title: Rising ozone concentrations decrease soybean evapotranspiration and water use efficiency whilst increasing canopy temperature.
abstract: • Here, we investigated the effects of increasing concentrations of ozone ([O(3)]) 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 (R(n)), sensible heat flux (H), soil heat flux (G(0)) 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 [O(3)] increased, soybean canopy fluxes of λET decreased and H increased, whereas R(n) and G(0) were not altered significantly. Exposure to increased [O(3)] also resulted in warmer canopies, especially during the day. The lower λET decreased season total evapotranspiration (ET) by c. 26%. The [O(3)]-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 [O(3)] will alter the canopy energy fluxes that drive regional climate and hydrology, and have a negative impact on productivity and WUE, key ecosystem services.
authors.affiliation: Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Andy
authors.initials: A
authors.lastname: VanLoocke
authors.forename: Amy M
authors.initials: AM
authors.lastname: Betzelberger
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Ainsworth
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Bernacchi
mesh_terms: D002980:Climate; D007087:Illinois; D010126:Ozone / Q000494:pharmacology; D018526:Plant Transpiration / Q000187:drug effects; D012621:Seasons; D012987:Soil; D013025:Glycine max / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D014867:Water
chemical_list: D012987:Soil; D014867:Water; D010126:Ozone