Effects of Pruning Levels and Fertilizer Rates on Yield of Physic Nut (Jatropha curcas L.)

Abstract

Appropriate canopy management and proper application of fertilizer under different growing conditions and agronomic practices can obtain reliable yield of physic nut (Jatropha curcas L.). The objective of this study was to determine the effects of pruning level in first year and fertilizer rate of combined NPK in the first and second years on growth and yield of three-year old physic. A split plot design with four replications was used. Three pruning levels of 50, 75 and 90 cm from the ground were assigned in main plots and combinations of NPK fertilizers at the rates of 0, 312.5 and 625 kg ha-1 were arranged randomly in subplots. All pruning levels from the ground did not have significant effects on branch number and branch length (cm), whereas application of fertilizer did increase branch number and branch length especially at the rate of 312.5 kg ha-1. Harvest in the second year gave higher yield (1,559 kg ha-1) than did in the first year (1,180 kg ha-1) for all treatments, suggesting that it is not necessary to prune physic nut every year in commercial plantations. It is recommended to prune the three-year old physic nut at 70 cm from the ground. Pruning at 90 cm from the ground is possible but not at 50 cm. it is also recommended to apply fertilizer to the three-year old physic nut under rainfed conditions at the rate not exceeding 312.5 kg ha-1 and this should be based on soil analysis. Application of higher rates depressed yield