Elevated carbon dioxide changes grain protein concentration and composition and compromises baking quality. A FACE study

• Grain protein percent, composition and loaf volume were affected by eCO2.
• Amylograph peak viscosity and starch damage were significantly reduced under eCO2.
• Seasonal conditions and eCO2 affected wheat quality traits and dough rheology.
• Starch composition; A-type granules and amylose were not altered under eCO2.

Wheat is one of the major crops grown commercially and an important source of nutrition for humans. Changes in grain quality due to increasing levels of atmospheric CO2 could have far-reaching impacts to human diets globally. Future wheat-growing conditions are expected to be impacted by climate change, particularly increases in carbon dioxide. Elevated CO2 (eCO2) has been shown to increase plant growth and yield, yet changes in grain properties also affect product quality.Using Australian Grains Free Air CO2 Enrichment (AGFACE) technology we investigated the impacts of eCO2 on grain quality over three seasons.Elevated CO2 consistently decreased baking quality and grain protein percentage was consistently lower under eCO2, and protein composition changed towards a greater glutenin/gliadin ratio. Starch damage and amylograph peak viscosity were consistently reduced in the eCO2 treatment in all years and for all cultivars. For other traits such as grain weight, milling quality, dough rheology, A-type starch granules and pasting viscosity the same altered effects were not consistent for cultivar or over years. The results suggest that grain and product quality of wheat grown under eCO2 will be compromised in a high CO2 atmosphere, and this may offset some of the potential yield benefits of eCO2.