Heterosis and inbreeding depression for seed yield and its component characters in castor (Ricinus communis L.)

The experimental material consisting of 101 entries comprised of ten parents and their 45 hybrids and 45 F2s developed through half diallel mating design and one standard check (GCH 7) were evaluated in a randomized block design with three replications. The magnitude of standard heterosis in the positive direction was high for number of effective branches per plant and seed yield per plant; medium for 100-seed weight, effective length of primary raceme, length of primary raceme and low for oil content. Similarly, the magnitude of standard heterosis in the negative direction was high for number of nodes up to the primary raceme, plant height and medium for days to maturity of primary raceme and days to 50% flowering of primary raceme. The cross JI 368 x RG 2787 depicted significantly the highest and positive heterobeltiosis (51.08%), standard heterosis (40.15%) as well as the highest seed yield per plant (486.80 g). The crosses DPC 17 x SKI 343 and DPC 17 x JI 353 were the next best crosses exhibiting significant and positive heterobeltiosis (134.73% and 45.73%), standard heterosis (36.66% and 30.52%) and per se performance (474.67 g and 453.33 g). The range of inbreeding depression was from -37.45% (DPC 17 x SKI 215) to 34.18% (JI 372 x PCS 124) with a mean of 8.10%. Out of 45 crosses, none of the crosses showed significant positive inbreeding depression for seed yield per plant.