Phenotypic Diversity of Jatropha curcas L. Accessions under Warm Subtropical Conditions

The phenotypic diversity of 15 accessions of jatropha (Jatropha curcas L.) during the first and second flowering periods under the warm subtropical south Florida climate was assessed by using multivariate analysis.  Plants were established in field plots at the Tropical Research and Education Center (TREC), University of Florida, in Homestead, FL.  Principal Component Analysis (PCA), cluster analysis, and phenotypic correlations between pairs of characters were estimated. A total of 180 jatropha inflorescences were tagged to evaluate the type of inflorescence. Inflorescences were subdivided into three types: female-type, male-type, and middle-type. A higher number of female-type inflorescences was observed during the summer.  Field evaluations using 15 quantitative traits showed significant variation among accessions.  The oil content ranged from 19.30% for TREC 45 to 35.62% for TREC 31.  Seed dry weight had positive correlation with seed fresh weight, seed length, seed thickness, seed width, and 100-seed weight, and negative correlation with oil content. Based on the variations across the 15 morphological traits in the first and second flowering periods, the Average Linkage-Unweighted Pair Group Method with Arithmetic Mean (UPGMA) clustering mechanism divided all 15 jatropha accessions into five different clusters.  The PCA reduced the collected data to three principal components that cumulatively explained 73.5% of the total variance observed.  Based on UPGMA cluster and PCA assessments, accessions can be evaluated in the first period of flowering, corresponding to Spring.  In addition, phenotypic characteristics, such as seed dry weight, 100-seed weight, total flowers per inflorescence, male flowers per inflorescence, and fruit set can be used to distinguish accessions.  Accessions TREC 31 and TREC 55 had superior averages for almost all characters evaluated and could be likely used as parents in future breeding programs.