**2.4 Evapotranspiration (ETc)**

Evapotranspiration is the process by which an amount of water is used by any growth stage of a crop from sowing to harvest, at whatever time there is no water constraint in the soil [13, 16]. ETc is a function of leaf area (transpiring surface), because the bigger the leaf area (LAI), the higher ETc will be for the same atmospheric demand [17].
