Effects of irrigation management on soil water-heat-salinity dynamics and water productivity of winter jujube in saline-alkaline soils under a plastic-shed system

Plastic sheds have been widely applied to agricultural production. However, the soil sustainability in plastic sheds has been seriously threatened by drought and soil salinization in Southern Xinjiang, China. The objective of this study was to explore the soil water-heat-salinity dynamics and water productivity of winter jujube in plastic shed system at saline-alkaline soils under drip irrigation. A two–year experiment (2023–2024) was conducted on winter jujube under various drip irrigation amounts (W1: 60 %ETc, W2: 80 %ETc, W3: 100 %ETc and W4: 120 %ETc, ETc, crop evapotranspiration) to investigate the soil moisture, soil electrical conductivity, soil temperature, winter jujube growth parameters (i.e., new shoot length and panicle length), winter jujube yield and water productivity. The results indicated that increasing irrigation amount increased soil moisture in the 0–100 cm soil layer and decreased the average soil conductivity during the entire growth period. Furthermore, the increase of irrigation amount reduced the soil temperature to prevent heat stress for winter jujube during the whole growing season. High irrigation amount was beneficial for new shoot length and panicle length, but it was not conducive to improving winter jujube yield and water productivity. Conversely, although the low irrigation amount (W1) was not conducive to decreasing soil conductivity and soil temperature, it resulted in high water productivity. In addition, the Pearson correlation analysis indicated that the soil temperature and soil electrical conductivity were negatively correlated with the winter jujube growth parameters and yield. Based on a comprehensive evaluation using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) model, the W2 treatment was identified as the optimal irrigation strategy for improving winter jujube production in saline-alkaline soils under plastic sheds. Overall, the optimal irrigation management reduced soil temperature and salinity, and increased soil water in the root zone by regulating soil water-heat-salinity dynamics, which collectively promoted winter jujube growth. This research provides a scientific basis for managing drip-irrigated winter jujube in saline-alkaline soils under plastic sheds in arid agroecosystems, by clarifying the responses of growth and production to soil hydrothermal and salinity conditions.