The optimal atmospheric CO₂ concentration for the growth of winter wheat (Triticum aestivum)

This study examined the optimal atmospheric CO₂ concentration of the CO₂ fertilization effect on the growth of winter wheat with growth chambers where the CO₂ concentration was controlled at 400, 600, 800, 1000, and 1200ppm respectively. I found that initial increase in atmospheric CO₂ concentration dramatically enhanced winter wheat growth through the CO₂ fertilization effect. However, this CO₂ fertilization effect was substantially compromised with further increase in CO₂ concentration, demonstrating an optimal CO₂ concentration of 889.6, 909.4, and 894.2ppm for aboveground, belowground, and total biomass, respectively, and 967.8ppm for leaf photosynthesis. Also, high CO₂ concentrations exceeding the optima not only reduced leaf stomatal density, length and conductance, but also changed the spatial distribution pattern of stomata on leaves. In addition, high CO₂ concentration also decreased the maximum carboxylation rate (Vc_max) and the maximum electron transport rate (J_max) of leaf photosynthesis. However, the high CO₂ concentration had little effect on leaf length and plant height. The optimal CO₂ fertilization effect found in this study can be used as an indicator in selecting and breeding new wheat strains in adapting to future high atmospheric CO₂ concentrations and climate change.