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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #331124
Title: Intensifying drought eliminates the expected benefits of elevated [CO2] for soybean

Author
item GRAY, S - University Of Illinois
item DEMODY, O - University Of Illinois
item KLEIN, S - University Of Illinois
item LOCKE, A - University Of Illinois
item MCGRATH, J - University Of Illinois
item PAUL, R - University Of Illinois
item ROSENTHAL, D - University Of Illinois
item RUIZ-VERA, U - University Of Illinois
item SEIBERS, M - University Of Illinois
item STRELLNER, R - University Of Illinois
item Ainsworth, Elizabeth - Lisa
item Bernacchi, Carl
item Ort, Donald

Submitted to: Nature Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2016
Publication Date: 9/5/2016
Citation: Gray, S.B., Demody, O., Klein, S.P., Locke, A.M., McGrath, J.M., Paul, R.E., Rosenthal, D.M., Ruiz-Vera, U.M., Seibers, M.H., Strellner, R., Ainsworth, E.A., Bernacchi, C.J., Ort, D.R. 2016. Intensifying drought eliminates the expected benefits of elevated [CO2] for soybean. Nature Plants. 2:16132.

Interpretive Summary: This study investigated the interaction of drought stress and elevated [CO2] on soybean productivity. Although it was expected that elevated [CO2] would benefit soybean to a greater extent with increasing drought stress, this was not observed in the long-term study. Elevated [CO2] resulted in lower stomatal conductance and greater soil moisture in some years, but in years with greater drought stress, plants grown at elevated [CO2] had greater sensitivity to soil drying, impaired ntirogen fixation and less soil moisture available. Thus, as drought stress increased in intensity, the beneficial effects of elevated [CO2] were diminished. Hotter and dryer growing conditions are forecast for the future, and this study showed that elevated [CO2] will not protect soybean from these detrimental conditions.

Technical Abstract: Stimulation of C3 crop yield by rising [CO2] is widely expected to counteract crop losses to greater drought this century. But these expectations come from sparse field trials that have been biased towards mesic growth conditions. This eight-year study used precipitation manipulations and year-to-year variation in weather conditions at a unique open-air field facility to show that the stimulation of soybean yield by elevated [CO2] diminished to zero as drought intensified. Contrary to the prevalent expectation in the literature, rising [CO2] did not counteract the effect of strong drought on photosynthesis and yield because elevated [CO2] interacted with drought to modify stomatal function and canopy energy balance. This new insight from field experimentation under hot and dry conditions, which will become increasingly prevalent in the coming decades, highlights the likelihood of negative impacts from interacting global change factors on a key global commodity crop in its primary region of production.