Combined Effects of Water Shortage and CO ₂ Enrichment on Yield and Water Use Properties of Barley ( <

ABSTRACT

A selection of winter barley genotypes was investigated for their responses to water shortage under different CO ₂ concentrations in a greenhouse. The experiment was conducted in a 2*2 factorial design. Plants were grown either with optimum water supply or simulated drought in the BBCH 59 stage at current (~400 ppm CO ₂ ) or elevated CO ₂ concentrations (~700 ppm CO ₂ ) with identical climatic conditions. Yield parameters (aboveground biomass and grain yield), water use and water use efficiency (WUE; kg m ⁻³ ) were calculated. Drought stress induced a decrease in yield production, and the rate of yield reduction was higher at 700 ppm CO ₂ concentration. On average for the genotypes studied, water withdrawal resulted in a 20.01% and 22.0% reduction in grain yield at 400 ppm and 700 ppm CO ₂ levels, respectively. Under optimum irrigation, BCC570, BCC607, Ketos, BCC887, HOR12808 and Kaskade showed significant positive CO ₂ responses. Under a limited water supply, positive CO ₂ reactions were only observed for BCC570, Ketos and BCC1585 genotypes; however, a significant positive CO ₂ reaction regarding the yield production was observed for Panda. The carbon dioxide enrichment significantly increased water use efficiency under optimum watering conditions by 24.57% and drought‐stressed conditions by 21.72%. However, the water shortage significantly increased water use efficiency under both 400 ppm (10.48%) and 700 ppm (12.36%) CO ₂ .