peroxide

value (milli

Eq/Kg oil)

L1

Yellow 6.52 108.7 2.90

Black pulpy 6.46 130.4 10.10

Black dry 6.02 127.9 4.88

L2

Yellow 6.17 110.8 3.75

Black pulpy 5.61 114.3 3.10

Black dry 4.36 106.6 2.97

L3

Yellow 5.61 119.2 4.90

Black pulpy 5.61 125.5 3.07

Black dry 5.27 131.7 9.90

L4

Yellow 5.77 165.5 2.80

Black pulpy 5.05 171.1 3.50

Black dry 6.46 110.8 2.40

Mean values for maturity

Yellow 4.85 126.1 3.59

Black pulpy 5.00 135.3 4.94

Black dry 5.00 119.3 5.04


L1 5.33 122.3 5.96

L2 5.38 110.6 3.27

L3 4.43 125.5 5.96

L4 4.67 149.1 2.90

Maturity effect S.e.d. 0.267 6.58 0.381

C.D. NS NS 0.772

Source effect S.e.d. 0.308 7.60 0.439

C.D. 0.624 15.42 0.891



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Table 10. Effect of fruit maturity on germination percentage

Maturity Source Mean for

maturity L1 L2 L3 L4

Yellow

81.8

(59.1)

92.5

(73.6)

61.0

(79.3)

73.5

(59.1)

77.19

(69.8)

Black pulpy

86.0

(67.1)

94.0

(78.0)

50.0

(72.8)

66.8

(54.2)

74.19

(69.9)

Black dry

74.0

(59.4)

81.0

(61.4)

47.0

(43.3)

47.5

(43.6)

62.38

(51.9)

Mean for

source 80.58

(66.9)

89.17

(71.0)

52.67

(65.1)

62.58

(52.5)

S.e.d. C.D.

Maturity 1.729 3.506

Source 1.996 4.048

Maturity x Source 3.457 7.011

S.e.d. – Standard error of deviation C.D. – Critical difference Values given in parenthesis are arc sine values


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2.1.4 Discussion

Study conducted to find out the fruit maturity indices by collecting fruits at

yellow, black pulpy and black dry fruits showed no significant variation in the percentage

oil content. The yellow fruits were having 30.82% oil while the black dry fruits had

29.06% oil. Although the reduction was not significant, the oil percentage was observed

to reduce as the fruits dry after the optimum stage of collection. Rijssenbeek (2010)

observed low percentage of oil content in dried Jatropha fruits and stated that this could

be because of buildup of free fatty acids (FFA). In the present study, observation in the

different seed source also showed similar reduction in L1 and L2. However, there was an

increase in oil percentage in L3 in dry fruits than the yellow and black pulpy fruits. The

yellow and black pulpy fruits were related to a specific maturity stage of the fruit and the

dried fruits were not related with specific maturity stage, the fruits which are left in the

plant after maturity up to 2-3 months were all counted as dried fruits. Hence dry fruit

collection in L1 and L2 could be a delayed collection and the L3 could be immediately

after drying of the fruits.

The oil content was also observed to vary from location to location from

32.39% in L1 to 24.80% in L4. Similarly, in Jatropha curcas, wide variation of 33.1% of

oil in Gurdaspur (Uttar Pradesh, India) to 14.2% in Hoshiarpur has been reported (Luna

and Sharma, 2006). In Central India, a maximum of 39.12% oil content was observed in

Chhindwara, Madhya Pradesh. In Neem (Azadirachta indica) also such variations in oil

content has been reported among selected plus trees and seed sources (Venkateswaralu et

al., 2000). The oil content studies in Neem, carried out in Tamil Nadu, India was


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reported to have very high heritability values (Kumaran et al., 1993). The variation in

Jatropha for oil content gives immense scope for genetic improvement of this trait.

