Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

• Published in: Environmental pollution (1987) 2010-04, Vol.158 (4), p.992-999
• Main Authors: Noormets, Asko, Kull, Olevi, Sôber, Anu, Kubiske, Mark E, Karnosky, David F
• Format: Article
• Language: English
• Subjects: Acclimation; Air Pollutants - toxicity; air pollution; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Canopies; Carbon dioxide; Carbon Dioxide - metabolism; carboxylation; chlorophyll; Dose-Response Relationship, Drug; Ecotoxicology, biological effects of pollution; electron transfer; Electron Transport - drug effects; Elevated; elevated atmospheric gases; Flux; forest trees; Fundamental and applied biological sciences. Psychology; General aspects; leaves; nitrogen content; ozone; Ozone - metabolism; Ozone - toxicity; Photons; Photosynthesis; Photosynthesis - drug effects; Plant Leaves - metabolism; Populus - drug effects; Populus - growth & development; Populus - metabolism; Populus tremuloides; Tolerances
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2009.10.009

The effect of elevated CO2 and O3 on apparent quantum yield (), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus tremuloides) clones of contrasting O3 tolerance. Local light climate at every leaf was characterized as fraction of above-canopy photosynthetic photon flux density (ÆPPFD). Elevated CO2 alone did not affect or Pmax, and increased Jmax in the O3-sensitive, but not in the O3-tolerant clone. Elevated O3 decreased leaf chlorophyll content and all photosynthetic parameters, particularly in the lower canopy, and the negative impact of O3 increased through time. Significant interaction effect, whereby the negative impact of elevated O3 was exaggerated by elevated CO2 was seen in Chl, N and Jmax, and occurred in both O3-tolerant and O3-sensitive clones. The clonal differences in the level of CO2 × O3 interaction suggest a relationship between photosynthetic acclimation and background O3 concentration. Photosynthetic acclimation to elevated CO2 depends on the background oxidant levels.