Significant decrease in yield under future climate conditions: Stability and production of 138 spring barley accessions

Abstract The response in production parameters to projected future levels of temperature, atmospheric carbon dioxide ([CO 2 ]), and ozone ([O 3 ]) was investigated in 138 spring barley accessions. The comprehensive set of landraces, cultivars, and breeder-lines, were during their entire life cycle exposed to a two-factor treatment of combined elevated temperature (+5 °C day/night) and [CO 2 ] (700 ppm), as well as single-factor treatments of elevated temperature (+5 °C day/night), [CO 2 ] (700 ppm), and [O 3 ] (100–150 ppb). The control treatment was equivalent to present average South Scandinavian climate (temperature: 19/12 °C (day/night), [CO 2 ]: 385 ppm). Overall grain yield was found to decrease 29% in the two-factor treatment with concurrent elevation of [CO 2 ] and temperature, and this response could not be predicted from the results of treatments with elevated [CO 2 ] and temperature as single factors, where grain yield increased 16% and decreased 56%, respectively. Elevated [O 3 ] was found to decrease grain yield by 15%. Substantial variation in response to the applied climate treatments was found between the accessions. The results revealed landraces, cultivars, and breeder-lines with phenotypes applicable for breeding towards stable and high yield under future climate conditions. Further, we suggest identifying resources for breeding under multifactor climate conditions, as single-factor treatments did not accurately forecast the response, when factors were combined.