| Summary: | In this study, field experiments were conducted to investigate the effects of two water-saving practices—partial root-zone drying (PRD) and deficit irrigation (DI)—on potato growth and yield in comparison with full irrigation (FI). The required FI amount was applied to the potato plants to enable 100% crop evapotranspiration, and the plants received 70% and 50% of the irrigation amount of FI for DI (DI70 and DI50) and PRD (PRD70 and PRD50), respectively. The physiological characteristics of the potatoes during the 2014–2015 seasons indicated that the relative chlorophyll contents were not significantly higher for the DI and PRD treatments than for the FI treatment. The DI50 had the lowest net photosynthesis rate (<i>p</i> < 0.05) while DI50 and PRD50 had significantly lower stomatal conductance (g<sub>s</sub>) values in both years. Meanwhile, the values of the PRD treatments were lower than those of DI treatments based on the transpiration rates. The xylem (abscisic acid) based on PRD50 had an average increase of 0.38 mol/m<sup>2</sup> s due to decreasing g<sub>s</sub> values compared with other water-saving irrigation treatments. However, the FI and DI treatments had increased fresh tuber yields compared with the yields of PRD treatments. Furthermore, the PRD70 and PRD50 treatments significantly reduced the water productivity (WP) values by 30.16% and 41.32%, respectively, relative to that of FI.
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