Tree age dependence and within-canopy variation of leaf gas exchange and antioxidative defence in Fagus sylvatica under experimental free-air ozone exposure.
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.
Herbinger
K
K
Institut für Pflanzenwissenschaften, Universität Graz, Schubertstrasse 51, A-8010 Graz, Austria. karin.herbinger@uni-graz.at
Then
Ch
Ch
Löw
M
M
Haberer
K
K
Alexous
M
M
Koch
N
N
Remele
K
K
Heerdt
C
C
Grill
D
D
Rennenberg
H
H
Häberle
K-H
KH
Matyssek
R
R
Tausz
M
M
Wieser
G
G
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
D000393:Air Pollutants; D000975:Antioxidants; D002245:Carbon Dioxide; D010126:Ozone; D005978:Glutathione; D001205:Ascorbic Acid