Plant plasticity in the face of climate change - CO2 offsetting effects to warming and water deficit in wheat. A review.

Future crop production will depend on plant plasticity in response to increases in atmospheric CO2, mean temperature, heatwave and drought events. The present review intends to highlight the impact of interactions between high CO2 levels, warming and water deficit in existing published experimental data in the case of wheat. To do so, we identified experiments quantifying the effects of such interactions on traits related to crop productivity and water use. We used the collected data to estimate plasticity indices assessing compensation and interaction between elevated CO2 and adverse climatic conditions, bringing a new perspective on the matter. In the studied data, even though there is an important variability, we found that crop productivity tends to decrease despite the positive effects of the rise in CO2 concentration. Conversely, with elevated CO2, water consumption tends to decrease despite the warmer conditions. We hypothesized that the positive effect of CO2 on crop productivity is greater under drought conditions, which is confirmed in 54% of the experiments. This review highlights the need to acquire further experimental data under possible future conditions to calibrate and validate crop models: their range of validity requires more thorough testing under the wide range of projected environmental conditions.