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

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 (eCO(2)) environment. A coupled device with climate chamber and weighing lysimeters was developed to explore the water-related yield responses of maize to eCO(2). Two experiments were conducted via this device under eCO(2) (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 eCO(2) 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) were found throughout the growing season. Dry matter per corncob at the final harvest decreased slightly under eCO(2) (mean of 7.7 g, 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 eCO(2) 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 < 0.05), the grain yield and water productivity were not improved noticeably by eCO(2). This study could provide significant insight into predicting future crop yield and hydrological changes under climate change. (c) 2020 Elsevier B.V. All rights reserved.