Regulation of physiological and molecular response mechanisms of winter wheat to elevated atmospheric CO2 concentration under soil water deficit conditions

Global climate change has led to a continuous increase in atmospheric CO2 concentration, profoundly impacting agroecosystems and crop productivity. Understanding how crops adapt under adverse conditions, such as water deficit, remains a critical scientific challenge. Winter wheat, an important grain crop in arid regions, has not yet had its physiological and molecular response mechanisms to elevated CO2 fully elucidated. This study simulated varying CO2 concentrations and water supply levels under controlled conditions to systematically explore the regulatory effects of elevated CO2 on winter wheat under water stress by analyzing stomatal characteristics, photosynthesis, Rubisco enzyme activity, and the expression of related genes. The results showed that water deficit significantly inhibited photosynthetic rate and total biomass accumulation in winter wheat, but elevated CO2 effectively alleviated these negative effects. Specifically, elevated CO2 improved gas exchange efficiency, enhanced water use efficiency, and increased Rubisco enzyme activity and related gene expression. Additionally, by regulating stomatal behavior and the activity of key photosynthetic enzymes, elevated CO2 improved the growth performance of winter wheat under water stress. This study reveals the regulatory effects of elevated atmospheric CO2 on the physiological and molecular mechanisms of winter wheat under water deficit, providing theoretical insights into crop adaptation mechanisms in the context of climate change and scientific guidance for improving water use efficiency and optimizing wheat cultivation practices.