Combining ability study in rice (Oryza sativa L.) under temperate conditions of Kashmir

Abstract

Thirty intervarietal (15 indica x indica and 15 japonica x japonica) and fifteen inter-subspecific (indica x japonica) crosses generated through half diallel and line x tester mating were subjected to combining ability analysis for various morpho-agronomic traits. The analysis of variance for combining ability revealed that variance estimates due to sca were higher in magnitude than the corresponding gca variances resulting in relatively higher non additive variance for most of the characters except for days to 50% flowering, days to maturity and grain yield/plant. The genetic components of variance revealed relatively higher estimates due to dominance deviation than corresponding estimates of additive genetic variance for most of the characters except for aforementioned characters. Average degree of dominance was in the range over dominance for most of the yield components and other traits, however maturity traits and grain yield/plant displayed partial dominance. None of the parents could be identified to possess good gca effects for all the attributes, however the parents P1 (Jehlum), P3 (SR-1), P8 (K-332), P11 (Kohsar) and P12 (K-508) were found promising combiners for most of the traits. For grain yield/plant cross combinations P1 x P5, P1 x P2, P4 x P6, P8 x P11, P11 x P12 and for early maturity P4 x P6, P1 x P5, P1 x P2, P11 x P12 and L4 x T2 demonstrated desirable and significant sca effects. Hybridization of parents with good gca effects has an ample scope of throwing promising transgressive segregants in the segregating generations to be used as commercial varieties. Similarly, cross combinations with favourable sca effects and high per se performance, besides involving good combining parents can be handled through conventional breeding programmes. In addition, desirable characters across the two sub species can be combined to derive ideal genotypes for temperate agro ecosystems within an altitude range of 5000-7500 feet amsl.