Growth and yield responses of spring wheat to increasing carbon dioxide, ozone and physiological stresses: a statistical analysis of 'ESPACE-wheat' results.

摘要

In open-top chamber experiments at 8 sites throughout Europe, wheat cv. Minaret was exposed to increased CO2 and/or O3, water stress and different N nutrition regimes for up to 3 years. In general, plants did not respond significantly to O3, suggesting that this cultivar is relatively tolerant to the O3 levels applied. The main effect of CO2 was a significant increase in grain yield and aboveground biomass in almost all experiments. Significant interactions between CO2 and other factors were not common, although modifications in N and water supply regimes also had significant effects on grain yield and biomass. In addition, climatic factors (in particular mean air temperature and global radiation) were identified as important co-variables affecting grain yield or biomass. On average, the yield increase as a result of a doubling of [CO2] was 35% compared with that observed at ambient [CO2]. However, linear regressions of grain yield or aboveground biomass for individual experiments revealed a large variation in the quantitative responses to CO2 enrichment (yield increase ranging from 11 to 121%). Multiple regression analyses performed to evaluate the relative importance of the measured environmental parameters on grain yield indicated that although yield was significantly related to 5 independent variables (24 h mean CO2 concentration, 12 h mean O3 concentration, temperature, radiation and water stress), a large proportion of the observed variability remained unexplained.