Thermal acclimation of leaf respiration but not photosynthesis in Populus deltoides×nigra

Abstract

Summary• Dark respiration and photosynthesis were measured in leaves of poplar Populus deltoides × 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.

Interactive effect of elevated temperature and O3 on antioxidant capacity and gas exchange in Betula pendula saplings

“…O 3 as compared to T may indicate oxidative stress under the combination treatment. The decreased ratio between J max and V c,max under T indicate a greater activation energy for V c,max than for J max , and accords with other studies of elevated temperature (Onoda et al 2005;Ow et al 2008). …”

“…On the other hand, the enhanced supply of photosynthates may increase the ability of plants to up-regulate enzymatic antioxidative activity and formation of antioxidant compounds. However, acclimation of leaf metabolism and structure to long-term changes in temperature may reduce the magnitude of the responses such that plant performance will remain unaltered at a new growth temperature (Atkin and Tjoelker 2003;Kattge and Knorr 2007;Ow et al 2008). In Medicago sativa the total ascorbate concentration and redox state were generally lower in plants grown at elevated temperature (ambient ?4°C), especially under water limitation conditions (Erice et al 2007).…”

Growing season temperatures limit growth of loblolly pine (Pinus taeda L.) seedlings across a wide geographic transect

“…Thermal acclimation is a reversible, physiological change that enables optimum functioning of plants under different temperature regimes (Atkin and Tjoelker 2003). Thermal acclimation of respiration, which reduces the loss of carbon at higher temperatures and increases metabolic activity at lower temperatures, has been commonly observed in trees (Rook 1969;Paembonan et al 1991;Teskey and Will 1999;Bolstad et al 2003;Lee et al 2005;Ow et al 2008;Tjoelker et al 2008). Thermal acclimation of photosynthesis causes a shift in the temperature optimum that enhances carbon gain.…”

Responses of carbon dioxide flux and plant biomass to water table drawdown in a treed peatland in northern Alberta: a climate change perspective

“…Photosynthesis and autotrophic respiration may vary independently with changing temperature (Ryan, 1995;Ow et al, 2008). Warm and dry conditions in peatlands can either stimulate CO 2 uptake by enhanced GPP (e.g.…”