Combining ability and heterosis among elite bacterial blight resistant lines in rice (Oryza sativa L.)

Combining ability analysis for yield and other agronomic traits were made in F1 and F2 diallel of seven varieties resistant to bacterial blight of rice revealed highly significant combining ability variances for plant height, panicle number/plant, panicle length, spikelet number panicle-1, grain number panicle-1, total dry matter, harvest index and grain yield plant-1 indicating importance of non-additive gene action in their expression. The parent BJ 1 was the best combiner for most characters including yield. Parent BBL 307 and C 702015 were good combiners for days to flowering and spikelet and grain number/panicle. SCA effects indicted significant sea × generation interaction. The crosses C 702015 / IR 50400, BBL 307 / BJ 1, BBL 180 / C 702015 and RP 633 / RP 2151 recorded the highest sea effects for yield. Maximum value for relative and heterobeltiosis were 67.14 and 52.35 per cent, respectively. The above four crosses alongwith BBL 307 / BJ 1, BBL 307 / C 702015 and BBL 307 / IR 50400, BBL 180 / C 702015, C 702015 / IR 50400 and RP 633 / RP 2151 were identified as the best hybrids based on superior per se performance, heterosis and specific combining ability effects for exploiation.