screening for varietal resistance of brinjal against...
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Introduction
Brinjal being native to India is one of the most common vegetable crops of the
country and it is also called poor man‟s vegetable. Brinjal is grown for its unripe,
immature fruits, which are used as cooked vegetable and in curries. In the areas
experiencing high temperature and humidity during rainy season, the production
of brinjal suffers immensely due to the attack of disease and insect pests. Among
the diseases threatening the cultivation of brinjal, Phomopsis leaf blight and fruit
rot are the most serious disease as this can affect at any stage of its development
and lead to complete loss of the crop. The pathogen usually soil as well as seed-
borne and therefore it is very difficult to manage the disease by chemical control
method alone. Chemical management of the disease also leaves behind the many
toxic residues in the soil affecting the consumers‟ health.
In view of these, there is need for search for innate durable resistance in brinjal
cultivars, so that same cultivars could be used for growing as well as breeding
purpose for further improvement. Studies conducted to screen for resistant
varieties of brinjal against P.vexans met with little success. Hence in the present
study an attempt has been made screen popular varieties of brinjal for durable
resistance against Phomopsis vexans.
Materials and Methods
Collection of Brinjal Samples
A total of 16 cultivars were collected from different sources including agro-
traders and farmers. The most widely cultivated cultivar in Karnataka is Brinjal
cv. purple pusa long, Manju (F1 Hybrid) Hybrid, Ankush green long, MEBH9,
MEBH10, Brinjal Seeds (Green round) and Kalpataru hybrid seeds. The list of
brinjal cultivars used in the present study for varietal resistance is presented in
Table-3.0.
Preparation of fungal inoculum
Fourteen (14) day old culture of Phomopsis vexans was isolated on Potato
Dextrose Agar medium from fruit rot and leaf blight affected brinjal sample. The
pure culture was used for inoculum preparation. Using sterile needle, pycnidia
were dislodged into sterile distilled water. The suspension was filtered through
cheese cloth to remove bigger particles. The alpha conidial suspension was
adjusted to 1x105 conidia/ml using Haemocytometre and used for foliar spray
using glass automizer.
Screening for resistant cultivars of brinjal under green house conditions
A total of 16 commercial cultivars of brinjal seeds were used in the present
investigation for screening for the resistance under green house condition.
Seedlings were raised in nursery and were transferred to pots filled with sterilized
soil, farmyard manure and sand (2:1:1). Twenty five 25 day old seedlings were
sprayed with conidial suspension of Phomopsis vexans and initiation of leaf blight
and fruit rot symptoms were recorded after 10 days post inoculation until the crop
reached harvest stage. Based on the incidence of leaf blight and fruit rot disease
on each cultivar, disease incidence and nature of resistance of each cultivar was
determined. The disease resistance/susceptibility of each cultivar was recorded.
Seedlings inoculated with sterile water served as control.
Evaluation of varietal resistance against P. vexans in field condition
A total of 16 commercial cultivars used earlier in green house experiment were
also evaluated under field conditions in farmer fields situated near Mysuru
(Marayyanahundi). The field blocks were 2.5x3m (length and width). Seedlings
of all 16 cultivars were raised in nursery and 35days old seedlings were
transferred to fields. A total of 90 seedlings were planted for each cultivar (9 rows
and 10plants/row). After 30 days of transplantation and with all agronomic
practices, conidial suspension of P. vexans was sprayed and initiation of leaf
blight and fruit rot symptoms were observed after 10 days post inoculation until
the crop reached harvest stage. Development of fruit rot disease was observed
after 50-60 days of post inoculation.
Table: 3.0. List of Brinjal cultivars used in the present investigations for
screening resistant cultivars.
