1.西北农林科技大学;2.Northwest A &3.F University
National Key Research and Development Program（2021YFD1900700）；Key Research and Development Project of Shaanxi Province（2023-ZDLNY-53）；
微咸水灌溉是缓解农业用水紧张、保障粮食生产的重要途径之一，但灌溉水中的可溶性盐会导致土壤盐分累积，进而影响作物生长，寻求适宜的灌溉水盐分浓度是咸水、微咸水资源得到安全利用的有利保障。研究采用遮雨盆栽试验种植冬小麦，以去离子水为对照（CK），添加氯化盐形成不同浓度的微咸水处理，灌溉水电导率（ECw）分别为：0.26（CK）、3.00（S1）、5.26（S2）、7.07（S3）、9.24（S4） dS/m，研究土壤水盐分布和冬小麦生长、光合生理及产量形成的响应。结果表明：不同浓度微咸水灌溉下土壤含水率、土壤含盐量随盐分浓度的增加而增大。冬小麦收获后CK及S1-S4处理下0~40 cm土层土壤饱和浸提液电导率（ECe）分别为0.66、4.89、7.88、9.34、10.16 dS/m；与CK相比，灌溉水电导率为3.00、5.26 dS/m时，冬小麦生长、光合生理指标、产量无显著差异，而为7.07、9.24 dS/m时显著降低，当灌溉水电导率为9.24 dS/m时，冬小麦净光合速率、最大株高、最大叶面积、成熟期地上部干物质量、根系干物质量以及产量相比CK分别降低了71.00%、2.81%、15.33%、15.55%、47.25%、27.53%。利用FAO分段函数拟合计算得冬小麦灌溉微咸水电导率阈值为5.82 dS/m。综合考虑冬小麦生长、光合生理指标及土壤理化性质，建议使用微咸水灌溉冬小麦时，ECw不宜超过5.82 dS/m，否则每增加1 dS/m，冬小麦相对产量下降8.8%。该研究可为微咸水安全利用提供理论支撑。
Saline water irrigation is one of the important ways to alleviate the shortage of agricultural water and ensure food production. However, soluble salt in irrigation water leads to soil salt accumulation, which affect the growth of crops. Seeking suitable salt concentration in irrigation water is a favorable guarantee for the safe utilization of saline water resources. In this study, a rain shielding pot experiment was conducted to plant winter wheat. The deionized water was used as control (CK), and chloride salts were added to form saline water with different salt concentration. The electrical conductivity of irrigation water (ECw) was 0.26 (CK), 3.00 (S1), 5.26 (S2), 7.07 (S3), 9.24 (S4) dS/m respectively. The soil water and salt distribution, growth, photosynthetic physiology and yield formation of winter wheat were studied. The results showed that soil water content and electrical conductivity increased with the increase of saline water salt concentration under saline water irrigation. The electrical conductivity of soil extract (ECe) in 0-40 cm soil layer was 0.66, 4.89, 7.88, 9.34, 10.16 dS/m under CK and S1-S4 treatments after winter wheat harvest, respectively. Compared with CK, there was no significant difference in the growth, photosynthetic physiological indexes and yield of winter wheat when the conductivity of irrigation water was 3.00 and 5.26 dS/m, but it was significantly reduced when the conductivity of irrigation water was 7.07 and 9.24 dS/m. The net photosynthetic rate, maximum plant height, maximum leaf area, shoot dry matter mass at maturity stage, root dry matter mass and yield of winter wheat under 9.24 dS/m were decreased by 71.00%, 2.81%, 15.33%, 15.55%, 47.25% and 27.53% compared with CK, respectively. The threshold of saline water conductivity for irrigation of winter wheat was calculated as 5.82 dS/m using the fitting sum of FAO piecewise function. Considering the growth, photosynthetic physiological indexes of winter wheat and soil physical and chemical properties, it is suggested that ECw should not exceed 5.82 dS/m when saline water is used to irrigate winter wheat, otherwise, the relative yield of winter wheat will decrease by 8.8% with every increase of 1 dS/m. This study can provide theoretical support for the safe utilization of saline water.