The analysis of the physical properties of Jatropha seed oil at different fruit

maturity indices showed that there is no significant difference in specific gravity,

however, there was observed a significant increase in viscosity and reduction in refractive

index values from yellow to black pulpy and black dry fruits. Specific gravity describes

the density of a liquid while viscosity implies fluid’s resistance to pouring (De Clerck,

2007). Relative viscosity depends on many factors such as the method of extraction, age

of tree, storage period, degree of saturation and extent of oxidation of the oil being

analyzed (Ikhuoria and Maliki, 2007). Presently increase in viscosity was observed with

increasing maturity despite consistency in the specific gravity of the oil suggesting

changes in fatty acid chains during the process of maturation which may have developed

due to decrease in level of unsaturation of fatty acids. Ikhuoria and Maliki (2007)

observed higher viscosity in Avacado pear oil than African pear oil and related the

increase in viscosity to decrease in unsaturation.

All the physical properties of the oil studied showed significant variation

across locations. The L4 recorded low specific gravity (0.8553) and viscosity (8.761)

values when compared to other locations studied. Highest refractive index (1.4665) was

recorded in L1. Variations in physico-chemical properties of seed oil have been reported

in Jatropha curcas (Parthiban et al., 2011). It could be inferred that L4 with most of the

physical qualities of oil at desirable levels is observed to be relatively better than other

locations as a good seed source.


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Saponification value is inversely proportional to the mean molecular weight

of the glycerides in the oil. The higher the saponification number of an oil and free from

unsaponifiable matter, the more desirable is its quality for biodiesel as it is an indication

that the oil contains more of long chain fatty acids that favours bio-diesel production

(Anonymous, 2003). However no significant difference in Saponification value was

noticed among the different maturity stages.

The Peroxide value was the lowest for oil from yellow fruits than other

maturity stages. Desouky et al. (2009) observed that peroxide values in extracted oils

from Bouteillan and Koroneiki Olive (Olea europaea, L.), cultivars in purple as well as in

black fruits were significantly higher than in those from green fruits which is the initial

ripening stage. Similar observations have also been recorded in the present study wherein

low peroxide values have been recorded in yellow fruits.

The changes in physical and chemical properties of the oil during maturation

implies that these changes could be associated with maturity drying, and, free fatty acids

are subject to auto-oxidation which triggers rapid rancidification of the oil. This also

corroborates with the peroxide values which shows an increasing trend from yellow

towards dry stage. Studies in Nigeria on Blighia sapida fruit oil showed that low peroxide

value of this oil is an indication that it can resist lipolytic hydrolysis and oxidative

deterioration which implies that it is stable oil and could be stored for a longer time when

compared to soybean oil (Oladiji et al., 2009). With increasing auto-oxidation, fatty acids

break down into hydrocarbons, ketones, aldehydes, and smaller amounts of epoxides and

alcohols which results in increased viscosity of the oil as observed in the present study.


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From the present study it could be inferred that with substantial number of desirable

properties such as lower viscosity, higher refractive index and lower peroxide values in

oil from yellow fruits contribute to its superiority over oil extracted from black dry fruits.

At the same time black pulpy fruit stage was observed to rank second to yellow fruit with

respect to oil quality. However, black pulpy fruits need not be neglected while sorting

fruits for oil extraction as it exhibits almost similar influence on oil quality as that of

yellow maturity stage when compared with dry fruits. In the present study, the results

indicate that to obtain good quality oil, fruits need to be harvested at yellow or black

pulpy stage and is safer to avoid collecting completely dry fruits. According to

Rijssenbeek (2010) Jatropha fruits are best harvested when the fruits are yellow in colour.

He also opined that yellow, brown and black fruits are ripe and can be picked as uneven

ripening and long harvesting season are common phenomena in Jatropha. However, time

taken for attaining different maturity stages depend on environmental conditions.

