In a context of severe water scarcity and high uncertainty of available irrigation water, the sustainable man-agement of irrigation inputs to the crop has become necessary. The main objective of the present study was to determine the mid-term effect of water restrictions using different plant water status indicators of yield and quality of flat peaches. Two treatments were tested: (i) control (CTL), irrigated at-100% of crop evapotrans-piration (ETc) during the entire season; and (ii) a regulated deficit irrigation (RDI) treatment, irrigated as the CTL, except during the second fruit growth stage (-70% ETc) and late post-harvest (-50% ETc), with the same fertilization as CTL. In the first and second water deficit periods, an average weekly reduction of 43 and 109 m3 ha-1 was achieved, respectively. This resulted in water savings of 33.6% in the RDI treatment with respect to well-irrigated trees and an increase in the irrigation water productivity of 45%, reaching values of around 4.16 kg m-3. Therefore, the optimization of irrigation water inputs in semi-arid conditions was achieved, by considering that the post-harvest period in this crop is a non-critical phenological period, with a stem water potential (& psi;s) threshold value of around-1.4 MPa. Multiple regression models were obtained as irrigation thresholds based on & psi;s for well-and deficit-irrigated trees.