Drought duration alters the soil water threshold corresponding to the leaf photosynthetic efficiency of potato in semi-arid regions

Moderate to severe water deficits due to drought in irrigated and rain-fed agriculture, which reduced crop productivity in semi-arid regions.Quantification of the impacts meteorological factors and soil moisture have on plant productivity is critical when assessing crop growth and sustainability in semi-arid regions. Field experiments conducted in 2021 and 2022 investigated the effects of drought duration on potato leaf photosynthetic characteristics. There were five treatments: drought stress with soil water at 55% (T ₁ ), 65% (T ₂ ), and 75% (T ₃ ) field water capacity; sufficient water (control) at 80% (T ₄ ), and waterlogging at 85% (T ₅ ). Soil moisture content ( W _r ) strongly affected potato photosynthesis. In 2022 (continuous drought for 23 days), drought stress had a greater effect on the potato leaf light response parameters than waterlogging. However, in 2021 (continuous drought for 29 days), both drought and waterlogging significantly affected the parameters. The critical points corresponding W _r for stomatal limitation corresponding were 67.5%, and 56.7% in 2022 and 2021, respectively. The increase in drought duration probably led to an increase in the potato water range required to meet the water demand for photosynthesis. The water threshold for potatoes in semi-arid areas was predicted using a model. The predictedsoil water threshold ranges in 2021 were 30.9–61.4% for low-yield and low-efficiency water, 61.4–68.6% for middle-yield and low-efficiency water, 70.1–96.3% for high-yield and high-efficiency water, which were greater than in 2022 because potato growth required more water due to the longer drought period. The results will improve soil water management under different drought durations.