Drought stress effects on wheat are mitigated by atmospheric CO2 enrichment

Abstract

-The atmospheric CO 2 concentration is predicted to increase and to generate a rise in the global surface temperature, and change the seasonal precipitation pattern. This could aggravate the severity of summer drought conditions and affect crop yield. We studied the effect of the interaction of CO 2 and water supply on seasonal absorption of photosynthetically active radiation and radiation-use efficiency of aboveground biomass production to understand the processes contributing to final yield. Wheat was grown over two years in open-top chambers at present or future (+280 ppmv) atmospheric CO 2 concentration and under sufficient water supply or drought stress in lysimeters with a soil depth of 0.4 m (first year) or in the field with unrestricted root growth (second year). Drought stress was started after the first node stage by halving the water supply. Our results show that under sufficient watering, CO 2 enrichment did not affect the green area index or seasonal radiation absorption. Drought stress always decreased the green area index and accelerated canopy senescence, which in the second year resulted in a decrease of 23% in the seasonal radiation absorption under the present atmospheric CO 2 concentration. CO 2 enrichment stimulated the green area index under drought stress in the second year and seasonal radiation absorption was only decreased by 16%. Radiation-use efficiency was reduced by drought and increased by CO 2 elevation and the CO 2 effect was higher under restricted (+60%) than under sufficient watering (+32%). This implies that CO 2 enrichment enhanced final biomass and grain yield by less than 10% under well-watered conditions and by more than 44% under drought stress conditions, respectively. This study indicates that the increase in atmospheric CO 2 concentration will attenuate the effects of summer drought on wheat grain yield.CO 2 enrichment / drought / leaf area index / radiation absorption / radiation-use efficiency / water-use efficiency / wheat

Assessing Uncertainties of Water Footprints Using an Ensemble of Crop Growth Models on Winter Wheat

“…However, our results from the Braunschweig FACE experiment revealed, that the coefficient of variation for the simulated transpiration at elevated CO 2 was slightly smaller than for the ambient concentration. Although some models did not reflect the reduction of water use caused by rising CO 2 concentration as it was shown in a field chamber study with wheat by [44], the beneficial effect on crop yields was reflected by all models leading to a decrease of water footprint under elevated CO 2 . This was in agreement with the observed increase of water use efficiency [44].…”

“…Although some models did not reflect the reduction of water use caused by rising CO 2 concentration as it was shown in a field chamber study with wheat by [44], the beneficial effect on crop yields was reflected by all models leading to a decrease of water footprint under elevated CO 2 . This was in agreement with the observed increase of water use efficiency [44]. However, the fact that reduction of water use was not reflected in some model results did not mean that the effect of increasing CO 2 on stomata resistance was not considered at all in these models.…”

Projected Dryland Cropping System Shifts in the Pacific Northwest in Response to Climate Change

“…In the CF zone, TUE increased from 4.96 (baseline) to 6.17 and 6.97 g kg −1 under RCP 4.5 and 8.5, respectively, which combined with a slight increase in crop transpiration explain the relatively larger future yield responses in this AEC. Evidence from field CO 2 enrichment experiments have shown increased wheat yields, decreased transpiration, and increased TUE with elevated CO 2 ), more so for water stressed than for well-irrigated crops (Chaudhuri et al, 1990;Tubiello et al, 1999;Manderscheid and Weigel, 2007). The latter has also been reported for C4 crops such as maize (Manderscheid et al, 2014) and sorghum (Conley et al, 2001) despite small gains in biomass production, with data suggesting that future high CO 2 environments (increased temperature effects not accounted for) will increase dryland productivity (Conley et al, 2001).…”

Drought and Carbon Cycling of Grassland Ecosystems under Global Change: A Review

“…Atmospheric CO 2 enrichment can enhance NPP and mitigate the negative effects of droughts on GPP and NEE [31,79]. Likewise, elevated CO 2 concentrations alleviate the negative effects of droughts on soil respiration, principally due to the promotion of carbon assimilation, which increases the substrate supply for respiration in both roots and soil microorganisms [80].…”