Research has shown that elevated CO2 can increase wheat yields at the expense of grain quality traits such as nitrogen and protein content. Yet scientists do not fully understand the range of grain quality changes that can occur at different stages of wheat development or the biochemical mechanisms behind them. A collaborative study from the University of the Basque Country, Universidad de Talca, Université Paris-Sud, and Université Paris-Sud examined the impact of rising CO2 levels on the yield, quality, and metabolism of wheat plants during grain formation and at maturity.
In the study, the team grew wheat in greenhouses at normal (400 ppm) or elevated (700 ppm) CO2 concentrations. They found that wheat grown under elevated CO2 levels showed a 104% higher yield of mature grain. However, the nitrogen content of the grain was 0.5% lower under these conditions, and there were small declines in protein content and free amino acids. The researchers used GC/MS to analyze metabolic changes in the grains at different developmental stages.
Among other changes, elevated CO2 altered the levels of certain nitrogen-containing amino acids during grain formation and at maturity. Although the metabolic changes they detected had modest impacts on final grain quality, the effects could be amplified by other changes in a plant’s environment, such as limited nitrogen availability or drought conditions.