Variation in seed production of Jatropha curcas L. accessions under tropical dry forest conditions in Ecuador

The Ecuadorian Government has, since the end of 2011, promoted an initiative for using pure jatropha oil, derived from the seeds of Jatropha curcas L., to generate electricity to supply Floreana Island (one of the Galapagos Islands). In the present study, nine elite accessions of J. curcas from tropical dry forests in Ecuador were cultivated for the purpose of evaluating seed production in relation to the propagation method used (seed, cutting). A split-plot design with three replicates was applied. Seed production, measured over a period of 7 years (2009-2015) showed a large year-to-year variation. However, seed production varied significantly among accessions and depended on the propagation method (seeds or cuttings). Propagation by stem cuttings stabilized the variability in the vegetative and seed production components measured, increasing the strength of their relationships with seed yield. The three highest yielding accessions produced 0.28-0.30 kg of seeds tree(-1) year(-1). As seed yield was not correlated with annual precipitation, the year-to-year variation in production of accessions indicates the effect of other factors not considered here, such as agronomic practices. The study findings suggest that agroforestry practices could be developed that would enable J. curcas to play a predominant role in a strategy for tropical dry forests aimed at reducing poverty (also known as pro-poor growth strategy).