Combining Ability and Heterosis of Rice

An experiment of six-parent half diallel analysis on rice (Oryza sativa L.) was conducted to evaluate the combining ability and heterosis for 14 yield and yield contributing characters. Seven Aus×Boro cross combinations were found with encouraging higher cross compatibility and BR21×BRRI Dhan28 was the most compatible combination. The analysis of variances indicating the genotypes differed for all the traits studied. The ratio of GCA and SCA variances for most of the characters revealed the predominance of additive gene action over non-additive. The combination BR21×BRRI Dhan29 showed desirable heterosis for days to 50% flowering, days to maturity, grain yield plant-1 and harvest index; BR21×BRRI Dhan36 for plant height, panicle length, and grain yield plant-1; BR24×BRRI Dhan29, BR26×BRRI Dhan29 and BR21×BRRI Dhan28 for days to maturity.; BR24×BRRI Dhan36 and BR26×BRRI Dhan36 for panicle length, secondary branch panicle-1, number of filled grain panicle-1 and grain yield plant-1;BR26×BRRI Dhan29 for panicle weight; BR24×BRRI Dhan36 for thousand grain weight. For grain yield plant-1 the cross BR26×BRRI Dhan36 was the best one followed by BR26×BRRI Dhan29.