SoyFACE: the Effects and Interactions of Elevated [CO2] and [O3] on Soybean

The SoyFACE experiment is the first to focus on the affects of e[CO2] and e[O3] on a seed legume under fully open-air conditions. The experiment mimicked e[CO2] and e[O3] predicted for the middle of this century and was conducted in one of the world’s major production areas for corn and soybean under cultivation and management techniques standard for the industry in the United States corn-belt region.Growth of soybean at e[CO2] resulted in an approximately 25 % increase in the daily integral of net leaf CO2 uptake, a 20% increase in the rate of light saturated CO2 uptake, a 15 % increase in seed yield, a 15 % increase in above ground primary productivity, and a 20 % increase in node number. Growth of soybean at e[CO2] also resulted in approximately a 30 % decrease in mid-day stomatal conductance, a 10 % decrease in stomatal conductance averaged over the day, an 8% decrease in the limitation of photosynthesis by stomatal conductance, and a 2–3 % decrease in harvest index.