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 between ET and canopy to air temperature differential ( T c − T a); °C) under drip irrigation treatments with different amounts of water. The maximum value of ( K c) for sweet lime under drip irrigation (1.17) was greater than that for other citrus trees under irrigation systems other than drip irrigation (0.75). The maximum value of evapotranspiration to pan evaporation ratio ( ET p E pan ) for sweet lime under drip irrigation (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 °C) is ET=3.02−0.94 ( T c − T a). Furthermore, the equation for estimation of average 24 h ET, (mm day t−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 (°C).