title: Impacts of drought on leaf respiration in darkness and light in Eucalyptus saligna exposed to industrial-age atmospheric CO₂ and growth temperature.
abstract: Our study assessed the impact of a wide range of industrial-age climate scenarios on leaf respiration (R) in Eucalyptus saligna. Well-watered or sustained drought-treated plants were grown in glasshouses differing in atmospheric CO₂ concentration ([CO₂]) (280, 400 and 640 μl l⁻¹) and temperature (26 and 30°C). Rates of R in darkness (R(dark) ) and light (R(light) ), photosynthesis (A) and related leaf traits (mass : area relationships, and nitrogen, phosphorus, starch and sugar concentrations) were measured. Light inhibited R in all cases (R(light) < R(dark) ) (well-watered: 40%; drought-treated: 73%). Growth [CO₂] and temperature had little impact on area-based rates of R(dark) or R(light) , with R(light) exhibiting minimal thermal acclimation. By contrast, sustained drought resulted in reduced R(dark), R(light) and A, with the inhibitory effect of drought on A and R(light) (c. 50-70%) greater than that on R(dark) (c. 15%). Drought effects were fully reversible after watering. Variability in R(light) appeared to be dependent on the underlying rate of R(dark) and associated Rubisco activity. Collectively, our data suggest that there is an asynchronous response of leaf carbon metabolism to drought, and a tighter coupling between R(light) and A than between R(dark) and A, under both past and future climate scenarios. These findings have important implications for ecosystem/global models seeking to predict carbon cycling.
authors: Plant Sciences Division, Research School of Biology, Building 46, The Australian National University, Canberra, ACT 0200, Australia.
authors: Gohar
authors: G
authors: Ayub
authors: Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, NSW 2753, Australia.
authors: Renee A
authors: RA
authors: Smith
authors: Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, NSW 2753, Australia.
authors: David T
authors: DT
authors: Tissue
authors: Plant Sciences Division, Research School of Biology, Building 46, The Australian National University, Canberra, ACT 0200, Australia.
authors: Owen K
authors: OK
authors: Atkin
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000032:analysis*; D019069:Cell Respiration; D057231:Climate Change; D003624:Darkness; D055864:Droughts; D005052:Eucalyptus / Q000378:metabolism*; D008027:Light; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013213:Starch / Q000032:analysis; D013696:Temperature; D014867:Water
chemical_list: D002241:Carbohydrates; D014867:Water; D002245:Carbon Dioxide; D010758:Phosphorus; D002244:Carbon; D013213:Starch; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen