Fostering sustainable water use in almond (Prunus dulcis Mill.) orchards in a semiarid Mediterranean environment

This work examines the long-term effects of deficit-irrigation (DI) practices in almond crop (Prunus dulcis Mill.) in agronomical and physiological terms. The trial was conducted during four-year monitoring period (2014-2017), in an experimental orchard (SW Spain), subjected to three irrigation regimes; i) a full-irrigation treatment (F-I), which received 100% of crop evapotranspiration (ETC); ii) a regulated-deficit irrigation (RDI50), which received 50% of ETC during the kernel-filling period; and iii) a low-frequency deficit irrigation (LFDI), that was subjected to continuous periods of irrigation-restriction defined in terms of threshold values of leaf-water potential (psi(leaf)) during the kernel-filling period. During the water stress period, there were monitored psi(leaf), stomatal conductance (g(s)) and canopy temperature (T-C). Significant improvements in terms of water-use efficiency were found, as no differences in terms of yield between F-I and LFDI were found, leading to the conclusion that significant water savings (between 27 and 40%) can be achieved without compromising the yield. Moreover, threshold values of psi(leaf) and thermal indicators were defined which will allow establishing future irrigation scheduling without compromising almond yield, especially when DI strategies are being applied.