Title: Genetic and environmental limitations on crop responses to elevated [CO2] Authors
|Bishop, K -|
|Leakey, Andrew D B -|
Submitted to: International Congress of Photosynthesis
Publication Type: Abstract Only
Publication Acceptance Date: May 29, 2013
Publication Date: N/A
Technical Abstract: While the future crop growing environment is likely to be warmer and with more variable water availability, 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. It also may be because other environmental factors including temperature or water availability limit the maximum response of crops to elevated [CO2]. In this talk I will synthesize data from published field experiments exposing crops to elevated [CO2] in order to test two general hypotheses: (1) the relative stimulation of crop yield by elevated [CO2] is greater at higher temperatures; (2) the relative stimulation of crop yield by elevated [CO2] is greater in water-limited conditions. Then I will discuss results from the Soybean Free Air CO2 Enrichment (SoyFACE) experiment, where over 20 genotypes of soybean (Glycine max Merr.) have been screened for CO2 responsiveness over the past decade. On average, seed yield was 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.