EVAPOTRANSPIRATION AND CROP COEFFICIENT OF SWEET LIME UNDER DRIP IRRIGATION

This study was initiated to determine evapotranspiration (ET) and crop coefficient (K-c) of sweet lime and to establish the relationship bet ween ET and canopy to air temperature differential (T-c-T-a; degrees C ) under drip irrigation treatments with different amounts of water. Th e maximum value of K-c for sweet lime under drip irrigation (1.17) was greater than that for other citrus trees under irrigation systems oth er than drip irrigation (0.75). The maximum value of evapotranspiratio n to pan evaporation ratio (ET(p)/E(pan)) for sweet lime under drip ir rigation (0.71) was comparable with that of Valencia orange under drip irrigation in Arizona. The equation for estimation of average 24 h ET (mm day(-1)) by monitoring (T-c-T-a; degrees C) is ET = 3.02-0.94 (T- c-T-a). Furthermore, the equation for estimation of average 24 h ET, ( mm day(-1)) by monitoring (T-c-T-c) is ET-ET(p) = -0.43(T-c-T-c*) in which T-c is the canopy temperature of well watered trees (degrees C) .