Germination of seed is also affected by maturity as indicated by fruit or seed

colour in some species. The best maturity stage for collecting Madhuca longifolia fruits is

yellowish orange colour (Anandalakshmi, 2010). Fruits of greenish yellow colour have

been reported to possess high percent germination, germination value and energy in

Gmelina arborea (Pandey et al., 2002). Similar assessment were made for various trees

and the most suitable fruit coat colour for obtaining high quality seeds were described as

canary yellow foe Ficus benjamina (Maithani et al., 1987), greenish yellow for

Calophyllum inophyllum (Anandalakshmi, 2010), black for Robinia pseudoacacia

(Bhardwaj et al., 1996), Santalum album (Manonmani and Vanangamudi, 1997),

greenish yellow colour seeds for Azadirachta indica (Bharathi et al., 1996) and yellow


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pods in Albizia (Natarajan, 2007). The present study, also showed concurrent results with

significantly high germination in seeds from yellow fruits which gradually decreased in

black pulpy followed by dry fruits. This reveals that the J. curcas fruits have attained

physiological maturity at yellow maturity stage and can be collected for nursery raising

rather than allowing the seeds to get dried up in the plant. Earlier reports in Jatropha

curcas also envisaged adequate care on collection of seed based on fruit colour at

yellowish brown stage for good germination and vigour (Paramathma and Srimathi,

2006).

The Jatropha curcas fruits requires about 60 days for attaining physiological

maturity. It takes 56 days for formation of yellow fruits and 70 days for black pulpy

stage. Earlier studies conducted in this species also showed similar results. Radhamani

and Srivastava (2009) reported physiological maturity at about 65-70 days and Kaushik

(2003) reported about 57 to 67 days after anthesis as correct maturity stage for seed

collection.


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Figure 7. Effect of seed maturity on the oil content in different seed sources


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Figure 8. Effect of seed maturity on physical characteristics of oil in different seed sources


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Figure 9. Effect of seed maturity on chemical characteristics of oil in different seed sources


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Figure 10. Effect of seed maturity on germination percentage in different seed sources


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2.1.5 Conclusion

The study conducted to determine the appropriate fruit maturity stage

targeting fruit pericarp colour, for obtaining high oil yield of good quality, revealed no

significant change in oil content among the different maturity stages. However,

difference in physico-chemical properties of oil was observed. The seed oil from yellow

fruits possessed low viscosity, high refractive index, and low peroxide value followed

closely by black pulpy stage. Germination was found to be high in seeds from yellow

fruits closely followed by black pulpy fruits. This suggested that yellow and black pulpy

stages of the fruits are appropriate for harvest and it is safe to avoid collection of black

dry fruits. It is all the more important to collect the fruits before they dry on the plant in

order to obtain oil of good quality and seeds with high germination capacity.


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2.2 EFFECT OF SEASON ON SEED OIL AND GERMINATION

2.2.1 Introduction

Prediction of quantity and quality of a potential seed crop and the concurrent

planning of appropriate harvest time and method are essential for efficient allocation of

resources for seed collection (Schimdt, 2000). In most species, flowering and fruiting

occur during definite times of the year according to climatic factors such as rainfall and

temperature. This is particularly pronounced in seasonal climates, i.e. areas with distinct

rainy/dry or hot/cold seasons. In the case of Jatropha curcas it is stated that in general,

flowering occurs during the rainy seasons and the plant flowers twice a year with fruits

maturing 2-3 months after flowering (Green Africa Foundation, 2012). In Thailand for

Jatropha, there are 2 flowering peaks, in November and May. In permanently humid

equatorial regions, flowering occurs in Jatropha throughout the year (Fact Foundation,

2006). Fruit development in Jatropha needs 90 days from flowering until seeds mature

(Orwa et al., 2009). Raina (1984) reported that J. curcas flowers profusely every year

between November and December and sometimes later in May or June. Santos et al.

(2010) reported that a budding and fruiting peak was noticed during the rainy season

suggesting that the vegetative and reproductive events of the Jatropha showed themselves

as seasonal, concentrating on a more intense way its phenological activities during the

rainy season.

