.

The study was designed to examine the actual evapotranspiration and crop coefficient (Kc) of eight months old
Jatropha curcas grown in mini-drainage lysimeter with a cylindrical drum of circular cross-sectional area of 0.246
m2, diameter 0.56 m and 1.0 m depth. Investigation was conducted with drip irrigation system using five mini
lysimeters. Each lysimeter contained one pressure compensating emitter of 4L/hr. Climatic variables were obtained
for the determination of reference evapotranspiration (ETo) using the FAO-Penman Monteith model. The value for
the crop evapotranspiration (ETc) was determined from the lysimeter using the soil water balance method on daily
basis and the crop factor (Kc) was estimated from the ratio of ETc / ETo. The ETo estimated from weather data for the
crop growing season ranged from 19.3 to 33.1 mm/day. The average crop coefficient (Kc) values at different growth
stages were 0.6, 0.9, 1.2 and 0.8 for the initial, development, mid-season and late season respectively. The research
output will enhance the productivity of farmers with optimum water management on large scale Jatropha
cultivation.