Sl. No Cultivar/Variety Origin/Producer
01 Hybrid Brinjal seeds MEBH 10-Super 10 Mahyco®, Mumbai, India
02 Malapur -Mrityunjaya seeds Mrityunjaya Seed corporation, Dharwad, Karnataka, India
03 Hybrid Brinjal seeds- Kamadhenu Tanindo Seed Pvt. Ltd. Banglore, India.
04 Hybrid Brinjal seeds MHB 11 (Improved) Mahyco®, Mumbai, India
05 Hybrid Brinjal Ankush- BRANK25-1227 Srujana Seeds Pvt. Ltd. Banglore, India.
06 Hybrid Egg Plant- Manju (F1 Hybrid) Syngenta India Limited, Mumbai, India.
07 Brinjal F1- Hybrid Jyothi Prabhakar Hybrid Seeds, Banglore, India
08 Brinjal- Brinjal Varikathri Nethra Seeds Corporation, Banglore, India.
09 Hybrid Brinjal Seeds- MEBH 11 Mahyco®, Mumbai, India
10 Brinjal Seeds (Green round) Sagar Hybrid Seeds Company, Hyderabad, India.
11 Brinjal- Pusa Purple Long. National Seed Corporation Ltd. New Delhi, India
12 Brinjal seeds- Ruchika Pradham Biotech Pvt. Ltd Hyderabad, India
13 Kalpataru- Hybrid Brinjal Seeds MEBH10 Mahyco®, Mumbai, India
14 F1 Hybrid Brinjal SBH- Sarpan brinjal
Seeds
SARPAN Hybrid seeds Co. Pvt. Ltd, Dharwad, Karnataka
15 Local Brinjal Seeds* Doddamaragowdanahally, Mysuru, Karnataka, India
16 Local Brinjal Seeds* Netkalu, Malavally, Mandya, Karnataka, India.
*Seed samples processed by farmers for recycle purpose were procured directly
and were preserved at 4˚C for further use.
Disease scale for calculating leaf blight disease and fruit rot disease
As there is no disease assessment scale available for brinjal, a disease scale has
been developed to calculate the leaf blight disease and fruit rot disease. For the
assessment of leaf blight disease, a disease scale of 0-5 was used (0- highly
resistant, 1-5-resistant, 6-15-moderately resistant, 16-30 intermediate, 31-60-
suseptible, > 61-Highly susceptible respectively. Similarly, a disease scale of 0-5
was used for fruit rot disease assessment. The disease scale of 0-5 (0-highly
resistant, 1-20 resistant, 21-40 moderately resistant, 41-50 intermediate, 51-70,
susceptible, 71-100-highly susceptible was used. This scale has been used to
calculate disease incidence on leaf and fruit of brinjal. The disease scale used for
assessing leaf blight and fruit rot disease is presented in Table-3.1 (Mrindha et al.
(2007).
Table: 3.1. Disease scale for leaf blight and fruit rot disease of brinjal against
Phomopsis vexans.
Severity
Scale
for leaf
Leaf
surface
affected
(%)
Nature of resistance/
susceptibility
Fruit surface
affected (%)
Severity
Scale for
fruit
0 0 Highly Resistant (HR) 0 0
1 1-5 Resistant (R) 1-20 1
2 6-15 Moderately Resistant MR 21-40 2
3 16-30 Intermediate (I) 41-50 3
4 31-60 Susceptible (S) 51-70 4
5 61-100 Highly Susceptible (HS) 71-100 5
Results
Screening for resistance under green house condition
The results of cultivar screening for leaf blight disease of brinjal are provided in
Table 3.0 and Fig. 3.1 respectively. A total of 16 cultivars were screened under
green house condition with conidial application of P. vexans. The study revealed
that, very high incidence of leaf blight disease of 84% and 82% was recorded in
two local cultivars of brinjal followed by 78% in Malapur cultivar. Low incidence
of leaf blight disease of 11% and 22% were recorded in MEBH10 and MEBH11
cultivars respectively. Similarly the incidence of fruit rot disease was also
evaluated on 16 cultivars based on the fruit rot disease incidence. The study
showed that high incidence of fruit rot disease of 72% and 69% was recorded in
two local cultivars of brinjal followed by incidence of 64% in Malapur cultivar.
Very low incidence of fruit rot disease of 14% and 22% were recorded in two
hybrid cultivars namely MEBH10 and MEBH11 respectively.
