Abstract
Six parents of Jatropha curcas were crossed in half diallel fashion, and the F 1s were evaluated to determine the combining ability for nine germination parameters. The ratio between general combining ability (GCA) and specific combining ability (SCA) variances indicated preponderance of additive gene action for all the characters except germination percentage, time of 50% germination, seedling length, and seedling vigor index. The parents P 1 and P 2 were the best general combiner for most of the characters studied. The cross P 1 × P 5 was the best specific combiner for speed of emergence, germination percentage, germination energy, germination index, and seedling vigor index, the cross P 2 × P 5 for mean germination time, time of 50% germination, and seedling length, and the cross P 4 × P 5 for number of days to first germination. The germination percentage varied from 58.06 to 92.76% among the parents and 53.43 to 98.96% among the hybrids. The highest germination (98.96%) was observed in hybrid P 2 × P 4, and none of the hybrids or parents showed 100% germination. The highest germination index (GI) and seedling vigor index (SVI) were found in hybrid P 1 × P 5 and P 2 × P 5, respectively. The results of this study provide clue for the improvement of Jatropha variety through breeding program.
Highlights
Physic nut (Jatropha curcas L., family of Euphorbiaceae) is a common oil seed plant, its seeds contain about 30% of inedible oil, can be found in most tropical and subtropical countries of the world, and can grow up to 5 m height [1]
The analysis of variance revealed highly significant (P < 0.01) differences among the parents and their hybrids for all the germination traits indicating the existence of wider variability among the parental genotypes and the hybrids of J. curcas
The general combining ability (GCA) and specific combining ability (SCA) variances were highly significant for all germination traits (Table 1)
Summary
Physic nut (Jatropha curcas L., family of Euphorbiaceae) is a common oil seed plant, its seeds contain about 30% of inedible oil, can be found in most tropical and subtropical countries of the world, and can grow up to 5 m height [1]. Jatropha curcas is a multipurpose biodiesel plant adaptable to a wide range of edaphic and climatic conditions [3]. It is propagated by both generative (direct seeding) and vegetative (stem cuttings) techniques [1, 3,4,5], but plants propagated from stem cuttings do not develop a taproot. Genetic and environmental factors determine germination rate, speed of germination, and vigor of seed and seedling [8]. Speed of germination is genetically correlated to seed dormancy. Selection for quick germination was unsuccessful, and differences between genotypes were regulated by maternal tissue of seed ball [10]
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