Jatropha is not sensitive to day length (flowering is independent of latitude)

and may flower at any time of the year (Heller, 1996). While Jatropha can survive with as

little as 250 to 300 mm of annual rainfall, at least 600 mm are needed for flowering and


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fruiting. The optimum rainfall for seed production is considered between 1000 and 1500

mm (FACT, 2007), which corresponds to sub-humid ecologies. Rainfall induces

flowering and, in areas of unimodal rainfall, flowering is continuous throughout most of

the year. Optimum temperatures are between 20˚C and 28˚C. Very high temperatures can

depress yields (Gour, 2006). Jatropha has been seen to be intolerant of frost. The plant is

well adapted to conditions of high light intensity (Jongschaap et al., 2007) and is unsuited

to growing in shade. Jatropha shows a flowering response to rainfall. After short (one

month) periods of drought, rain will induce flowering. Thus, the cycle of flowering can

be manipulated with irrigation (FACT, 2007). However vegetative growth can be

excessive at the expense of seed production if too much water is applied, for example

with continuous drip irrigation.

Despite variations in the peak flowering and fruiting seasons in Jatropha

curcas, information about the effect of flowering-fruiting season or the phenoperiod on

oil yield and its quality is not available. Seed oil being the end product, it is important to

identify the appropriate season for obtaining quality seeds for the purpose of oil. Hence

this study was undertaken to identify the difference in oil content and its characteristics

over two peak fruiting seasons in Tamil Nadu.

2.2.2 Materials and Methods

2.2.2.1 Collection and processing

Mature black pulpy fruits of J. curcas were collected during two peak fruiting

seasons such as July-August and October –November. Collections were made from 20

individuals in each of the five locations namely, L1-Erode (11° 21' N; 77° 44' E), L2-


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Alandurai (10° 93' N ; 76° 8' E), L3-Nellithurai (11° 19' N ; 77° 56' E), L4-Puliampatty

(11° 28’ N ; 77° 26’) and L5-Pollachi (10° 39' N ; 77° 03' E). The fruits were processed

manually to extract the seeds. Seeds collected from individual trees within a location for

each season were pooled.

Samples were randomly taken for assessing the oil content (details provided in

2.1.2.2 of chapter 2) and germination test. The physical properties viz., viscosity, specific

gravity and refractive index and the chemical properties viz., acid value, saponification

value, iodine number and peroxide value were also analysed (details provided in 2.1.2.4

of chapter 2).

2.2.2.2 Germination test

Germination test was conducted on sand medium in the nursery (32 ± 2°C;

RH: 65 ±2 %) (ISTA, 1993). The test was carried out with 4 replications of 100 seeds

each. The final count of germination test was taken after 40 days of sowing. The

germination data were transformed to Arc sine values prior to statistical analysis.

2.2.2.3 Statistical analysis

The experiments were carried out in Completely Randomized Design with

four replications each. Two-way ANOVA was used to test the effect of season and seed

source on oil parameters and germination percentage. Means that exhibited significant

differences were compared at 5% level of confidence (α = 0.05) (Panse and Sukhatme,

1995).


94

2.2.3 Results

Effect of season on oil content and physical characteristics of Jatropha oil

The oil content recorded during the second season (October-November) was

30.76% and was found to be significantly higher than the quantity obtained during the

first season (July-August) 25.80% (Table 11 and Table 12). The oil content was high in

second season by 8.17 to 3.92% in four out of five locations, except L2 (Figure 11).

The mean values for physical properties of oil, namely, specific gravity and

viscosity of the oil were observed to be comparatively higher during the first season

(0.890; 9.236) than that of the second season (0.823; 9.01) respectively. The mean

refractive index was only slightly higher in the second season than the first season.

However, across difference locations the first and the second season values for viscosity

and refractive index were highly variable. But the specific gravity was uniformly higher

in the first season across all the locations (Tables 11 and 13) (Figure 12).

