土壤水分水平对干旱区冬小麦糖积累及产量的调节 postprint

Abstract: Winter wheat is a major cereal crop in northwestern China. However, increases in its productivity are still constrained by water scarcity and inappropriate irrigation practices. A two-year field experiment was conducted from 2022 to 2024 using three soil moisture lower limits, namely 50%, 65%, and 80% of field capacity (FC), at different growth stages of winter wheat. Six treatments (W1-W6) were designed to investigate the regulatory effects of soil moisture lower limits on water consumption, plant growth, grain enzyme activity, sugar accumulation, yield, and water use efficiency (WUE), followed by a comprehensive benefit evaluation. The results showed that, at maturity, the W3 treatment was conducive to wheat growth and yield formation in both experimental years. Compared with the W6 treatment, W3 increased growth parameters by 14.05%-17.42%, accelerated the grain filling rate by 1.22-1.35 times, increased yield by 20.22%, and improved WUE by 19.15%. Under the W3 treatment, the activities of three key enzymes involved in grain sugar synthesis were less impaired, and grains retained a certain carbon assimilation capacity during the middle and late grain-filling stages. Sugar accumulation under W3 increased by 13.38%-19.86% compared with W6, indicating that W3 was favorable for sucrose and starch synthesis in grains. Correlation analysis and partial least squares path modeling (PLS-PM) further demonstrated that appropriate regulation of soil moisture could improve plant growth, enhance grain enzyme activity, and promote sucrose metabolism and starch accumulation, thereby increasing yield and WUE. In the comprehensive benefit evaluation, W3 ranked first in both years, with yields of 10625.54 and 10344.43 kg·hm-2, respectively. In conclusion, using 80% FC as the soil moisture lower limit from heading to grain filling, and 65% FC during the other growth stages, with FC as the upper irrigation limit, represents an optimal irrigation strategy for winter wheat cultivation in arid regions. This study clarifies a relatively irrigation regime and provides a basis for evaluating and selecting improved management practices for winter wheat production.