Combining ability analysis of yield and yield components in selected rice (Oryza sativa L.) genotypes

This study was conducted to analyze the combining ability for yield and yield contributing traits of selected rice genotypes. Eighteen F2 populations developed by half-diallel mating design and seven parental lines were planted in randomized complete block design in three replications. Analysis of variance indicated that genotypes, general combining ability and specific combining ability mean square values were highly significant (p <= 0.001) for all measured traits which indicated the genetic diversity of the parents and the importance of both additive and nonadditive gene effects in the inheritance of the measured traits respectively. Parent P2 (WAC 18-WAT 15-3-1) followed by parent P1(WAB 1573-22-B-B-FKR 4-2-WAC 1-TGR 3-WAT9-1) were the best general combiners for days to flowering, number of effective tillers per hill, panicle length, flag leaf length and width, plant height, and grain yield per plant. Hybrid combinations with good mean performance, desirable SCA estimates and involving at least one of the parents with high GCA would be considered for favorable allele combinations. As a result cross combinations involving parent with good GCA (P2), WAC 18-WAT 15-3-1 x SR33701-HB3330-78 (2.54) had the high desirable grain yield followed by crosses, SR33701-HB3330-78 x SR33859-HB3324-93 (2.34), SR33701-HB3330-78 x SR33859-HB3324-133(2.43), and SR33859-HB3324-93 x SR33859-HB3324-133(1.48) which gave high SCA value in the required direction for grain yield. In general, the crosses showing significant and desirable combining ability effects were associated with betterper seperformance of their respective parents.