Chapter-3

Screening for varietal resistance of

brinjal against Phomopsis vexans

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.

Figure-3.4: Evaluation of Brinjal cultivars for varietal screening for

resistance under field condition near K. R. Nagar, Mysore District showing

leaf blight disease on local cultivar.