Combining ability studies using different CMS sources in rice

Combining ability analysis was carried out involving 125 crosses for grain yield, its components and some of the quality characters in Line x Tester crosses. The magnitudes of specific combining ability (SCA) variances were higher than the general combining ability (GCA) variances for all the characters except productive tillers plant⁻¹ which indicated preponderance of non-additive gene action in the inheritance of these traits. The SCA variances were significant for all the characters except days to 50% flowering, head rice recovery, 1000-grain weight, kernel length, kernel L: B ratio, protein content (%) and amylose content (%). Among females, RTN3B and RTN-2B and among males IR-63879-195-195-2-2-3-2, NVSR-20, BL-184AR, GR-7 and IR-8866 were observed to be good general combiner for yield and most of the yield contributing characters. The cross combinations, RTN-3A X BL-184AR, RTN-13A X GR-7 and RTN-2A X NVSR-20 crosses exhibited positive significance SCA effects for grain yield plant⁻¹and some associated characters. Among these, RTN-3A X BL184AR was found to be the best combination involving good x good general combiner parents and also exhibited significant highest SCA effects, significant heterobeltiosis and standard heterosis for grain yield plant⁻¹.