Morphophysiological Traits as Indicators of Genetic Diversity in Brazilian Populations of Jatropha curcas L. Grown Under Water Deficit

Jatropha curcas L. (Euphorbiaceae) is a species grown in tropicalcountries and used for biodiesel production. Morphophysiological traits were analyzed to assess the genetic diversity in nine genotypes of J. curcas under deficit water. Seeds of plants from different populations, collected in diferente brazilian regions, were grown under two water regimes (100% and 50% tank capacity). Multivariate analysis was used to characterize genetic diversity. The UPGMA dendrogram built from the genetic distance group indicated the segregation of genotypes into five groups for growth traits and six groups for physiological traits. Then, an principal components analysis was carried out, to evaluate the pattern of character variations and then segregate the characteristics that could distinguish parental genotypes for use in plant breeding. Results showed 65.50% and 56.02% for the two first principal components of growth and physiological traits, respectively. Total root area was the most determining trait for genetic dissimilarity (18.9%) and group formation, followed by plant height (17.9%) and number of leaves (17.6%). On the other hand, stomatal conductance (gs) (24.9%) and guaiacol peroxidase (GPX) (20.9%) were the most determining physiological traits. The analysis of morphophysiological traits indicated CNPAE-298 and 299 as the most distant genotypes among the plant groups. Under water-limited conditions, total root area, plant height, gs and GPX were the most efficient traits to explain genetic dissimilarity among the genotypes, and for this reason they should be referred as a priority for further studies on genotypes selection in this species.