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

The likely consequences of future high revels of atmospheric CO2 concentration on wheat (Triticum aestivum L.) grain nutritional and baking quality were determined. Two free-air CO2 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 CO2 and FACE, respectively; loaf volume -22% and -29% at ambient CO2 and FACE, respectively). The data suggest that future elevated CO2 concentrations will exacerbate the deleterious effects of low soil nitrogen on grain quality, but with ample nitrogen fertilizer, the effects will be minor.