Study of gene action and heterosis in monostem/shybranching genotypes in sesame (Sesamum indicum L.)

Abstract

Eleven genotypes consisting of five lines (branched genotypes) and six testers (monostem genotypes) were crossed in a line x tester mating design. The resulting thirty hybrids were evaluated for general and specific combining ability, variance components and heterosis. The sca variance was greater than the gca variance for the traits days to 50 percent flowering, days to maturity, number of capsules, capsule length, number of seeds per capsule, 100-seed weight, seed yield per plant and oil content suggesting that these characters were governed predominantly by non-additive components. The GCA variances were predominant in plant height and number of branches, indicating that these characters were by and large governed by additive component of heritable variance. The line TMV3 showed high gca for seed yield, days to 50 percent flowering, days to maturity, plant height, number of capsules and oil content while the tester, KS 990812 recorded “significantly high gca effect for number of capsules. The specific combining ability effects showed that out of thirty hybrids, four hybrids viz., CO 1 x Cordebergea, Paiyur 1 x KS 99153, TMV 4 x MT 34 and TMV 5 x KS 99037 showed significant positive sea effect for single plant yield. Regarding the branching characters all the thirty hybrids registered favourable sea effects. Heterosis was worked out over mid parent, better parent and standard parent CO1. The cross Paiyur1 x Cordebergea was early in flowering and duration, while the cross TMV5 x Cordebergea was having superior heterosis for monostem / shybranching nature with desirable seed yield per plant. TMV3 x KS 990813 was superior for number of capsules per plant and seed yield per plant. Paiyur Ix MT34 showed good performance for number of seeds per capsule and oil content with desirable heterosis for seed yield per plant. These superior crosses can be utilized for hybrid development.