Improving Almond Productivity under Deficit Irrigation in Semiarid Zones

Sustainable water use is one of the greatest challenges of irrigated agricultural systems. This study presents the results related to the agronomic and physiological response to the deficit irrigation of almond trees (Prunus dulcis DA Webb Mill cv. Guara) under semiarid Mediterranean conditions in the Guadalquivir river basin (SW Spain). Two deficitirrigation strategies were tested: i) regulated deficit irrigation (RDI), which was irrigated at 100% of crop evapotranspiration (ETC) throughout the irrigation period, except during the kernel-filling stage, when these trees where irrigated at 30% ETC, and ii) low-frequency deficit irrigation (LFDI), in which trees were subjected to different irrigationrestriction periods, defined in terms of stem water potential at midday (ΨStem). As control, a fully irrigated treatment (C100) was used, which received irrigation covering the 100% of ETC. The stem water potential (ΨStem), the stomatal conductance (gS), the photosynthesis rate (Pn) and canopy temperature (TC) were monitored, revealing significant differences mainly in LFDI in comparison with C-100. Also, highly significant relationships were found among plant physiological parameters, showing that the water status is strongly related to the crop water availability. On other hand, in terms of nut yield, there was a notable improvement under LFDI compared with RDI, with increases of 16% in relation to C-100, and with water savings of close to 170 mm. Thus, these findings demonstrate that the LFDI is a sustainable strategy to improve almond productivity as well as water-use efficiency under limited water resources.