Effect of season on chemical characteristics of Jatropha oil

Except for peroxide value, other chemical characteristics such as acid value

and saponification value varied significantly across the two fruiting seasons (Table 11).

High acid value (6.21) and low saponification value (155.1) were recorded for the oil of

the first season while the second season showed values of 3.51 and 163.5 for the same

properties respectively. The acid value was uniformly higher in first season across all the

locations. Whereas, the saponification value and peroxide value were highly variable

across difference locations in the first and the second seasons (Table 14 and Figure 13).


95

Effect of season on germination percentage

A significant variation was observed between the mean germination

percentage of first and second season with 75.5 and 28.0% respectively. In all the studied

locations, the germination percentage was high for the first season collected fruits than

that of the second season. During the first season, high germination was observed in L3

and L2 with about 90 and 85% germination respectively and relatively low germination

was observed in L4 with 57.5%. During the second season, high germination of 52.5%

was obtained in L5 and very low germination was observed in L2 with 10% germination

(Tables 11 and 15) (Figure 14).


96

Table 11. ANOVA for effect of season on oil content, oil characteristics and germination

percentage

Character Source of

variation

Mean square F ratio F

probability

Oil % Season 245.4707 325.71 <.001

Source 79.9072 106.03 <.001

Season x Source 42.0800 55.83 <.001

Viscosity at 30°C

(°Engler) Season 10.43564 580.12 <.001

Source 10.63012 590.94 <.001

Season x Source 12.43032 691.01 <.001

Specific gravity Season 0.0555770 130.54 <.001

Source 0.0050832 11.94 <.001

Season x Source 0.0028395 6.67 <.001

Refractive Index (nD)

Season 0.900E-06 17.36 <.001

Source 0.838E-06 16.15 <.001

Season x Source 0.509E-05 98.12 <.001

Acid value (mg of KOH/g oil)

Season 8.057 4.97 0.034

Source 20.960 12.92 <.001

Season x Source 65.021 40.07 <.001

Saponification value (mg of KOH/g oil)

Season 708.12 63.28 <.001

Source 1369.82 122.41 <.001

Season x Source 881.22 78.75 <.001

Peroxide value (milliEq/Kg oil)

Season 0.7840 3.19 0.085

Source 2.1040 8.56 <.001

Season x Source 1.3040 5.30 0.003

Germination % Season 10349.09 126.86 <.001

Source 320.39 3.93 0.011

Season x Source 624.88 7.66 <.001


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Table 12. Effect of season on oil content

Season Source Mean

for

season L1 L2 L3 L4 L5

July-August 28.11 29.91 25.03 21.16 24.79 25.80

October-November

35.47 27.26 33.02 25.08 32.96 30.76

Mean for

source 31.79 28.58 29.02 23.12 28.88

S.e.d. C.D.

Season 0.275 0.563

Source 0.434 0.891

Season x Source 0.614 1.260

S.e.d. – Standard error of deviation C.D. – Critical difference


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Table 13. Effect of season on physical characteristics of oil

Season Source Specific

gravity

Viscosity at

30°C (°Engler) Refractive

Index (nD)

