What was done
For three consecutive years, spring wheat was sown directly in the field and grown within open-top chambers receiving ambient or elevated (700 ppm) CO2 concentrations.  In addition, half of the chambers had greenhouses built around them to facilitate warming the air within them to 3°C above ambient field temperature.  With this setup, the authors investigated the interactive effects of elevated CO2 and temperature on the growth and yield of a spring wheat variety commonly grown in Finland.

What was learned
Although the high temperature treatment shortened the time from anthesis to maturity in all three years, elevated CO2 had no effect on the rate of plant development.  Total biomass, however, increased by 17% and 23% with atmospheric CO2 enrichment at normal and elevated temperatures, respectively.  Likewise, elevated CO2 increased grain yields by 12% and 20% at ambient and high temperatures, respectively.

What it means
These data suggest that as the CO2 content of the air continues to rise, both biomass and grain yield will increase in this Finnish spring wheat cultivar.  Furthermore, if air temperatures in this region increase, the growth stimulation brought about by rising atmospheric CO2 levels will rise even more.  Consequently, if any CO2-induced global warming occurs, it will likely produce a climate in Finland that is more conducive to agriculture than that of the present, which could facilitate the planting of even more productive wheat varieties with greater sink potential to presumably produce substantially larger yields.