Effects of Single and Multifactor Treatments with Elevated Temperature,CO2 and Ozone on Oilseed Rape and Barley

We investigated the effect of elevated CO₂], O₃] and temperature on plant productivity and if these climate factors interacted with each other in multifactor treatments. The climate effects were studied in 14 different cultivars/lines of European spring oilseed rape (Brassica napus L.) and spring barley (Hordeum vulgare L.). Seven genotypes of each species were cultivated in six single‐ and multifactor treatments with ambient or elevated CO₂ (385 ppm and 700 ppm), O₃ (20 ppb and 60 ppb) and temperature (12/19 °C and 17/24 °C). Growth and production parameters were measured. Elevated CO₂ increased yield and biomass. Seed number increased by about 47 % in barley and by 26 % in oilseed rape, but in oilseed rape, the TSW was significantly decreased, possibly because of shortening of the seed filling period. Higher temperatures decreased yield and biomass significantly in both species. A significantly decreased yield and thousand grain weight was also seen in barley due to elevated O₃. The multifactor combination of elevated CO₂, O₃ and temperature showed a decrease in growth and production in the two species, though not statistically significant for all parameters. This trend suggests that the expected increase in the plant production in northern Europe, indicated by Intergovernmental Panel on Climate Change (IPCC) as a consequence of increased CO₂] and temperature, may not hold, due to interactions between these abiotic factors.