Rising ozone concentrations decrease soybean evapotranspiration and water use efficiency whilst increasing canopy temperature

Authors

  • Andy VanLoocke,

    1. Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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  • Amy M. Betzelberger,

    1. Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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  • Elizabeth A. Ainsworth,

    1. Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
    2. Global Change and Photosynthesis Research Unit, United States Department of Agriculture Agricultural Research Service, Urbana, IL 61801, USA
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  • Carl J. Bernacchi

    1. Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
    2. Global Change and Photosynthesis Research Unit, United States Department of Agriculture Agricultural Research Service, Urbana, IL 61801, USA
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Author for correspondence:
Carl J. Bernacchi
Tel: +1 217 333 8048
Email: bernacch@illinois.edu

Summary

  • Here, we investigated the effects of increasing concentrations of ozone ([O3]) on soybean canopy-scale fluxes of heat and water vapor, as well as water use efficiency (WUE), at the Soybean Free Air Concentration Enrichment (SoyFACE) facility.
  • Micrometeorological measurements were made to determine the net radiation (Rn), sensible heat flux (H), soil heat flux (G0) and latent heat flux (λET) of a commercial soybean (Glycine max) cultivar (Pioneer 93B15), exposed to a gradient of eight daytime average ozone concentrations ranging from approximately current (c. 40 ppb) to three times current (c. 120 ppb) levels.
  • As [O3] increased, soybean canopy fluxes of λET decreased and H increased, whereas Rn and G0 were not altered significantly. Exposure to increased [O3] also resulted in warmer canopies, especially during the day. The lower λET decreased season total evapotranspiration (ET) by c. 26%. The [O3]-induced relative decline in ET was half that of the relative decline in seed yield, driving a 50% reduction in seasonal WUE.
  • These results suggest that rising [O3] will alter the canopy energy fluxes that drive regional climate and hydrology, and have a negative impact on productivity and WUE, key ecosystem services.

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