Genetic variability and association between characteristics in germplasm of the physic nut (Jatropha curcas L.)

The oilseed plant Jatropha (Jatropha curcas L.) has proven to be an important alternative for the production of biodiesel in Brazil. The aim was to understand genetic variability in the germplasm collection of UFRRJ as well as identify superior genotypes, carriers of important attributes for breeding. For this, 60 accessions of J. curcas, each of three years of age, were characterized based on 12 morpho-agronomic descriptors. This description showed that the characteristics for oil yield and canopy projection proved to have the most genetic variability, whereas intrinsic seed attributes showed the lowest variation. Correlation decay by path analysis, showed important associations between plant height, canopy projection, number of branches, time of fruit formation and oil content in the production of oil per plant. This result confirmed the possibility of such characteristics in the germplasm collection of UFRRJ being adopted as a basis for indirect selection in obtaining more productive genotypes of reduced size and shorter harvest season. Principal components analysis identified oil production and the number of branches as being the characteristics that most contributed to the observed variation. The clustering methods of Tocher and UPGMA generated seven and eight dissimilar genotype groups respectively, showing the possibility of their being involved in future crosses, and revealing considerable variability in the evaluated traits.