Heterosis and Combining Ability Analysis for Yield and Related-Yield Traits in Hybrid Rice

Study of combining ability and heterosis were conducted on 12 F1 hybrids along with seven rice genotypes (threecytoplasmic male sterile lines and four restorer varieties) to know the pattern of inheritance of somemorphological traits for selecting superior genotypes. The experiment was carried out according to line x testermating design, during 2007-08. Analysis of variance revealed significant differences among genotypes, crosses,lines, testers and line x tester interactions for tiller number, plant height, days to 50% flowering, panicle length,number of spikelets per panicle, spikelet fertility and grain yield traits. Variances of SCA were higher than theGCA variances for traits except for plant height which indicated predominance of non-additive gene action in theinheritance of the traits. The highest heterosis (106.60%) was observed in cross IR68899A x Poya followed byother eight crosses for yield and most of its related traits. The proportional contribution of testers was observedto be higher than that of the interactions of line x tester that revealed the higher estimates of GCA variance that isadditive gene action among the testers used. Within CMS parents, IR62829A and among male parents, IR50 andPoya were observed to be good general combiners for most of the characters studied. The cross combinationsIR62829A x Mosa-tarom, IR68899A x Poya, IR58025A x IR50 and IR58025A x Poya were observed to be goodspecific cross combinations for grain yield and most of its related traits due to highly significant SCA andheterotic effects.