title: Diverging temperature responses of CO2 assimilation and plant development explain the overall effect of temperature on biomass accumulation in wheat leaves and grains.
abstract: There is a growing consensus in the literature that rising temperatures influence the rate of biomass accumulation by shortening the development of plant organs and the whole plant and by altering rates of respiration and photosynthesis. A model describing the net effects of these processes on biomass would be useful, but would need to reconcile reported differences in the effects of night and day temperature on plant productivity. In this study, the working hypothesis was that the temperature responses of CO2assimilation and plant development rates were divergent, and that their net effects could explain observed differences in biomass accumulation. In wheat (Triticum aestivum) plants, we followed the temperature responses of photosynthesis, respiration and leaf elongation, and confirmed that their responses diverged. We measured the amount of carbon assimilated per "unit of plant development" in each scenario and compared it to the biomass that accumulated in growing leaves and grains. Our results suggested that, up to a temperature optimum, the rate of any developmental process increased with temperature more rapidly than that of CO2assimilation and that this discrepancy, summarised by the CO2assimilation rate per unit of plant development, could explain the observed reductions in biomass accumulation in plant organs under high temperatures. The model described the effects of night and day temperature equally well, and offers a simple framework for describing the effects of temperature on plant growth.
authors.affiliation: Australian Centre for Plant Functional Genomics, University of Adelaide, School of Agriculture Food and Wine, Hartley Grove, Urrbrae, South Australia 5064, Australia.
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Collins
authors.affiliation: Australian Centre for Plant Functional Genomics, University of Adelaide, School of Agriculture Food and Wine, Hartley Grove, Urrbrae, South Australia 5064, Australia boris.parent@supagro.inra.fr.|Current address: INRA, UMR759 Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux. Place Viala, F-34060 Montpellier, France boris.parent@supagro.inra.fr.|boris.parent@supagro.inra.fr; iman.lohraseb@acpfg.com.au; nick.collins@acpfg.com.au boris.parent@supagro.inra.fr.
authors.forename: Boris
authors.initials: B
authors.lastname: Parent
keywords: Biomass; development; grain growth; photosynthesis; respiration; specific leaf area; temperature; thermal time; wheat.