Gene Action and Combining Ability Studies Using CMS System for Developments of Hybrid Rice under Temperate Conditions

Abstract

Combining ability analysis was applied through Line x Tester analysis of 36 hybrids developed by crossing 18 lines (Males) with 2 CMS lines (Females) to learn the genetic architecture of various agro-morphological traits in rice for the development of hybrids under temperate conditions. Analysis of variance revealed significant differences among genotypes, crosses, lines, testers and line x tester interactions for all the traits studied. Preponderance of non-additive gene effects was realized by higher values of specific combining ability compared to general combining ability, ratio of variances of SCA to GCA and average degree of dominance. The proportional contribution of testers was observed to be lower than that of line x tester interactions, thus resulted in higher estimates of SCA variances. The estimates of GCA effects indicated male parent K-08-61-2 was a good general combiner for grain yield per plant and other yield contributing traits and among the female parent SKAU 11A was observed to be a good general combiner. Cross combinations SKAU 7A x K-08-61-2, SKAU 7A x SR-2, SKAU 11A x K08-60-2, SKAU 11A x K-08-59-3 and SKAU 11A x SKAU-389 were found to be good specific combinations for grain yield per plant and other desirable traits, and need to be tested on large scale.