Abstract

                                Combining ability and heterosis studies were conducted on 52 hybrids developed from crossing four cytoplasmic male sterile lines with 13 restorers in a line x tester fashion. The magnitude of sca variance was higher than gca variance for all the characters indicating the predominance of non- additive gene action. Among the parental lines and testers, APMS 9A MTU II-110-9-1-1-1-1, MTU II-283-7-1-1, MTU II-143-26-2 and MTU 1071 were good general combiners for grain yield and yield component characters. Better heterotic combiners based on per se performance, significant sca effects and standard heterosis for grain yield per plant were APMS 9A x MTU II-143-26-2, APMS 6A x MTU II-110-9-1-1-1-1, APMS 10A x MTU II-283-7-1-1 and IR 58025A x MTU II-190-1-1-1-1-1.

Key words : Cytoplasmic male sterility, General combining ability, Specific combining ability, rice hybrids.