title: Soybean leaf hydraulic conductance does not acclimate to growth at elevated [CO2] or temperature in growth chambers or in the field.
abstract: OBJECTIVE
  Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased temperature compared with the responses of leaf gas exchange and leaf water status.
  
  
  METHODS
  Two controlled-environment growth chamber experiments were conducted with soybean to measure Kleaf, stomatal conductance (gs) and photosynthesis (A) during growth at elevated [CO2] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO2] (FACE) and canopy warming.
  
  
  RESULTS
  In chamber studies, Kleaf did not acclimate to growth at elevated [CO2], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect Kleaf, although gs and A showed significant but inconsistent decreases. The lack of response of Kleaf to growth at increased [CO2] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility.
  
  
  CONCLUSIONS
  Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although gs responded to [CO2] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change.
authors.affiliation: Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Locke
authors.forename: Lawren
authors.initials: L
authors.lastname: Sack
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Bernacchi
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ort
mesh_terms: D000064:Acclimatization; D002245:Carbon Dioxide / Q000378:metabolism*; D002980:Climate; D057231:Climate Change; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D013025:Glycine max / Q000254:growth & development / Q000502:physiology*; D013696:Temperature; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water; D002245:Carbon Dioxide
keywords: Glycine max; Leaf hydraulic conductance; climate change; elevated CO2; soybean; temperature; water potential