Genetic dissection of heterosis and combining ability in castor (Ricinus communis. L)

The estimates of combining ability and nature of gene action were worked out by Line x Tester analysis (Kempthorne, 1957). The experimental material included 45 entries containing six pistillate lines (DPC 9, DPC 21, D PC 24, YRCP 1, YRCP 2 and JP 65), five monoecious lines (TMV 5, SKI 215, 48-1, M3/28-3-1, and JM 6), thirty cross combinations, and four standard checks (YRCH 1, YRCH 2, ICH 66, and YTP 1). Four hybrids (DPC 9 x M3/28-3-1, DPC 9 x TMV 5, JP 65 x M3/28-3-1 and JP 65 x 48-1) exhibited high and significant positive economic heterosis for seed yield. The combining ability analysis demonstrated that the mean sum of squares due to genotypes and crosses were significant for all yield and its contributing traits. The magnitude of genetic variances for 11 quantitative traits revealed the predominance of dominant gene action for all the traits except oil content and hundred seed weight. For most traits, testers contributed more to total variance than the lines and L x T interaction. DPC 9, DPC 24, TMV 5, and JP 65 were identified to be the best general combiners for seed yield and its yield components. The hybrids DPC 9 x M3/28-3-1, DPC 9 x TMV 5, JP 65 x M3/28-3-1, and JP 65 x 48-1 were the most effective specific combiners for seed yield and also exhibited significant and high standard heterosis in the desired direction for seed yield and majority of the yield contributing traits. Hence, these parents and cross combinations could be effectively utilized for development of high yielding castor hybrids