July-August L1 0.877 10.07 1.4650

L2 0.910 9.29 1.4660

L3 0.896 7.86 1.4650

L4 0.846 9.71 1.4650

L5 0.923 9.25 1.4660

October-November

L1 0.806 8.86 1.4660

L2 0.845 9.32 1.4640

L3 0.802 8.93 1.4670

L4 0.820 8.43 1.4670

L5 0.843 9.54 1.4650

Mean values for season

July-August 0.890 9.236 1.4650

October-November 0.823 9.010 1.4660


L1 0.841 9.465 1.4650

L2 0.878 9.300 1.4650

L3 0.849 8.393 1.4660

L4 0.833 9.071 1.4660

L5 0.883 9.393 1.4650

Season S.e.d. 0.007 0.424 0.0001

C.D. 0.013 0.087 0.0002

Source S.e.d. 0.010 0.647 0.0001

C.D. 0.021 1.376 0.0002

Season x Source S.e.d. 0.015 0.095 0.0002

C.D. 0.030 0.195 0.0003

S.e.d. – Standard error of deviation C.D. – Critical difference


99

Table 14. Effect of season on chemical characteristics of oil

Season Source Acid value mg

of KOH

Sap. value mg

of KOH

Peroxide value

milli Eq/Kg

July-August L1 7.293 122.02 2.00

L2 6.366 176.72 1.40

L3 5.610 161.29 3.60

L4 7.293 162.69 2.40

L5 4.488 152.87 2.60

October-November L1 2.244 157.08 2.20

L2 6.342 159.89 2.80

L3 2.244 185.13 2.80

L4 3.366 158.48 2.60

L5 3.366 157.08 3.20

Mean values for season

July-August 6.21 155.1 2.40

October-November 3.51 163.5 2.68


L1 4.77 139.55 2.00

L2 6.35 168.30 2.10

L3 3.93 173.21 3.20

L4 5.33 160.59 2.50

L5 3.93 154.98 2.90

Season S.e.d. 0.403 1.058 0.1568

C.D. 0.826 2.170 NS

Source S.e.d. 0.637 1.673 0.2480

C.D. 1.307 3.432 0.5088

Season x Source S.e.d. 0.901 2.365 0.3507

C.D. 1.848 4.853 0.7195



100

Table 15. Effect of season on germination percentage

Season Source Mean for

season L1 L2 L3 L4 L5

July-August 67.5 (55.3)

85.0 (67.3)

90.0 (74.1)

57.5 (49.3)

77.5 (62.1)

75.5

(61.7)

October-November

25.0 (29.9)

10.0 (13.3)

25.0 (26.3)

27.5 (31.6)

52.5 (46.5)

28.0

(29.5)

Mean for

source 46.2

(42. 6)

47.5

(40. 3)

57.5

(50.2)

42.5

(40.4) 65.0

(54.3)

S.e.d. C.D.

Season 2.86 5.83

Source 4.52 9.22

Season x Source 6.39 13.04

S.e.d. – Standard error of deviation C.D. – Critical difference Values given in parenthesis are arc sine values


101

2.2.4 Discussion

Studies conducted during two fruiting seasons of Jatropha in five different

locations showed significant variation in oil content and germination for these seasons.

There are two clear fruiting seasons, July-August and October-November. These two

seasons corresponds with two major rainy seasons during June-July and October-

November in Tamil Nadu with a long dry spell before first season and strong winds in

between these two rainy seasons. Although the amount of rainfall received is different

across the locations, the first season receives lesser rain when compared to second season

during October to November. However, the flowering and fruiting is profuse during the

first rainy season.

The present study showed high germination during the first season (July-

August) and high oil content during second season (October-November). The good

germination in first season could be related with profuse flowering which supports better

cross pollination than the second season in which there was poor flowering and increased

chances of self pollination. Similar studies conducted in Neem showed that sporadic

fruiting during September – December resulted in high incidence of abortive seeds when

compared to profuse fruiting season of June- July (Nagaveni and Rengasamy, 1996). In a

study on reproductive biology of Neem by Vikas and Tandon (2011) it was observed that

a few trees had a second flush of flowering that yielded no fruits.

In general, flowering is known to be induced by a shower after a long dry

spell. It is similarly reported in Jatropha that induction of flowering begins with onset of

the rainy season after a dry period (Fact Foundation, 2006). Santos et al. (2010) reported


102

that budding and fruiting are seasonal and coincides with rainy season with more intense

phenological activities. Heavy wind and rain are observed to affect the flowering and

subsequent fruiting in many species as in the case of Olive (Olea europaea), where,

strong winds and rain have been reported to hinder pollination (Rapoport, 1998). In the

present study also, the fruit collection was high during the first season when compared to

the second season. The profuse flowering enables sufficient pollen availability for better

cross pollination and seed filling. The self pollinated seeds are reported to have ill filled

or under developed seeds leading to poor germination.

