The 2012 ASHS Annual Conference

Jatropha (Jatropha curcas L.) is a species in the Euphorbiaceae that has been identified as a potential bioenergy crop.  The seeds contain oil of high quality already proven suitable for biodiesel and jet fuel use.  However, jatropha is still non-domesticated. Breeding and genetic programs are limited. Key to any successful breeding program is the identification of genetic diversity. Efforts on introduction, collection, characterization, documentation, and preservation of genetic material are required. The evaluation of morphological and reproductive characteristics in previous studies with jatropha revealed a considerable amount of genetic variability that can be utilized to optimize characteristics directly related to yield. The objective of this study was to specifically evaluate the reproductive characteristics of 15 jatropha accessions in South Florida.  For each accession, plant sexuality, inflorescence type, flower initiation, total number of flowers per inflorescence, number of male and female flowers per inflorescence, male:female flower ratio, fruit initiation, total number of fruits, number of fruits per branch, fruit set, fruit fresh weight, fruit yield, seed ripening, total number of seeds, number of seeds per fruit, seed fresh weight, seed dry weight, seed yield, seed length, thickness and width,100-seed weight, and oil content were evaluated. Number of inflorescences and inflorescence set were evaluated for two flowering span periods, while remaining characteristics were evaluated during three different seasons; spring, summer, and fall. Data was submitted to analysis of variance and the phenotypic correlation between pairs of floral, fruit, and seed components was evaluated for all jatropha accessions.  Two flowering spans were identified throughout one year of evaluations, March through May, and August through November, respectively.  Seeds ripened within 90 days and a 3-month harvest period was identified for each flowering span.  There was significant variability among accessions for flowering characteristics, flowering spans and the interactions between them. The total number of flowers ranged from 68 to 225 for the first flowering span, and from 73 to 155 for the second flowering span. Maximum female flowers were 10 to 15, for the first and second flowering spans, respectively. Summer season favored female-type inflorescences, while Spring and Fall favored middle-type inflorescences.  Significant differences were also observed for number of fruits per bunch and fruit set between flowering spans.  Seed and oil characteristics also differed significantly.  Phenotypic correlations were significant for all traits. The variability found in this study for jatropha accessions if of high importance for germplasm selection and application in crop improvement programs.