Elevated CO2, drought and soil nitrogen effects on wheat grain quality

• The likely consequences of future high levels of atmospheric CO 2 concentration on wheat ( Triticum aestivum L.) grain nutritional and baking quality were determined. • Two free-air CO 2 enrichment (FACE; 550 mmol mol − 1 ) experiments were conducted at ample (Wet) and limiting (Dry) levels of irrigation, and a further two experiments at ample (High-N) and limiting (Low-N) nitrogen concentrations. Harvested grain samples were subjected to a battery of nutritional and bread-making quality tests. • The Dry treatment improved grain quality slightly (protein +2%; bread loaf volume +3%). By contrast, Low-N decreased quality drastically (protein − 36%; loaf volume − 26%). At ample water and N, FACE decreased quality slightly (protein − 5%; loaf volume − 2%) in the irrigation experiments and there was no change in the nitrogen experiments. At Low-N, FACE tended to make the deleterious effects of Low-N worse (protein − 33% and − 39%, at ambient CO 2 and FACE, respectively; loaf volume − 22% and − 29% at ambient CO 2 and FACE, respectively). • The data suggest that future elevated CO 2 concentrations will exacerbate the deleterious effects of low soil nitrogen on grain quality, but with ample nitrogen fertilizer, the effects will be minor.