Genetic associations, variability and diversity in seed characters, growth, reproductive phenology and yield in Jatropha curcas (L.) accessions

A thorough and extensive wild germplasm exploration survey was undertaken and 32 high yielding candidate plus trees (CPTs) of Jatropha curcas from different locations from a latitudinal and longitudinal spread between 12 degrees 41' and 22 degrees'E longitude and 77 degrees and 84 degrees 40'N latitude covering 11 locations in an area spread of 150,000 km(2) was collected for evaluating genetic association, and variability in seed and growth characters. Significant trait differences were observed in all the seed characters viz., seed morphology and oil content as were observed in growth characters viz., plant height, and female to male flower ratio and seed yield in the progeny trial. Broad sense heritability was high in general and exceeded 80% for all the seed traits studied. Female to male flower ratio showed near to 100% heritability followed by yield (83.61) and plant height (87.73). The path analysis revealed that female to male flower ratio had highest positive direct relationship with seed yield (0.789), followed by number of branches (0.612) and number of days from fruiting to maturity (0.431). Negative indirect effects were seen in number of days from flowering to fruiting which indirectly and negatively influenced yield through plant height and number of branches. Hierarchical clustering by Ward's minimum variance cluster analysis showed phylogeographic patterns of genetic diversity. K-means clustering revealed that trees from different geographic regions were grouped together in a cluster and as were trees from the same geographical area placed in different clusters suggesting that geographical diversity did not go hand in hand with genetic diversity. In addition clustering identified promising accession with favourable traits for future establishment of elite seedling seed orchard and clonal seed orchard for varietal and hybridization programmes.