MSc

The present study aimed to estimate the combining ability and gene action for yield and resistance to chilli thrips and yellow mite by line x tester analysis and to identify high yielding hybrids resistant to these pests. The research work was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2008-09.
Five susceptible high yielding chilli genotypes (lines) and three chilli thrips and mite tolerant chilli genotypes (testers) were crossed in a line x tester fashion to obtain 15 hybrid combinations.
The lines, testers and their hybrids were evaluated in replicated field trials for yield and resistance to chilli thrips and yellow mite. The yield trial observations were recorded for 13 characters viz., days to 50 per cent flowering, plant height, number of primary branches, number of secondary branches, plant canopy width, fruit bearing period, number of fruits per plant, fruit length, fruit girth, fruit weight, green fruit yield, crop duration and capsaicin content. ANOVA revealed that the genotypes were significantly different for all the characters. Combining ability analysis indicated that the characters number of secondary branches, fruit length, fruit girth, fruit weight and green fruit yield were governed by both additive and non additive gene action. Among them fruit girth and fruit weight showing preponderance to additive gene action while others showing preponderance to non additive gene action. The remaining characters viz., days to 50 per cent flowering, plant height, primary branches, plant canopy width, fruit bearing period, number of fruits per plant, crop duration and capsaicin content are mainly governed by non additive gene action.
Based on mean performance and gca effects, Vellayani Athulya was identified as the best general combiner among the lines and Bhaskar among the testers for yield and several yield contributing characters. The crosses, L1 x T3 and L5 x T2 were found to be promising chilli hybrids for yield and its component traits based on mean performance, sca effects and heterosis.
The resistance was based on population count and damage intensity to chilli thrips and yellow mite. Combining ability analysis revealed that number of thrips per leaf, number of yellow mites per leaf and damage intensity due to mite were governed by non additive gene action whereas thrips damage intensity was governed by both additive and non additive gene action with preponderance to additive gene action. Among lines, Anugraha and Ujwala were tolerant to both the pests whereas, Bhaskar and Kiran were highly tolerant among testers. Anugraha, Jwalasakhi and Bhaskar were found to be best general combiner for both thrips and mite resistance among the parents.
Considering both yield and resistance simultaneously, the hybrids L3 x T1 and L5 x T2 are high yielding and relatively resistant to chilli thrips and yellow mite respectively. These hybrids would hopefully yield desirable genotypes with high yield and resistance to chilli thrips or yellow mite in segregating generations. The hybrid L3 x T2 identified as relatively resistant to both chilli thrips and yellow mite was not remarkable with respect to yield.