Tuesday, November 14, 2006 - 2:35 PM

Farms of the Future: Soybean Productivity and Yield in a High-CO2, High-O3 World.

Kelly McConnaughay1, Elizabeth Brewer2, Anna Abts1, Pamela Beaver3, Sherri Morris3, Patrick Morgan4, and Stephen Long5. (1) Bradley Univ, 1501 W. Bradley Ave, Peoria, IL 61625, (2) Oregon State Univ, Crop & Soil Sciences, 3029 Agricultural & Life Sciences, Corvallis, OR 97331, (3) Bradley University, 1501 W. Bradley Avenue, Peoria, IL 61625, (4) USDA-ARS, Plant Science Research Unit, 3127 Ligon Street, Raleigh, NC 27695, (5) Univ of Illinois, 190 Edward R. Madigan Labs, 1201 W. Gregory Dr, Urbana, IL 61801-3838

Atmospheric CO2 is predicted to increase from current levels of 375 ppm to 550 ppm by 2050. Atmospheric ozone (O3) is also increasing. Increases in these atmospheric gases can have profound impacts on the growth and productivity of crop plants: CO2 through its direct impacts on photosynthesis and plant water use, and O3 through its direct negative impacts on photosynthesis. Here we report data on effects of increased levels of CO2 and O3 on growth and productivity in soybeans from a large-scale, multi-investigator FACE study. We monitored biweekly growth and seed yield for field-grown soybean exposed to current and predicted future atmospheric concentration of CO2 and/or O3 for two consecutive years (2004 and 2005). In both years, increased CO2 availability resulted in increased aboveground net productivity and seed yield. In 2004, a year in which background levels of O3 were particularly low, soybean growth and seed yield were not affected by ozone levels, with the exception that leaf senescence was accelerated for soybeans exposed to high O3 and low CO2. In contrast, in 2005, elevated O3 reduced soybean productivity and seed yield, but elevated CO2 ameliorated this response. In addition, soybeans grown at elevated O3 levels produced smaller seeds. Overall, these results suggest that soybean crops exposed to increasing O3 pollution in the lower atmosphere may experience reduced productivity and yield, but that elevated CO2 may reduce these negative impacts. Similarly, predicted increases in crop productivity and yield due to increased CO2 availability may be offset by decreases in productivity due to O3 pollution.