Studies on Combining Ability and Gene Action for Seed Yield and Architectural Traits in Castor (Ricinus communis L.)

The analysis of variance for combining ability revealed that mean square values due to both parents and hybrids were significant for all the characters suggesting an importance of both additive and non-additive gene effects for the inheritance of studied characters. However, potence ratio and predictability ratio showed prime importance of additive gene effect for the characters viz., days to 50 % flowering of primary raceme, plant height up to primary raceme, number of nodes up to primary raceme, number of effective branches per plant, length of primary raceme, effective length of primary raceme, number of capsules on primary raceme, number of secondary spikes per plant, total number of capsules per plant, test weight of 100 kernels, kernel length, kernel width, seed yield per plant and oil content; while, non-additive gene action was preponded for volume weight. Whereas, for the characters viz., number of tertiary spikes per plant, days to 50% maturity of primary raceme and shelling out turn, the value of predictability ratio was close to one half indicating importance of both additive and non additive gene effects. In respect to gca effect of parents, the results revealed that for seed yield per plant, parents namely ANDCI 10-12, ANDCI 8, ANDCI 10-4 and ANDCI 10-3 were good general combiners. These inbreds were also good general combiners for length of primary raceme, effective length of primary raceme, total number of capsules on primary raceme and total number of capsules per plant. Among the crosses, crosses namely ANDCI 10-1 x ANDCI 9, ANDCI 10-12 x ANDCI 10-11, ANDCI 8 x ANDCI 10-3 and ANDCI 8 x ANDCI 10-11 which depicted significant and positive sca effect for seed yield and its contributing traits. In general the hybrids, which exhibited high sca effect, did not always involve both good general combiner parents with high gca effect, there by suggesting importance of both intra and inter-allelic interactions. These cross combinations could be utilized for further use in breeding programme for amelioration of seed yield and other desirable characters in castor.