What was done
Soybeans were grown in open-top chambers receiving atmospheric CO2 concentrations of 371 and 708 ppm and ozone concentrations of 24 and 81 ppb to determine the interactive effects of these atmospheric trace gases on rubisco activity and various leaf properties.

What was learned
At ambient CO2 concentration, elevated ozone exposure reduced the amount and activity of rubisco per unit leaf area.  In addition, elevated ozone decreased leaf starch content by approximately 32%.  However, at elevated CO2 and ambient ozone concentrations, only the activity of rubisco, and not its amount, was reduced.  In addition, this treatment combination actually increased leaf starch content by as much as 148%, relative to that measured in leaves grown under ambient CO2 and ozone conditions.  Moreover, when exposed simultaneously to elevated CO2 and ozone, leaf rubisco content and activity, as well as leaf starch content, were similar to what they were in plants grown at elevated CO2 and ambient ozone concentrations, thus demonstrating a total amelioration of ozone-induced damage by atmospheric CO2 enrichment.

What it means
As the amount of CO2 in the atmosphere continues to rise, soybean plants will likely exhibit enhanced rates of photosynthesis, which will lead to greater synthesis of starch and other carbohydrates for supporting increased growth and development.  In addition, if the atmospheric ozone level continues to rise, the rising CO2 content of the air will likely protect soybeans and other crops from the adverse effects of ozone that reduce productivity, growth, and yield.