Based on the screening method adapted under green house condition for leaf
blight disease all the 16 cultivars were classified as 4-highly susceptible cultivars
(> 61%), 7-susceptible (31-60%), 4-intermediate (16-30%) and 1 moderately
resistant (6-15%) respectively for leaf blight disease. More or less similar trend
was observed in all the 16 cultivars when screened against fruit rot disease under
green house condition. Out of 16 cultivars, 4-highly susceptible (71-80%), 7-
susceptible (51-70%), 4-intermediate (41-50%) and 1-moderately resistant (21-
30%) cultivars were found. No cultivar was found resistant or blight resistant
among 16 cultivars screened against fruit rot disease.
Screening for varietal resistance under field condition
The results of field evaluation of brinjal cultivars for leaf blight and fruit rot
disease is presented in Table-3.2 and Fig. 3.3, 3.5 & 3.4 respectively. Out of 16
cultivars screened for leaf blight disease four cultivars were highly susceptible to
leaf blight disease. The study revealed that, very high incidence of leaf blight
disease of 68% and 74% was recorded in Malapur and one local cultivars of
brinjal. Lower incidence of leaf blight disease of 9% was recorded in MEBH10
cultivar. Similarly the incidence of fruit rot disease was also evaluated on 16
cultivars based on the fruit rot disease incidence. The study showed that high
incidence of fruit rot disease of 83 and 84% was recorded in one local cultivar and
Malapur seeds of brinjal followed by incidence of 79% in Local brinjal seeds 16.
Very low incidence of fruit rot disease of 10% was recorded in MEBH10 cultivar.
Based on the screening method adapted under field evaluation, for leaf blight
disease all the 16 cultivars were classified as 4-highly susceptible cultivars
(>61%), 7-susceptible (31-60%), 4-intermediate (16-30%) and 1 moderately
resistant (6-15%) respectively for leaf blight disease. More or less similar trend
was observed in all the 16 cultivars when screened against fruit rot disease under
green house condition. Out of 16 cultivars, 4-highly susceptible (71-80%), 7-
susceptible (51-70%), 4-intermediate (41-50%) and 1-moderately resistant (21-
30%) cultivar was found. No cultivar was found resistant or highly resistant
among 16 cultivars screened against fruit rot disease.
Discussion
Plants are endowed with different types of resistance, so also many crop plants.
Durable resistance is the resistance that remains effective in a cultivar that is
widely grown for a long period of time. It cannot be identified immediately, as it
should be grown for a long time. Durable resistance can be identified based on
relative performance of other cultivars during evaluation or screening. Searching
for durable disease resistance in crop plants has been a continuous process by
which host itself plays the role of an antagonist (Singh, 1975). As many plant
pathogens including fungal pathogens coming with varied degrees of virulence
these days, resistant varieties can be the most simple, practical and effective and
economical method of plant disease control. They also ensure protection against
diseases and also save time, energy and money. For many diseases such as wilts,
rusts, and other viral diseases, resistant varieties are the only practical method of
disease control.
The terms monogenic, polygenic, vertical, horizontal, specific and general
resistance are being used to explain the type of resistance in plants against
invading plant pathogens. Two basic types of resistance mechanisms have been
recognized in plants, they are specific and general resistance. When the defense
mechanism in plants is controlled by a single gene pair it is known as monogenic
resistance. Varieties with monogenic resistance remain completely free from
pathogen attack in different environments. This type of resistance is stable only
until new races of pathogen emerge.
When the resistance is controlled by synergistic action of more than one minor
group of supplementary genes, the type of resistance is known as generalized or
polygenic resistance. The polygenic resistance is likely to disappear with change
in the environments. However, it is more tolerant to evolution of new races of the
pathogen. It remains useful for a longer period. However, resistance developed by
combination of many dominant and recessive genes is more desirable in crop
plants.
During crop improvement programme for disease resistance, three common
methods are employed, namely; selection, mutation and hybridization. Screening
for disease resistance is pre-requisite for breeding programme. As brinjal is one of
the important vegetable crops, and is largely grown in different parts of the
country, it is desirable to have stocks of resistance cultivars for cultivation in
different agro-climatic regions of India, so that the crop could be protected from
existing and new races of pathogen. However, no studies have been conducted for
varietal screening for disease resistance in brinjal against fungal, bacterial or viral
plant pathogens.
