The sequence of change within the photosynthetic apparatus of wheat following short-term exposure to ozone. [Triticum aestivum L. cv Avalon]

Journal Article · Fri Feb 01 00:00:00 EST 1991 · Plant Physiology; (United States)

DOI:https://doi.org/10.1104/pp.95.2.529· OSTI ID:5928369

Farage, P K; Long, S P; Baker, N R ^[1]; Lechner, E G ^[2]

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1. Univ. of Essex (England)
2. Univ. of Vienna (Austria)

The basis of inhibition of photosynthesis by single acute O{sub 3} exposures was investigated in vivo using analyses based on leaf gas exchange measurements. The fully expanded second leaves of wheat plants (Triticum aestivum L. cv Avalon) were fumigated with either 200 or 400 nanomoles per mole O{sub 3} for between 4 and 16 hours. This reduced significantly the light-saturated rate of Co{sub 2} uptake and was accompanied by a parallel decrease in stomatal conductance. However, the stomatal limitation only increased significantly during the first 8 hours of exposure to 400 nanomoles per mole O{sub 3}; no significant increase occurred for any of the other treatments. Analysis of the response of CO{sub 2} uptake to the internal Co{sub 2} concentration implied that the predominant factor responsible for the reduction in light-saturated CO{sub 2} uptake was a decrease in the efficiency of carboxylation. At saturating concentrations of Co{sub 2}, photosynthesis was inhibited by no more than 22% after 16 hours, indicating that the capacity for regeneration of ribulose bisphosphate was less susceptible to O{sub 3}. Ozone fumigations also had a less pronounced effect on light-limited photosynthesis. The photochemical efficiency of photosystem II estimated from the ratio of variable to maximum chlorophyll fluorescence and the atrazine-binding capacity of isolated thylakoids demonstrated that photochemical reactions were not responsible for the initial inhibition of CO{sub 2} uptake.

• OSTI ID: 5928369
• Journal Information: Plant Physiology; (United States), Vol. 95:2; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
OZONE
TOXICITY
WHEAT
PHOTOSYNTHESIS
CARBON DIOXIDE
LEAVES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHETIC REACTION CENTERS
UPTAKE
CARBON COMPOUNDS
CARBON OXIDES
CEREALS
CHALCOGENIDES
CHEMICAL REACTIONS
GRAMINEAE
LILIOPSIDA
MAGNOLIOPHYTA
OXIDES
OXYGEN COMPOUNDS
PLANTS
SYNTHESIS
560300* - Chemicals Metabolism & Toxicology
551000 - Physiological Systems