title: Thermal acclimation of leaf respiration but not photosynthesis in Populus deltoides x nigra.
abstract: Dark respiration and photosynthesis were measured in leaves of poplar Populus deltoides x nigra ('Veronese') saplings to investigate the extent of respiratory and photosynthetic acclimation in pre-existing and newly emerged leaves to abrupt changes in air temperature. The saplings were grown at three temperature regimes and at high and low nitrogen availabilities. Rates of photosynthesis and dark respiration (R(d)) were measured at the initial temperature and the saplings were then transferred to a different temperature regime, where the plants remained for a second and third round of measurements on pre-existing and newly emerged leaves. Acclimation of photosynthesis was limited following transfer to warmer or cooler growing conditions. There was strong evidence of cold and warm acclimation of R(d) to growth temperature, but this was limited in pre-existing leaves. Full acclimation of R(d )was restricted to newly emerged leaves grown at the new growth temperature. These findings indicate that the extent of thermal acclimation differs significantly between photosynthesis and respiration. Importantly, pre-existing leaves in poplar were capable of some respiratory acclimation, but full acclimation was observed only in newly emerged leaves. The R(d)/A(max) ratio declined at higher growth temperatures, and nitrogen status of leaves had little impact on the degree of acclimation.
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
authors.forename: Lai Fern
authors.initials: LF
authors.lastname: Ow
authors.affiliation: Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964-8000, USA.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Griffin
authors.affiliation: Landcare Research, PO Box 40, Lincoln 7640, New Zealand.
authors.forename: David
authors.initials: D
authors.lastname: Whitehead
authors.affiliation: Landcare Research, Private Bag 11052, Manawatu Mail Centre, Palmerston North 4442, New Zealand.
authors.forename: Adrian S
authors.initials: AS
authors.lastname: Walcroft
authors.affiliation: School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Turnbull
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D019069:Cell Respiration / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism*; D032107:Populus / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D009584:Nitrogen