Evapotranspiration and crop coefficients of drip-irrigated apricot trees under semiarid climatic conditions

This study was conducted to determine the evapotranspiration and the most suitable crop coefficients of drip-irrigated Salak apricot (Prunus armeniaca, L., cv. Salak). Application of irrigation water (I) was based on cumulative class A pan evaporation (Epan) within the irrigation intervals. Actual evapotranspiration (ETc) of apricot was calculated according to the water balance method. ETc was determined as 596 mm during the experimental period (May-September). Reference evapotranspiration (ETo) was calculated with FAO Penman-Monteith equation. There were also significant relationships among I, Epan, ETc and ETo (p<0.001-0.05). Crop coefficients (Kc) ranged from 0.56 to 0.96 (0.89 for May, 0.96 for June, 0.95 for July and August and 0.56 for September). Kc values calculated on the basis of the water balance over a 5-month-period led to a saving of 19.4% water, since the coefficients were slightly below those presented in the FAO 24. Thus, using the relationship between ETc and Epan or Kc values obtained from present study is recommended for irrigation scheduling of Salak apricot.