The present investigation was carried during Kharif 2015-16 at Agricultural College Farm, Bapatla to estimate the combining ability and to determine the nature and magnitude of heterosis for yield and yield component traits in rice. The experimental material consisted of 21 hybrids produced by crossing three cytoplasmic male sterile lines with seven elite testers in Line x Tester design. The magnitude of combining ability revealed both additive and non-additive gene action were found to control the expression of the traits under study, however non-additive genetic variance was higher than the additive variance for all the studied traits except for test weight. Among parents, CMS line IR 58025A and testers NLR 33654, NLR 3083 were found to be promising good general combiners for grain yield plant-1 and other traits. Three crosses were found to be desirable for grain yield plant-1 where in the cross IR 58025A x NLR 33057 recorded significant sca effects for majority of the characters viz., days to 50% flowering, days to maturity, plant height, number of productive tillers plant-1, number of filled grains panicle-1 and grain yield plant-1.None of the hybrids recorded significant sca effects for all the eight characters.

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