Seasonal responses of maize growth and water use to elevated CO2 based on a coupled device with climate chamber and weighing lysimeters

Abstract The increase in atmosphere carbon dioxide (CO2) concentrations has been the most important environmental change experienced by agricultural systems. It is still uncertain whether grain yield of the global food crop of maize will remain unchanged under a future elevated CO2 (eCO2) environment. A coupled device with climate chamber and weighing lysimeters was developed to explore the water-related yield responses of maize to eCO2. Two experiments were conducted via this device under eCO2 (700 ppm) and current CO2 (400 ppm) concentrations. Seasonal changes in multiple growth indicators and related hydrological processes were compared between these two experiments. The results showed that the eCO2 effects were not significant on several indicators, i.e., the leaf carbon (C) content, nitrogen (N) content, chlorophyll content, C/N ratio, net photosynthesis rate, and leaf area index over the entire growing season (p > 0.05). Nevertheless, the transpiration rate (Tr) significantly reduced during the seedling to filling stages but notably increased at the maturity stage due to eCO2 (p   0.05). Soil water storage was not significantly conserved by the decline of Tr except during the filling stage. Soil evaporation was likely promoted by eCO2 that the total evapotranspiration changed little (1.2%) over the entire growing season. Although the leaf water use efficiency increased significantly at every growth stage (mean of 27.3%, p