Crop coefficients for prediction of evapotranspiration and irrigation requirements of drip irrigated castor (Ricinus communis L.)

A study was conducted on castor (Ricinus communis L.) in winter 2009-10 at Agricultural College Farm, Rajendranagar, Hyderabad with different drip irrigation schedules at 40, 60 and 80% pan evaporation replenishment levels either kept constant throughout the crop life or combinations at vegetative, flowering and development stages were compared with surface check basin method, irrigated at 0.8 IW/CPE ratio to derive crop coefficients (Kc) for drip irrigated castor. The Kc values were also used to suggest methodology for determination of periodic and peak irrigation requirements of castor for field application. The Kc values worked out varied between 0.345 to 0.822 and the average Kc values for different phenological phases of germination and establishment, vegetative, flowering, capsule development,seed filling and maturity periods were 0.449, 0.626,0.771, 0.940, 0.677 and 0.38, respectively. The peak irrigation, net irrigation and gross irrigation water requirements worked out were 808.7 m , 32.11cm and 33567.4 m , respectively for drip irrigated castor.