Responses of the Leaf Water Physiology and Yield of Grapevine via Different Irrigation Strategies in Extremely Arid Areas

The contradiction between water supply and demand has become increasingly prominent due to the large agricultural water consumption and low irrigation water use efficiency (IWUE) in the extremely arid area of Xinjiang, which needs to be solved by efficient irrigation. In this study, the effects of different irrigation levels (the lower and upper limits of irrigation (LULI) were 50-80%, 60-90%, and 70-100% of the field capacity (FC), respectively) under two irrigation methods (root zone irrigation (RZI) and furrow irrigation (FI)) on the photosynthetic physiology and yield of grape were analyzed to explore suitable irrigation schemes in extremely arid areas. The results show that the diurnal variation curve of the net photosynthetic rate (Pn) of grape leaves in the extreme arid region was not sensitive to the response of irrigation methods. However, RZI could improve the apparent quantum efficiency and maximum photosynthetic rate by 60.00% and 31.25%, respectively, reduce the light compensation point by 17.91%, and alleviate the photosynthetic lunch break phenomenon. Under FI, the physiological indexes of leaves increased with the increase in the LULI, while the Pn and SPAD values were the largest under RZI when the LULI was 60-90% of FC. The daily average Pn value of T2 in 2021 and 2022 ranged from 12.93 to 17.77 mu mol center dot m(-2)center dot s(-1). Compared with FI, RZI significantly improved the leaf water potential, Pn, and SPAD values by increasing the soil water content (SWC) of the 40-80 cm soil layer by 5.04-8.80%, which increased the yield by 6.86-18.67%. The results show that the yield and water use efficiency reached the peak when the LULI was 60-90% of FC under RZI, which could provide theoretical support for efficient irrigation of vineyards in extremely arid areas.