Genetic diversity in Jatropha (Jatropha curcas L.)

Jatropha (Jatropha curcas L.), an exotic non-edible oil seed bearing shrub and traditionally cultivated as a hedge plant, is widely considered as a potential feed stock crop for bio-diesel production in India. Low seed and oil productivity of the available Jatropha genotypes not only makes its cultivation uneconomical to the growers, but also renders unattractive to the bio-diesel industry. Genetic management is the only and the best sustainable option for enhancing seed and oil yielding potential of Jatropha given that Jatropha is being promoted for cultivation in marginal and waste lands. Considering that success of Jatropha genetic enhancement programmes hinges on the availability of diverse genetic resources, three-year old germplasm collected from southern Karnataka was evaluated during 2007 at the University of Agricultural Sciences, Bangalore for assessing genetic diversity among the accessions and classifying them into clusters for identifying genetically divergent accessions based on D-2 statistics for use in Jatropha breeding programmes. Results indicated substantial variability for most of the traits. The wide range of D-2 values and segregation of the accessions into as many as 12 clusters is a clear evidence for high degree of genetic divergence among Jatropha accessions. Ten out of 12 clusters contained one to four accessions indicating their uniqueness and substantial genetic divergence among them. Oil content followed by 100-seed weight and seed yield/plant contributed most in discriminating the accessions. It was suggested to select the representative accessions from the clusters having intermediate inter-cluster distance for use in hybrid development for harnessing maximum heterosis.