WATER REQUIREMENT OF POMEGRANATE (PUNICA GRANATUM L.) FOR SOLAPUR DISTRICT OF MAHARASHTRA STATE

Abstract

The study was carried out to select a best reference crop evapotranspiration model (ET(r)), developed crop coefficient (K(c)) and actual evapotranspiration of pomegranate (ET(c)) for Solapur (North latitude 17°10” to 18°32” and East longitude 74°42” to 76°15”) at 483.5 m asl in the semi-arid zone of Maharashtra. Six most commonly used reference crop evapotranspiration models were selected for testing their validity under the climatic conditions. The important reference evapotranspiration models are: (i) Penman-Monteith FAO-56 model, (ii) Modified Penman FAO-24 model, (iii) Hargreaves Samani model, (iv) FAO-24 Pan Evaporation model (v) Blaney Criddle model, and (vi) FAO Radiation model. For the estimation of shaded area at solar noon hour, a plywood board of 3.5×3.5 m size with grid marking of size 10×10 cm was used. Actual pomegranate evapotranspiration was determined by the crop coefficient approach where the effects of various weather conditions were incorporated into reference crop evapotranspiration and crop characteristics into crop coefficient. Testing of these models was done on the basis of the least root mean square error and regression analysis. Radiation method are higher followed by modified Penman method, Blanney Criddle, pan evaporation, Hargreaves-Samani and Penman Monteith. Out of six models the Hargreaves Samani method was found to least root mean square error under climatic conditions of Solapur region. The measured shaded area at solar noon increased from new leaf initiation to maturity of crop ranging from 0.68 to 10.80 m2 and decreased from harvesting period 10.80 to 7.43 m2. The water requirement of crop development and maturity period ranges from 32.85 to 65.75 L/tree/day. The crop coefficient values increased ranging from 0.15 to 1.20 from new leaf initiation to maturity period of the crop and the seasonal water requirement for the pomegranate crop during the kharif season varies from 9.6 to 65.75 L/tree/day. The present study is based on analysis of long term (25 years) climatic data and measured shaded area at solar noon of 5th year pomegranate orchards.