In view of the above, in the present study, 16 popular cultivars of brinjal collected
from different sources were screened against P. vexans. Among these very low
incidence of leaf blight disease (11%) was recorded only on Brinjal Hybrid
MEBH10. Similarly the low incidence of fruit rot disease (14%) was also
recorded in cultivar MEBH10. Hence the study showed that cultivar MEBH10 to
certain extent showed moderate resistance against P. vexans the causative agent of
leaf blight disease. Similarly, among 16 cultivars of brinjal screened under field
evaluation for leaf blight and fruit rot disease, low incidence of leaf blight and
fruit rot disease were recorded in MEBH10 cultivar. None of the other cultivars
exhibited some degree resistance to leaf blight and fruit rot disease. The present
study clearly identified the moderately resistant MEBH10 variety only to certain
extent against P. vexans. Similar studies on resistance to Phomopsis fruit rot in
brinjal was investigated by Datar and Ashtaputre (1988). Studies on resistance to
Phomopsis blight in brinjal were also studied by Kalda et al. (1976). Phomopsis
blight in brinjal and sources of resistance was also studied by Pandey et al.
(2002). Test on brinjal resisting to Phomopsis rot was studied by Ren and Zhang
(1993). Further, control of Phomopsis fruit rot of brinjal with different fungicides
and also economics was studied by Grewal and Jhooty (1987); Islam and Pan
(1989 and 1993). Efficacy of certain fungicides in controlling Phomospsis vexans
causing fruit rot of Brinjal was studied by Mohanty et al. (1994). However no
durable resistance was discovered.
Brinjal is the leading vegetable in the country in terms of hectare and volume of
production in India. It is a very versatile vegetable which can be taken alone as a
dish or mixed with other vegetables. Its production constraint is the Phomopsis
blight which is caused by Phomopsis vexans (Sacc and Syd) Harter. The disease is
seed-borne and can cause disease in the next season. Host resistance is the most
practical and environment-safe method against this pathogen. The present study,
though identified MEBH10 cultivar is moderately resistant to P. vexans. The
degree of resistance may not be sufficient to protect the brinjal crop against fungal
pathogen. Therefore, further, work needs to be carried out to identify the durable
resistance to P.vexans.
Table: 3.2. Brinjal cultivars inoculated with conidial suspension of Phomopsis
vexans to record the disease incidence and severity under green house
condition for leaf blight and fruit rot disease.
Sl.
No.
Cultivar/Variety Source Leaf
Blight
(%)
Nature of
resistance
Fruit Rot
Disease
(%)
Nature of
Resistance
01 Hybrid Brinjal seeds MEBH 10-Super 10
Mahyco®, Mumbai, India
11 MR 14 MR
02 Malapur -Mrityunjaya seeds
Mrityunjaya Seed corporation, Dharwad, Karnataka, India
78 HS 64 HS
03 Hybrid Brinjal seeds- Kamadhenu
Tanindo Seed Pvt. Ltd. Banglore, India.
23 I 22 I
04 Hybrid Brinjal seeds MHB 11 (Improved)-Bulldozer
Mahyco®, Mumbai, India
52 S 39 S
05 Hybrid Brinjal Ankush- BRANK25-1227
Srujana Seeds Pvt. Ltd. Banglore, India.
24 I 18 I
06 Hybrid Egg Plant- Manju
(F1 Hybrid)
Syngenta India
Limited, Mumbai, India.
42 S 54 S
07 Brinjal F1- Hybrid Jyothi Prabhakar Hybrid Seeds, Banglore, India
51 S 36 S
08 Brinjal- Brinjal Varikathri Nethra Seeds Corporation, Banglore, India.
64 HS 65 HS
09 Hybrid Brinjal Seeds- MEBH 11
Mahyco®, Mumbai, India
22 I 24 I
10 Brinjal Seeds (Green round)
Sagar Hybrid Seeds Company, Hyderabad, India.
46 S 37 S
11 Brinjal- Pusa Purple
Long.
