Physiological quality of Jatropha curcas L. seeds harvested at different development stages

Physic nut (Jatropha curcas) has great potential to be used as a source of biodiesel due its high content of oil. However, information on the production and seed technology of this species is rare, especially regarding the maturation process. The purpose of the work reported here was to evaluate the main changes during seed maturation, to characterize the physiological maturity and to define the ideal harvest time of Jatropha curcas seeds. During November and December, 2009, the female flowers from trees grown since 2006 were tagged at anthesis. The capsules (fruits) were harvested at 5-day intervals starting 35 days after anthesis (DAA) till 80 DAA and were classified as green, yellow or brown. Seed size, moisture content and dry matter, germination, first count (7d), speed of germination index and seedling growth were determined. The size of physic nut seeds increased until 50 DAA. The maximum seed quality, expressed in germination and vigour, and the maximum dry matter content that characterized physiological maturity, was attained 65 DAA when the fruits turned brown or brown with some yellow spots, and the seed moisture content was high.