COMBINING ABILITY IN RELATION TO HETEROSIS FOR QUANTITATIVE CHARACTERS IN SUGARCANE

Abstract

Genetic variances were estimated by full-sib and half-sib analysis in sugarcane among the 30 FIS involving 10 female lines and 3 testers. Variances due to lines were significant for stalk height, stalk girth, and stalk weight, whereas variance due to testers was significant only for stalk density. Variances due lines x testers were significant for stalk height and stalk girth. σ2A/σ2D showed the predominant role of nonadditive gene action in the inheritance of No. of miIlable canes/stool, stalk height, stalk girth and stalk density, and additive gene action for stalk weight and stool weight. The degree of dominance was in the range of overdominance for No. of miIlable canes/stool, stalk height, stalk girth and stalk density. Lines contributedmaximum tovariances due to hybrids foraH the characters except stalk density. On the basis of per se performance and gca effects, CoS 8210, Sea 271/78 and CoS 7931 were good general combiners for stool weight. On the basis of per se performance and sea effects and heterotic response, the crosses Sh 670179 x Sea 4/79, Pl1598 x Sea 4/79, Sea 271/78 x CoS 7931 and UPl x CoS 758 were best specific combinations for stool weight.