Physiological responses of cotton roots and soil microbial adaptation to drought hardening

Background: As global climate changing significantly exacerbated the frequency and intensity of drought stress, posing severe challenges to the sustainable development of agriculture in arid regions. Aims: This investigation employed integrated physiological and metagenomic analyses to unravel the physiological responses of cotton roots and the changes of soil microbial communities induced by drought hardening. Then, by integrating the physiological responses of the aboveground parts and yield performance, a comprehensive analysis was conducted to provide optimized irrigation strategies for cotton fields in moisture-limited regions. Methods: The experiment was conducted in 2024 at Huaxing Farm in Changji, Xinjiang, using the Zhongmian 113 variety, with three drought hardening treatments during the seedling stage. These treatments were saving 20% (D1), 30% (D2), and 40% (D3) of irrigation amount respectively, comparing to the control (CK, conventional full irrigation). Results: The results showed that the D1 treatment was identified as moderate drought hardening, which based on cotton growth and yield; The D1 treatment significantly enhanced the antioxidant capacity and membrane integrity maintenance in cotton roots; Additionally, the D1 treatment altered soil microbial diversity, partially optimizing the microbial community structure and forming a dominant bacterial group— Gemmatimonadales . Conclusions: This integrated microbial-plant analysis hypothesized that Gemmatimonadales might interact synergistically with cotton roots during the budding stage to enhance the drought resistance of cotton. The research provided a foundation for revealing the enhancing drought- resistance- mechanisms of root-microbe interactions in cotton via drought hardening in arid regions.