MSc

The project entitled “Evaluation of F2 segregating population of chilli (Capsicum
annuum L.) for yield and resistance to leaf curl virus” was carried out at the Department
of Vegetable Science, College of Agriculture, Vellayani, during summer 2021 to evaluate
the F2 segregants of chilli crosses for yield and leaf curl virus resistance.
In the present study two crosses viz., CHIVAR-6 x Sel-4 and CHIVAR-10 x Sel-3
were selected from the previous PhD research study conducted at the Department of
Vegetable Science, College of Agriculture, Vellayani. The F2 population comprising of
200 segregants from the two crosses along with their parents were raised and evaluated
for various characters and incidence of leaf curl virus.
The results revealed variability among the segregants for various characters
studied. Among the segregants maximum plant height was exhibited by C-2-182 (146.00
cm). The segregants of first cross, C-1-19, C-1-37, C-1-49, C-1-111, C-1-125, C-1-127,
C-1-130, C-1-140 and C-1-163 were the earliest to flower (32.00 days).The days to
harvest ranged from 51 days to 58 days among the segregants of the first cross and 52
days to 58 days in the second cross. The fruits per plant was highest in the segregant C-2-
161 (160) and C-1-149 (103) from both populations. Among the segregant population,
maximum fruit length was noticed in the segregant C-2-42 (10.16 cm) of cross 2 whereas
maximum fruit girth was noticed in C-1-145 (5.03 cm) of cross 1. Fruit pedicel length
was highest in the segregant C-2-68 (4.49 cm). C-1-70 recorded the highest fruit weight
(6.21 g) among the segregant population of the two crosses. C-2-70 had the maximum
number of seeds per fruit of 119.00. Among the F2 population, the highest fruit yield per
plant was exhibited by the segregant C-2-161 (518.79 g) followed by C-2-168 (420.40 g),
C-1-117 (374.18 g) and C-1-151 (363.00 g).
The ascorbic acid content ranged from 36 mg 100 g-1 to 144.00 mg 100 g-1 among
the segregants. The highest carotenoid content was observed in C-1-196 and C- 2-112
(275.67 mg 100 g-1).
In the present study, the scoring for chilli leaf curl virus was done and based on
the scoring the segregants were categorized into highly resistant, resistant, moderately
resistant, moderately susceptible, susceptible and highly susceptible. The coefficient of
infection revealed that both the F2 segregants and their parents displayed highly resistant
reaction to leaf curl virus.
Enzyme analysis assay for peroxidase activity ranged from (12-37) unit activity1min-1 g -1 among the population of the cross 1 and in cross 2, it ranged from (11-47) unit
activity-1min-1 g-1. Phenylalanine ammonia activity ranged from (15.3 µg-1 g-1min-1) to
(28.2 µg-1 g-1min-1) and from (12.6 µg-1 g-1min-1) to (15.4 µg-1 g-1 min-1) in cross 1 and
cross 2 respectively. Polyphenol oxidase activity of the segregant population of cross 1
ranged from 19-32 unit activity-1 min-1 g-1 and in the segregant population of cross 2 it
ranged from 14-23 unit activity-1min-1 g -1
.
The highest percentage of positive segregants in the F2 population of the cross
CHIVAR-6 x Sel-4 was observed for days to first flowering (78 %), yield per plant (52
%), fruits per plant (40.5 %) and seeds per fruit (34.5 %). In the cross CHIVAR-10 x Sel3, highest positive segregation percentage was observed for plant height (81.5 %), yield
per plant (69.5 %) and fruits per plant (56.5 %).
Principal component analysis was carried out for the quantitative characters. Out
of the thirteen principal component axes (PCA)s extracted, six PCAs with eigen values
greater than one were retained for both the cross which accounted for total variation of
64.07 per cent and 67.31 per cent in the cross 1 and cross 2 respectively. The first two
principal components contributed major part of the variation with a proportion of 16.78
per cent and 11.79 per cent in cross 1. In the second cross first two components
contributed 18.95 per cent and 12.66 per cent respectively.
Based on simple correlation study for various characters with yield per plant it
was observed that for the F2 population of CHIVAR-6 x Sel-4 significant positive
correlation was observed for fruits per plant (0.718), plant height (0.292), fruit weight
(0.286) and fruit girth (0.16). F2 population of CHIVAR-10 x Sel-3 exhibited significant
positive correlation for fruits per plant (0.818), plant height (0.286) and fruit length
(0.184) with yield per plant. In case of the parents of cross 1 significant positive
correlation was shown for fruits per plant (0.406).
The chi-square analysis for goodness to fit to various gene interaction ratios
revealed that the segregating population of cross 1 fitted to the ratio 12:3:1 for fruit
surface. The segregants of the cross 2, fitted for the ratio 3:1 for fruit shape at pedicel
attachment, 9:6:1 for fruit shape at blossom end and 9:3:4 for fruit surface character.
The chi-square analysis for leaf curl virus resistance revealed that the observed
ratio in the segregants holds a good fit to the ratio 3:1. The test results shows that the
genetics of resistance is governed by a single dominant gene in both the crosses.
Based on the yield and leaf curl virus incidence, the segregants C-2-161, C-2-168,
C-1- 117, C-2-10, C-2-154 and C-1-151 were found to be superior and are suitable for
further segregation studies.