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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #338846
Title: Leaf and canopy scale drivers of genotypic variation in soybean response to elevated carbon dioxide concentration

Author
item SANZ-SAEZ, ALVARO - University Of Illinois
item KOESTER, ROBERT - University Of Illinois
item ROSENTHAL, DAVID - Ohio University
item MONTES, CHRISTOPHER - University Of Illinois
item Ort, Donald
item Ainsworth, Elizabeth - Lisa

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2017
Publication Date: 4/1/2017
Citation: Sanz-Saez, A., Koester, R., Rosenthal, D., Montes, C., Ort, D.R., Ainsworth, E.A. 2017. Leaf and canopy scale drivers of genotypic variation in soybean response to elevated carbon dioxide concentration. Global Change Biology. 23(9):3908-3920.

Interpretive Summary: Crops are growing at a higher atmospheric concentration of carbon dioxide today than they have experienced at any point in the history of crop domestication. While many crop varieties show variation in response to growth at elevated carbon dioxide concentration, little is known about the physiological mechanisms contributing to this variation. This study investigated the response of two soybean varieties previously shown to have different seed yield responses to elevated carbon dioxide concentrations. Photosynthesis, crop canopy properties and yield was measured over 3 growing seasons. The results show that the responsive genotype had improved canopy light interception at elevated carbon dioxide, and greater photosynthesis and harvest index at both ambient and elevated carbon dioxide. The results provide the basis for modeling variation in crop responses to elevated carbon dioxide concentrations and emphasize the importance for cultivar selection in maximizing yields under future carbon dioxide concentrations.

Technical Abstract: The atmospheric [CO2] in which crops grow today is greater than at any point in their domestication history, and represents an opportunity for positive effects on seed yield that can counteract the negative effects of greater heat and drought this century. In order to maximize yields under future atmospheric [CO2], we need to identify and study crop cultivars that respond most favorably to elevated [CO2] and understand the mechanisms contributing to their responsiveness. Soybean (Glycine max Merr.) is a widely grown oilseed crop and shows genetic variation in response to elevated [CO2]. However, few studies have studied the physiological basis for this variation. Here we examined canopy light interception, photosynthesis, respiration and radiation use efficiency along with yield and yield parameters in two cultivars of soybean (Loda and HS93-4118) previously reported to have similar seed yield at ambient [CO2], but contrasting responses to elevated [CO2]. Seed yield increased by 26% at elevated [CO2] in the responsive cultivar Loda, but only by 11% in HS93-4118. Canopy light interception and leaf area index were greater in HS93-4118 in ambient [CO2], but increased more in response to elevated [CO2] in Loda. Radiation use efficiency and harvest index were also greater in Loda than HS93-4118 at both ambient and elevated [CO2]. Daily C assimilation was greater at elevated [CO2] in both cultivars, while stomatal conductance was lower. Photosynthetic capacity, specifically electron transport capacity was also greater in Loda than HS93-4118, but there was no difference in the response of photosynthetic traits to elevated [CO2] in the two cultivars. Overall, this greater understanding of leaf- and canopy-level photosynthetic traits provides a strong conceptual basis for modelling genotypic variation in response to elevated [CO2].