title: Tree age dependence and within-canopy variation of leaf gas exchange and antioxidative defence in Fagus sylvatica under experimental free-air ozone exposure.
abstract: We characterized leaf gas exchange and antioxidative defence of two-year-old seedlings and 60-year-old trees of Fagus sylvatica exposed to ambient (1 x O3) or two-fold ambient (2 x O3) O3 concentrations (maximum of 150 ppb) in a free-air canopy exposure system throughout the growing season. Decline in photosynthesis from sun-exposed to shaded conditions was more pronounced in adult than juvenile trees. Seedling leaves and leaves in the sun-exposed canopy had higher stomatal conductance and higher internal CO2 concentrations relative to leaves of adult trees and leaves in shaded conditions. There was a weak overall depression of photosynthesis in the 2 x O3 variants across age classes and canopy positions. Pigment and tocopherol concentrations of leaves were significantly affected by canopy position and tree age, whereas differences between 1 x O3 and 2 x O3 regimes were not observed. Glutathione concentrations were significantly increased under 2 x O3 across both age classes and canopy levels. Seedlings differed from adult trees in relevant physiological and biochemical traits in ozone response. The water-soluble antioxidative systems responded most sensitively to 2 x O3 without regard of tree age or canopy position.
authors.affiliation: Institut für Pflanzenwissenschaften, Universität Graz, Schubertstrasse 51, A-8010 Graz, Austria. karin.herbinger@uni-graz.at
authors.forename: K
authors.initials: K
authors.lastname: Herbinger
authors.forename: Ch
authors.initials: Ch
authors.lastname: Then
authors.forename: M
authors.initials: M
authors.lastname: Löw
authors.forename: K
authors.initials: K
authors.lastname: Haberer
authors.forename: M
authors.initials: M
authors.lastname: Alexous
authors.forename: N
authors.initials: N
authors.lastname: Koch
authors.forename: K
authors.initials: K
authors.lastname: Remele
authors.forename: C
authors.initials: C
authors.lastname: Heerdt
authors.forename: D
authors.initials: D
authors.lastname: Grill
authors.forename: H
authors.initials: H
authors.lastname: Rennenberg
authors.forename: K-H
authors.initials: KH
authors.lastname: Häberle
authors.forename: R
authors.initials: R
authors.lastname: Matyssek
authors.forename: M
authors.initials: M
authors.lastname: Tausz
authors.forename: G
authors.initials: G
authors.lastname: Wieser
mesh_terms: D000064:Acclimatization; D000393:Air Pollutants / Q000633:toxicity*; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000032:analysis; D002245:Carbon Dioxide; D004463:Ecology / Q000379:methods; D004787:Environmental Pollution / Q000009:adverse effects*; D029964:Fagus / Q000254:growth & development* / Q000378:metabolism; D005978:Glutathione / Q000032:analysis; D010126:Ozone / Q000633:toxicity*; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism*; D018526:Plant Transpiration; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D000975:Antioxidants; D002245:Carbon Dioxide; D010126:Ozone; D005978:Glutathione; D001205:Ascorbic Acid