On the contrary, the oil content was observed to be higher in the second

season than the first. Although the oil content was high, the overall fruiting in this season

was less. Hence it is inferred that an individual seed receives more nutrient from the plant

during poor fruiting season than heavy fruiting season, leading to high oil formation

during the poor fruiting season. There are studies in species like Olive (Olea europaea)

that shows that the oil content and profuse fruiting are negatively correlated. Lavee

(2007) suggested that every stage of developmental cycle of Olive is affected by the

previous one, and also the one that follows. So, the level of fruit set will affect not only

the differentiation ability for the following season, but also the characteristics of the fruit

in the present one such as fruit size, time of maturation, and as a result the rate of oil

accumulation. It was reported in Olive, that heavy yield during a season will lead to

small, late maturing fruit and also a slower rate of oil accumulation. This coincides with

the present study where during the first season, the seed production was higher but the oil

content was lower compared to the second. Studies conducted in different varieties of

Sunflower in Turkey showed linear positive relationship between seed yield and oil


103

content in a variety “Tarsan 1018”, but the rate of seed yield of another variety “Sanbro”

and the control hybrids decreased with increasing oil content up to 45% oil content rate

and then increased beyond this point (Kaya et al., 2007). In contrast, studies conducted

by Machikowa and Saetang (2008) in sixteen varieties of Sunflower at Thailand revealed

that there is no relationship between oil content and seed yield.

Studies on various physical and chemical properties of the oil sampled during

first and second season in five different locations indicated that the specific gravity was

consistently low in the second season. Low specific gravity of oil is a preferable character

for using both as Straight Vegetable Oil and biodiesel. Between these two seasons there

is about 7.5% reduction in specific gravity during the second season. The reduction in

specific gravity of the oil during the second season could be due to change in the relative

fractions of different fatty acids and their association with hydroxyl groups. The hydroxyl

groups have direct relationship with specific gravity (Asuquo et al., 2012). Specific

gravity is a measure of qualitative changes in oils, which decreases with increasing chain

length and decreasing degree of unsaturation of oil (Beckett and Stenlake, 2004).

Similarly oil sampled during first and second season in five different

locations indicated that acid values were consistently better in the second season. It

corresponds to the amount of potassium hydroxide needed to neutralize free fatty acids.

Lower acid value is an indication of lesser possibility for rancidity. Acid value can also

be used to check the level of oxidative deterioration of the oil by enzymatic or chemical

oxidation (Asuquo et al., 2010). In the present observation, the lower acid value could be

related to lower amount of free fatty acid in the oil.


104

Figure 11. Effect of season on the oil content in different seed sources


105

Figure 12. Effect of season on the physical characteristics of oil in different seed sources

Source

Source

Source

o


106

Figure 13. Effect of season on the chemical characteristics of oil in different seed sources

Aci

d v

alu

e m

g o

f K

OH

Source

Source

Sa

po

nif

ica

tio

n v

alu

e m

g o

f

KO

H

Source

Pe

rox

ide

va

lue

mil

li E

q/K

g


107

Figure 14. Effect of season on the germination percentage in different seed sources


108

2.2.5 Conclusion

The first season has given high germination while the second season resulted

in high oil percentage. The physico-chemical characteristics of the oil were also better for

the second season. The general observation on the over all seed production was found to

be better during the first season than the second. Although the oil content was high during

the second season the over all oil recovery was low due to poor seed production. Hence it

is suggested that seeds can be harvested during the peak fruiting season (first season), as

collection of fruits during the peak fruiting period would be more economical than

collecting seeds during the sparse fruiting season.


chapter 2 fruit maturity indices and...

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