LAUSR

ABSTRACT Apple is an important fruit tree in semi-arid and arid regions, but increasing water scarcity limits apple production. Earlier studies have reported that partial root-zone irrigation (PRI) can increase water use efficiency (WUE), but the effects of PRI on fruit quality and nutritional value are still less known. To close this knowledge gap, a two-year field experiment conducted to evaluate the effect of PRI treatments on biochemical properties, WUE, and stomatal leaf traits in the Red Delicious and Braeburn apple cultivars. The results showed that alternate partial root-zone irrigation (APRI75) and fixed partial root-zone irrigation (FPRI75) increased WUE by about 20–36% compared to control, respectively, but there was no significant difference in WUE between control and FPRI50. The highest antioxidant capacity, phenolic compounds, and phenylalanine ammonia-lyase (PAL) activity recorded in PRI treatments compared to control. In addition to improving the WUE and maintaining the yield, using APRI75 and FPRI75 to irrigate apple trees could be more effective in improving antioxidant capacity and phytochemical compounds such as anthocyanins and leading to increased nutritive value and quality of the apple fruits. Therefore, APRD75 and FPRD75 as potential water savings strategies might be suitable for irrigation apple trees under water scarcity.