Submitted to: Keystone Symposia
Publication Type: Abstract Only
Publication Acceptance Date: January 17, 2013
Publication Date: N/A
Technical Abstract: While the future crop growing environment is likely to be warmer and with more variable water available, the stimulation of C3 photosynthesis by elevated CO2 concentration provides a potential benefit of global climate change. However, experimental field studies suggest that C3 crops fall short of the theoretical maximum stimulation in yield when grown at elevated CO2. This may be because crops are not adapted to current atmospheric CO2 concentrations, much less future elevated CO2 concentrations, and lack the sink capacity to maximize the potential gain in carbon from greater photosynthetic rates. However, only a tiny fraction of available germplasm has been screened for CO2 response. At the SoyFACE experiment in central Illinois, over 20 genotypes of soybean (Glycine max Merr.) have been screened for CO2 responsiveness. On average, seed yield is stimulated by ~15%; however, genotypes with a range of responses from no stimulation in yield to 25% stimulation in yield have been identified. We investigated the photosynthetic basis for variation in CO2 response in two soybean lines in an effort to determine mechanisms for maximizing yield responses to elevated CO2. Changes in photosynthetic acclimation as well as changes in partitioning of carbon to seed biomass underpin variation in soybean yield responses to elevated CO2. These results will be discussed in combination with efforts to transgenically modify soybean to maximizing its production in a high CO2 world.