Genetic analysis of heterosis for yield and yield components in inter-subspecific (indica/japonica) crosses in rice (Oryza sativa L.)

Twenty five rice hybrids involving five Indica CMS lines and five Indlca-Japonlca derivative restorers were evaluated for nine quantitative traits to elucidate the nature of gene action involved in the inheritance of Important quantitative traits. Further, It would facilitate the selection of parents with good gca and inter-subspeclflc crosses with good sea effects.. The estimates of variance components revealed the predominance of sca variance in relation to gca variance for all the traits studied except days to 50% flowering and plant height indicating that the traits were predominantly under the control of non-additive gene action. The lines IR58025 A and APMS 6A were found to be good general combiners as they could contribute alleles with positive effect for Improving all the Important quantitative traits. Among the testers, C-54 and PA-29 were proved to be good general combiners for majority of the yield contributing traits. Among the 25 inter sub-specific cross combinations, six hybrids viz., IR 58025A1 IR 65598-112, IR 58025A1 BCW 56, IR 69628A1 PA-29, PMS-10A1 C-54, APMS6A1C-54 and APMS 6A1 IR 68516-3 were found to be good having maximum standard heterosis of 36% for grain yield. These crosses were found to involve at least one parent with high gca and other parents having high, average or low gca effects indicating the involvement of additive as well as non-additive genetic interactions operating in these crosses.