Vol. 2, Issue 2, Part G (2016)

Abstract
An experiment of line x tester mating design was conducted to study the nature and magnitude of gene action i.e. general combining ability (GCA) and specific combining ability (SCA) of 12 yield and yield contributing characters. The experiment was conducted with 10 rice genotypes and 25 F1s at the experiment field of SAU during June 2013 to June 2014. Highly significant differences for genotypes and lines were observed which revealed the wide range of variability among the genotypes and lines studied. The SCA variances were found significant for most of the characters. Higher ratio of SCA and GCA variances indicating preponderance of non-additive gene actions in the inheritance of all the characters except filled spikelet per panicle. The contribution of either lines or testers was observed to be higher than that of the interactions of line x tester. Such results revealed the higher estimates of GCA variances i. e. additive gene action but in case of 1000 grain weight, days to flowering and grain yield per hill higher estimates of SCA variance i.e. non-additive gene action were found. Among the male parents, SAU509R and SAU525R were observed to be good general combiner for most of the character studied. Cross combinations, IR62829A x SAU509R. IR62829A x SAU523R, Jin23A x SAU507R, Dakshahi A x SAU525R and Luhagura A x SAU523R were observed to be good specific cross combinations for magnitude of gene action.