National Seed
Corporation Ltd. New Delhi, India
59 S 49 S
12 Brinjal seeds- Ruchika Pradham Biotech Pvt. Ltd Hyderabad, India
27 I 25 I
13 Kalpataru- Hybrid Brinjal Seeds MEBH10
Mahyco®, Mumbai, India
55 S 38 S
14 F1 Hybrid Brinjal SBH- Sarpan brinjal Seeds
SARPAN Hybrid seeds Co. Pvt. Ltd, Dharwad, Karnataka
58 S 42 S
15 Local Brinjal Seeds Doddamaragowdanahally, Mysuru, Karnataka, India
82 HS 72 HS
16 Local Brinjal Seeds Netkalu, Mandya,
Malavally, Karnataka, India.
84 HS 69 HS
Values given are mean of three replicates
(Hybrid Brinjal seeds MHB 11 (Improved)-Bulldozer, Hybrid brinjal- Manju (F1 Hybrid), Brinjal
F1- Hybrid Jyothi, Brinjal Seeds (Green round)
Table: 3.3. Brinjal cultivars inoculated with conidial suspension of Phomopsis
vexans to record the leaf blight and fruit rot disease under field evaluation.
Sl. No Cultivar/Vari
ety
Origin/Producer Leaf
Blight
Disease
incidence
Nature
of the
cultivar
Fruit
Rot
disease
Nature of
the
cultivar
01 Hybrid Brinjal
seeds MEBH
10-Super 10
Mahyco®, Mumbai, India 9 MR 10 MR
02 Malapur -Mrityunjaya
seeds
Mrityunjaya Seed corporation, Dharwad, Karnataka, India
68 HS 84 HS
03 Hybrid Brinjal
seeds-
Kamadhenu
Tanindo Seed Pvt. Ltd.
Banglore, India.
25 I 29 I
04 Hybrid Brinjal
seeds MHB 11
(Improved)-
Bulldozer
Mahyco®, Mumbai, India 44 S 46 S
05 Hybrid Brinjal
Ankush-
BRANK25-
1227
Srujana Seeds Pvt. Ltd.
Banglore, India.
21 I 22 I
06 Hybrid Egg
Plant- Manju (F1 Hybrid)
Syngenta India Limited,
Mumbai, India.
38 S 53 S
07 Brinjal F1-
Hybrid Jyothi
Prabhakar Hybrid Seeds,
Banglore, India
47 S 58 S
08 Brinjal- Brinjal
Varikathri
Nethra Seeds Corporation,
Banglore, India.
69 HS 78 HS
09 Hybrid Brinjal
Seeds- MEBH
11
Mahyco®, Mumbai, India 26 I 21 I
10 Brinjal Seeds
(Green round)
Sagar Hybrid Seeds Company,
Hyderabad, India.
39 S 52 S
11 Brinjal- Pusa
Purple Long.
National Seed Corporation
Ltd. New Delhi, India
41 S 57 S
12 Brinjal seeds-
Ruchika
Pradham Biotech Pvt. Ltd
Hyderabad, India
19 I 19 I
13 Kalpataru-
Hybrid Brinjal
Seeds
MEBH10
Mahyco®, Mumbai, India 55 S 42 S
14 F1 Hybrid Brinjal SBH-
Sarpan brinjal
Seeds
SARPAN Hybrid seeds Co. Pvt. Ltd, Dharwad, Karnataka
47 S 54 S
15 Local Brinjal
Seeds
Doddamaragowdanahally,
Mysuru, Karnataka, India
66 HS 83 HS
16 Local Brinjal
Seeds
Netkalu, Mandya, Malavalli,
Karnataka, India.
74 HS 79 HS
Figure: 3.0. Brinjal seedlings in nursery for varietal screening for resistant
cultivars of brinjal before they are transplanted to fields.
Figure-3.1: Evaluation of brinjal cultivars for varietal screening for
resistance under green house condition.
Figure -3.2 :Evaluation of Brinjal cultivars for varietal screening for
resistance underfield condition near Mysuru.
Figure -3.3: Evaluation of Brinjal cultivars for varietal screening for
resistance under field condition near Mysuru showing leaf blight disease on
local cultivar.