title: Phosphorus application and elevated CO2 enhance drought tolerance in field pea grown in a phosphorus-deficient vertisol.
abstract: OBJECTIVE
  Benefits to crop productivity arising from increasing CO2 fertilization may be offset by detrimental effects of global climate change, such as an increasing frequency of drought. Phosphorus (P) nutrition plays an important role in crop responses to water stress, but how elevated CO2 (eCO2) and P nutrition interact, especially in legumes, is unclear. This study aimed to elucidate whether P supply improves plant drought tolerance under eCO2.
  
  
  METHODS
  A soil-column experiment was conducted in a free air CO2 enrichment (SoilFACE) system. Field pea (Pisum sativum) was grown in a P-deficient vertisol, supplied with 15 mg P kg(-1) (deficient) or 60 mg P kg(-1) (adequate for crop growth) and exposed to ambient CO2 (aCO2; 380-400 ppm) or eCO2 (550-580 ppm). Drought treatments commenced at flowering. Measurements were taken of soil and leaf water content, photosynthesis, stomatal conductance, total soluble sugars and inorganic P content (Pi).
  
  
  RESULTS
  Water-use efficiency was greatest under eCO2 when the plants were supplied with adequate P compared with other treatments irrespective of drought treatment. Elevated CO2 decreased stomatal conductance and transpiration rate, and increased the concentration of soluble sugars and relative water contents in leaves. Adequate P supply increased concentrations of soluble sugars and Pi in drought-stressed plants. Adequate P supply but not eCO2 increased root length distribution in deeper soil layers.
  
  
  CONCLUSIONS
  Phosphorus application and eCO2 interactively enhanced periodic drought tolerance in field pea as a result of decreased stomatal conductance, deeper rooting and high Pi availability for carbon assimilation in leaves.
authors.affiliation: Centre for AgriBioscience, La Trobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia and.
authors.forename: Jian
authors.initials: J
authors.lastname: Jin
authors.affiliation: Centre for AgriBioscience, La Trobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia and.
authors.forename: Dominic
authors.initials: D
authors.lastname: Lauricella
authors.affiliation: Department of Environment and Primary Industries, PMB 260 Horsham, Victoria 3401, Australia.
authors.forename: Roger
authors.initials: R
authors.lastname: Armstrong
authors.affiliation: Centre for AgriBioscience, La Trobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia and.
authors.forename: Peter
authors.initials: P
authors.lastname: Sale
authors.affiliation: Centre for AgriBioscience, La Trobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia and C.Tang@latrobe.edu.au.
authors.forename: Caixian
authors.initials: C
authors.lastname: Tang
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology*; D002980:Climate; D055864:Droughts; D018532:Pisum sativum / Q000187:drug effects / Q000502:physiology*; D010758:Phosphorus / Q000172:deficiency / Q000494:pharmacology*; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D012987:Soil; D014867:Water / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D010758:Phosphorus
keywords: Climate change; FACE; P nutrition; Pisum sativum; crop nutrition; drought tolerance; free air CO2 enrichment; pea; root length distribution; stomatal conductance; water-use efficiency