Rising atmospheric CO2 concentration affects mineral nutrient and protein concentration of wheat grain

Wheat (Triticum aestivum L. cv. Yitpi) was grown in the Australian Grains Free-Air Carbon dioxide Enrichment (AGFACE) facility under current ambient [CO2] (384 μmol mol -1) and elevated [CO2] (550 μmol mol -1) in combination with two different times of sowing (TOS) to investigate the interactive effect of [CO2] and grain filling conditions on wheat grain quality. Grains were sampled at harvest maturity and their protein and mineral nutrient (Ca, S, Zn and Fe) concentrations were measured. Protein concentration of the grain was decreased by 12.7% at elevated [CO2] and the largest reduction in grain protein was observed at the later TOS (TOS 2). Concentration of grain S, Ca, Fe and Zn were also significantly decreased at elevated [CO2]. Most of the grain mineral nutrient concentrations were significantly increased at the TOS 2 suggesting that rising temperature together with increased water stress are likely to offset some of the negative effects of elevated [CO2] on grain mineral concentrations