Phd

The investigation entitled “Development of chilli (Capsicum annuum L.) hybrids with leaf curl virus resistance, high yield and quality” was carried out at the Department of Vegetable Science, College of Agriculture, Vellayani, during the period of 2015-2018. The study was aimed at identification of sources for chilli leaf curl virus (ChiLCV) resistance, development of chilli hybrids with ChiLCV resistance, high yield and quality and studying the gene action of ChiLCV resistance.
The investigation was conducted in four experiments. In experiment I (a), 70 chilli genotypes were evaluated for yield and quality traits. The best genotypes based on per se performance were CHIVAR-9 for plant height (73.33 cm), CHIVAR-4 for primary branches plant-1 (4.77), Jwalasakhi for days to first harvest (42.00 days), CHIVAR-7 for fruits plant-1(137.33), Vellayani Athulya for days to first flower (26.94 days), fruit length (8.50 cm), fruit girth (4.78 cm) and fruit weight (7.57 g), CA-32 for yield plant-1 and yield plot-1 (587.33 g and 16.10 kg/6.48m2 respectively), Punjab Sindhuri for vitamin C (120.33 mg 100 g-1) and Byadagi Kaddi for carotenoids (331.33 mg 100 g-1). Seven genotypes viz., CHIVAR-3 (L1), CHIVAR-7 (L2), CHIVAR-6 (L3),
CA-32 (L4), Vellayani Athulya (L5), Keerthi (L6) and CHIVAR-10 (L7) were selected based on selection index ranking for utilization as lines in line (L) × tester (T) analysis.
Among the 70 genotypes screened against ChiLCV under field condition [experiment I (b)], 23 were moderately susceptible, 12 each were susceptible and moderately resistant, ten were symptomless, six were resistant, five were highly resistant and two were highly susceptible. The selected ten symptomless and five highly resistant genotypes were subjected to artificial screening by using whitefly mediated and graft inoculations in experiment II (a). Six genotypes were symptomless under whitefly mediated inoculation, among which, four genotypes viz., Sel-3, Sel-4, Sel-6 and CHIVAR-1 showed highly resistant reaction under graft inoculation.


The resistant genotypes identified under artificial inoculation by Polymerase Chain Reaction (PCR) using universal primers (AV494/AC1048) for the confirmation of ChiLCV.
All the graft inoculated genotypes showed presence of virus. However, in the whitefly mediated inoculation, four genotypes viz., Sel-3 (T1), Sel-4 (T2), Sel-6 (T3) and CHIVAR-1 (T4) did not show any amplification for presence of virus. Hence, they were used as testers (male parent) in line (L) × tester (T) analysis. The overall disease score was higher with graft inoculation than whitefly mediated inoculation. The BLAST analysis of the amplified sequence showed 93 per cent similarity to Tomato leaf curl Karnataka virus (ToLCKV).
Seven genotypes (lines) with high yield and quality attributes were crossed with four highly resistant genotypes (testers) in line (L) × tester (T) mating design in experiment III (a) to produce 28 F1 hybrids. These hybrids were evaluated along with parents and two checks (CH-27 and Arka Harita) for yield and quality attributes and ChiLCV resistance during summer in 2017 [experiment III (b)].
Based on per se performance most promising hybrids were L3 × T2, L6 × T1, L1 × T1, L7 × T1 and L3 × T1 for yield traits and L4 × T1, L4 × T2, L4 × T3 and L7 × T1 for quality traits. The superior crosses based on heterobeltosis, standard heterosis and SCA effects were L3 × T2, L1 × T1, L7 × T1, L6 × T1, L3 × T1, L2 × T4, L4 × T1, L5 × T3 and L5 × T4 for yield attributes; L4 × T1, L4 × T2, L3 × T1, L7 × T1, L3 × T2, L6 × T3 and L1 × T1 for quality traits; L6
× T1, L7 × T4, L3 × T2, L7 × T1 and L7 × T3 for ChiLCV resistance.
Lines vs. testers showed significant differences for all the characters except for plant height. The GCA effects for testers were significant for all the traits except for days to first harvest. The ratio of σ2GCA/σ2SCA was less than unity for all the characters, which indicated the predominance of non-additive gene effects in the inheritance of these traits. The contribution of lines were more compared to testers for all the characters except for primary branches plant-1. The superior lines based on GCA effects were L1, L3, L7 and L6 for yield attributes; L2, L3, L4 and L7 for quality traits and L1, L2 and L4 for


ChiLCV resistance. Among testers, T1 and T2 were best general combiners for yield and quality traits, and T1 and T3 for ChiLCV resistance.
The hybrids viz., L3 × T2, L7 × T1, L1 × T1, L6 × T3, L1 × T4, L4 × T2,
L5 × T3, L5 × T4, L7 × T3 were most promising with desirable SCA effects, heterosis and per se performance for yield and quality attributes and they were moderately resistant to ChiLCV except L5 × T3 and L5 × T4. The hybrid L1 × T1 and L7 × T1 had both parents with high GCA effects for yield plant-1. All the four testers were symptomless and among seven lines, two were moderately resistant and five were moderately susceptible. Among 28 F1 hybrids, 12 showed moderate resistant reaction, 11 were moderately susceptible and five susceptible. The check hybrids CH-27 and Arka Harita were moderately resistant and susceptible respectively.
Three superior crosses identified from line (L) × tester (T) analysis viz., cross 1 (L1 × T1), cross 2 (L3 × T2) and cross 3 (L7 × T1) were utilized for generation mean analysis. The six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were developed and evaluated during 2018 summer. Both simple and joint scaling tests were significant for all the characters in all the crosses indicating the inadequacy of additive-dominance model and involvement of digenic or higher order non-allelic gene interactions.
Duplicate type of epistasis was observed for plant height, days to first flower, days to first harvest, fruit length, fruit girth, vitamin C, carotenoids and ChiLCV resistance (cross 1); plant height, primary branches plant-1, days to first harvest, fruit girth, fruit weight, fruits plant-1, vitamin C, carotenoids and ChiLCV resistance (cross 2); primary branches plant-1, days to first flower, days to first harvest, fruit girth, fruit weight, fruits plant-1, yield plant-1, vitamin C, carotenoids and ChiLCV resistance (cross 3). These crosses can be improved by biparental mating between recombinants in early segregating generation and delaying the selection in the advanced generations.
Complementary type of epistasis was noticed for fruits plant-1, yield plant-1 and yield plot-1 (cross 1); fruit length, yield plant-1 and yield plot-1 (cross 2); plant height and yield plot-1 (cross 3). Additive, additive × additive or complementary gene interactions are fixable, thus, these crosses can be


exploited effectively through pedigree method of selection. For ChiLCV resistance dominance (h) gene action, additive × additive (i), additive × dominance (j) and dominance × dominance (l) type of gene interactions are significant. Among them, the former three are in negative desirable direction.
The four ChiLCV resistant genotypes identified in this study could be used as potential parents for ChiLCV resistance breeding programme. The 93 per cent similarity of the amplified sequence to ToLCKV suggests that, it could be a strain of ToLCKV responsible for ChiLCV disease. The parents L1, L3, T1 and T3 were superior on the basis of GCA effects for most of the economic traits studied. The hybrids L3 × T2, L7 × T1, L1 × T1, L6 × T3, L1 × T4, L4 × T2 and L7 × T3 were most promising for yield and quality traits, and were moderately resistant to ChiLCV. The dominance (h) gene action and dominance
× dominance (l) epistasis were predominant for yield and quality traits indicating the importance of heterosis breeding in varietal improvement of chilli. The ChiLCV resistance could be improved through recombinant breeding or recurrent selection.