Basal crop coefficients for early-season peach trees

A 4-year long experiment was conducted using drainage lysimeters to determine the basal crop coefficients of an early season drip irrigated peach tree cultivar growing in a clay loam textured soil in southern Spain. The lysimeters were equipped with irrigation and drainage water meters and access tubes for monitoring the soil water content by neutron probe. Crop evapotranspiration (ETc) was obtained from the water balance equation. Following the dual crop coefficient approach, Kc was split into the basal crop coefficient (Kcb) and the soil evaporation coefficient (Ke). The effect of tree size on Kcb was determined for two canopy covers. The Kcb for full yield peach trees changed during the growing season gradually increasing from 0.15 at the beginning of the year (January) to a maximum of 1.0 during July, followed by a rapid fall to 0.15 at the end of year. The proposed curvilinear Kcb pattern fitted well with the phenological stages and their water use, and could serve for irrigation scheduling for early maturing peach trees growing in Mediterranean semi-arid climatic conditions.