Growth, Yield and Water Use of Wheat under Elevated Carbon Dioxide

Rising atmospheric carbon dioxide (CO₂) concentration will result in drier and warmer conditions across much of the mid-latitudes, including Australia and New Zealand. Research at the Australian Grains Free Air Carbon Dioxide facility has shown that although wheat yield increased due to improved carbon supply, wheat grain protein, baking quality and important micronutrients such as Zn and Fe all declined. This research identified that nutrient management strategies will need review under elevated CO₂ conditions.

Changes in the pattern of wheat growth and the temporal pattern of nutrient demand mean new combinations of nutrient source, rate, time, and place will be needed, along with more efficient cultivars. Most important will be the development of strategies to stop protein changes and to maximize the benefits of the extra carbon available. This may be done by changing to ammonium-based N sources, use of foliar N fertilizer during grain filling, and by building on current research that is developing more N efficient cultivars. For current C3 crops such as wheat, estimated atmospheric CO₂ concentrations in the year 2050 could increase N demand by 20%, and that higher N demand will require balanced nutrition with extra P, K, S, and micronutrients.