Does Elevated CO2 Protect Grain Yield of Wheat from the Effects of Ozone Stress?

Abstract

This study has investigated the effects of elevated CO2 and elevated O3, both singly and in combination, on the yield of spring wheat (Triticum aestivum L., cv. Minaret). Plants were grown in open-top chambers and exposed to three CO2 concentrations (ambient, 510 and 680 ppmv) and two O3 concentrations (ambient and ambient +50 or +90 ppbv) either from anthesis onwards or for the full growing season. To date, experiments that have investigated the interactive effects of these gases have shown a variety of responses, ranging from an amelioration of the damaging effects of high O3 to a greater sensitivity to O3 at elevated CO2. The effects on grain yield and yield com ponents were determined. Our results confirm that elevated CO2 provides some protection to a wheat crop against the damaging effects of O3 on grain yield. However, the level of protection varies from one growing season to the next and also appears to be related particularly to the timing of exposure to elevated O3