title: Leaf respiration in darkness and in the light under pre-industrial, current and elevated atmospheric CO₂ concentrations.
abstract: Our study sought to understand how past, low atmospheric CO2 concentrations ([CO2]) impact respiration (R) of soybean (Glycine max), when compared to plants grown under current and future [CO2]s. Experiments were conducted using plants grown under 290, 400 and 700 ppm [CO2]. Leaf R was measured in both darkness (RD) and in the light (RL; using the Kok method), with short-term changes in measurement [CO2] and [O2] being used to explore the relationship between light inhibition of leaf R and photorespiration. Root R, photosynthesis (A), leaf [N] and biomass allocation traits were also quantified. In contrast to the inhibitory effect of low growth [CO2] on A, growth [CO2] had no significant effect on leaf RD or root R. Irrespective of growth [CO2], RL was always lower than RD, with light inhibiting leaf R by 17-47%. Importantly, the degree of light inhibition of leaf R was lowest in plants grown under low [CO2], with variations in RL being positively correlated with RD and photorespiration. Irrespective of whether leaf R was measured in the light or dark, a greater proportion of the carbon fixed by leaf photosynthesis was released by leaf R in plants grown under low [CO2] than under current/future [CO2]'s. Collectively, our results highlight the differential responses of A and R to growth of plants under low to elevated atmospheric [CO2].
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT 0200, Australia; Department of Biology, University of York, PO Box 373, York YO10 5YW, UK. Electronic address: gohar.ayub@aup.edu.pk.
authors.forename: Gohar
authors.initials: G
authors.lastname: Ayub
authors.affiliation: Department of Biology, University of York, PO Box 373, York YO10 5YW, UK; School of Geosciences, The University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK.
authors.forename: Joana
authors.initials: J
authors.lastname: Zaragoza-Castells
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: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT 0200, Australia; Department of Biology, University of York, PO Box 373, York YO10 5YW, UK; ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 0200, Australia. Electronic address: owen.atkin@anu.edu.au.
authors.forename: Owen K
authors.initials: OK
authors.lastname: Atkin
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism*; D019069:Cell Respiration; D003624:Darkness; D010100:Oxygen; D010788:Photosynthesis; D018515:Plant Leaves / Q000033:anatomy & histology / Q000737:chemistry / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D013025:Glycine max
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: Climate change; Kok effect; Photorespiration; Photosynthesis; Respiration; Soybean