GENE ACTION AND COMBINING ABILITY FOR GRAIN YIELD AND YIELD RELATED TRAITS IN RICE (Oryza sativa L.)

Abstract

Line (five) × tester (two) analysis was conducted to determine good parents and the nature of gene action governing yield and its component traits in rice. The line × testers showed significant differences for all traits except for number of spikelets per panicle and hundred grain weight. Parents with low × high general combining ability (GCA) effects resulted in heterotic hybrid combination like the IR62829A/IR57301-158-1R. A low × low GCA gave the best heterotic combination i.e. IR68888A/’Sepidroud’. The study showed GCA to only identify better parental lots and it will be unwise to discard the low GCA types. Predominance of dominance gene action for all the traits studied except for flag leaf width and number of spikelets per panicle suggests heterosis breeding must be strongly pursued for exploitation of the yield advantage over the inbred varieties.