A simple and alternative approach based on reference evapotranspiration and leaf area index for estimating tree transpiration in semi-arid regions

The present work aims to develop a simple approach relating normalized daily sap flow (liters per unit of leaf area) and daily reference evapotranspiration (ET0) (mm/day). Two methods (FAO-Penman-Monteith (FAO-PM) and Hargreaves-Samani (HARG)) of the calculation of ET0 were tested in order to examine their impact on the established relationships. The data sets used for developing this approach are taken over well irrigated orchards from three experimental sites (olive trees, cv. “Olea europaea L.”, olive trees, cv. “Arbequino” and citrus trees cv. “Clementine Afourar”) conducted in the Tensift region around Marrakech (center of Morocco) and one experimental site (pecan orchard, cv. “Carya illinoinensis, Wangenh. K. Koch”) conducted in the Yaqui Valley, northwest of Mexico).