Irrigation history and pruning effect on growth and yield of jatropha on a plantation in southeastern Brazil

Jatropha is an oilseed culture that has been highlighted due some specific agronomic aspects. This plant produces high oil quantities in its seeds that is used for biodiesel production. One of the major challenges regarding to the Jatropha cultivation is the lack of information on many management techniques, especially the irrigation and pruning management in adult plants in southeastern Brazil. The objective of this study was to study the combined effect of irrigation history and different pruning on Jatropha plant growth and yield. The experiment was conducted during the 4th year of Jatropha growing season at University of Sao Paulo experimental area in Piracicaba, Brazil. The experiment was arranged in randomized block with four replications and treatments were considered the pruning type: No pruning (P1), pruning at 1.5 m high and 2 m canopy diameter (P2), pruning at 2 m high and 2 m canopy diameter (P3). In addition, two water conditions were also evaluated: Irrigated (I) and rainfed conditions (R). Plant growth (height and canopy diameter) and leaf area index (LAI) were evaluated monthly and productive variables were determined at the end of the experiment. Irrigation history influenced canopy diameter, absolute growth rates for plant height and canopy diameter, the relative growth rate for canopy diameter, and all productive variables. Pruning provided differences in all growth variables, where P2 presented the highest average on plant growth rates. The plants under irrigation history conditions showed the highest yield.   Key words: Jatropha curcas L., oilseeds, center pivot, water management, biofuels.