Submitted to: Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/15/2014
Publication Date: 6/13/2014
Citation: Rosenthal, D.M., Ruiz-Vera, U.M., Siebers, M.H., Gray, S.B., Bernacchi, C.J., Ort, D.R. 2014. Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of Soybean (Glycine max) at elevated [CO2] and temperatures under fully open air field conditions. Plant Science. 226:136-146. Interpretive Summary: Improving crop productivity within the context of climate change remains a critical goal if we are to meet global food demands. While photosynthetic responses to climate change differ among species and genotypes the greater than expected acclimation of key photosynthetic processes reported here has important implications for C3 photosynthesis beyond that of soybeans. Indeed, assessing the magnitude and direction of acclimation is crucial to our understanding of global carbon flux and food security because A modulates the largest exchange of carbon from the atmosphere into ecosystems and is an important determinant of crop yields. Finally, and perhaps most importantly, photosynthetic acclimation to temperature and CO2 when combined under field conditions may be greater than reported in some enclosure studies, underscoring the importance of continuing field assessments of climate change impacts on plants.
Technical Abstract: The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on 1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the maximum carboxylation capacity of Rubisco (Vc,max) and the maximum potential linear electron flux through photosystem II (Jmax), 2) the associated responses of leaf structural and chemical properties related to A, as well as 3) the physical limitations imposed on A, for soybean over two growing seasons in a conventionally managed agricultural field in Illinois, USA. Acclimation to elevated [CO2] was consistent over two growing seasons with respect to Vc,max and Jmax. However, elevated temperature significantly decreased Jmax contributing to lower photosynthetic stimulation by elevated CO2. Large seasonal differences in precipitation altered soil moisture availability modulating the complex effects of elevated temperature and CO2 on biochemical and structural properties related A. Elevated temperature also reduced the benefit of elevated [CO2] by eliminating decreases in stomatal limitation at elevated [CO2]. These results highlight the critical importance of considering multiple environmental factors (i.e. temperature, moisture, [CO2¬]) when trying to predict plant productivity in the context of climate change.