Electronic Journal of Plant Breeding (Mar 2011)
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) crossesgenerated through half diallel and line x tester mating were subjected to combining ability analysis for various morphoagronomictraits. The analysis of variance for combining ability revealed that variance estimates due to sca were higher inmagnitude than the corresponding gca variances resulting in relatively higher non additive variance for most of the charactersexcept for days to 50% flowering, days to maturity and grain yield/plant. The genetic components of variance revealed relativelyhigher estimates due to dominance deviation than corresponding estimates of additive genetic variance for most of the charactersexcept for aforementioned characters. Average degree of dominance was in the range over dominance for most of the yieldcomponents and other traits, however maturity traits and grain yield/plant displayed partial dominance. None of the parents couldbe 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 xP5, 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 T2demonstrated desirable and significant sca effects. Hybridization of parents with good gca effects has an ample scope of throwingpromising transgressive segregants in the segregating generations to be used as commercial varieties. Similarly, crosscombinations with favourable sca effects and high per se performance, besides involving good combining parents can be handledthrough conventional breeding programmes. In addition, desirable characters across the two sub species can be combined toderive ideal genotypes for temperate agro ecosystems within an altitude range of 5000-7500 feet amsl.
