The seeds of 6 × 6 half diallel progenies of Jatropha curcas were used to evaluate the effects of genotypes (parents and their hybrids) on germination traits of jatropha at Universiti Kebangsaan Malaysia. Germination traits were varied significantly (p<0.01) among the seeds of hybrids and their parents. The germination was started at four days after planting and prolonged until 15 days. Seed germination varied from 58.06 to 92.76% among the parents and 53.43 to 98.96% among the hybrids. The highest germination was observed in the hybrid P2 × P4 and none of the hybrid or parent showed complete (100%) germination. The maximum GI (germination index) and SVI (seedling vigour index) were found in the hybrids P1 × P5 and P1 × P2 and the lowest in P2 × P4 and P3 × P6, respectively. For most germination parameters parents behaved poorly than that of the hybrids.
Six parents (P1, P2, P3, P4, P5 and P6) half diallel population of Jatropha curcas were evaluated to determine the combining ability, genetic components of variance and heterosis for yield contributing traits. Diallel analysis showed that both additive and dominance gene action was responsible for the genetic regulation of all the traits under study. The cross combination P1 × P3 showed the highest positive specific combining ability for seed yield per plant. Combining ability results were also in close agreement with the findings of estimate of genetic components of variance. The seeds per fruit (89%) and 100-seed weight (93%) showed maximum narrow sense heritability. Seed yield per plant showed high mid parent (254.13%) and better parent (202.36%) heterosis in the cross combinations of P2 × P5 and P1 × P3, respectively.The parents of P1, P2, P3 and P5 were found to be superior for seed yield components when used in cross. Considering seed production for each plant, the hybrids P1 × P2, P1 × P3, P2 × P5 and P4 × P6 could be selected for the development of hybrid varieties.