title: Stomatal characteristics and infection biology of Pyrenopeziza betulicola in Betula pendula trees grown under elevated CO2 and O3.
abstract: Two silver birch clones were exposed to ambient and elevated concentrations of CO(2) and O(3), and their combination for 3 years, using open-top chambers. We evaluated the effects of elevated CO(2) and O(3) on stomatal conductance (g(s)), density (SD) and index (SI), length of the guard cells, and epidermal cell size and number, with respect to crown position and leaf type. The relationship between the infection biology of the fungus (Pyrenopeziza betulicola) causing leaf spot disease and stomatal characteristics was also studied. Leaf type was an important determinant of O(3) response in silver birch, while crown position and clone played only a minor role. Elevated CO(2) reduced the g(s), but had otherwise no significant effect on the parameters studied. No significant interactions between elevated CO(2) and O(3) were found. The infection biology of P. betulicola was not correlated with SD or g(s), but it did occasionally correlate positively with the length of the guard cells.
authors.affiliation: Department of Ecology and Environmental Science, University of Kuopio, PO Box 1627, FIN-70211, Kuopio, Finland. johanna.riikonen@uku.fi
authors.forename: Johanna
authors.initials: J
authors.lastname: Riikonen
authors.forename: Leena
authors.initials: L
authors.lastname: Syrjälä
authors.forename: Ingmar
authors.initials: I
authors.lastname: Tulva
authors.forename: Pille
authors.initials: P
authors.lastname: Mänd
authors.forename: Elina
authors.initials: E
authors.lastname: Oksanen
authors.forename: Marja
authors.initials: M
authors.lastname: Poteri
authors.forename: Elina
authors.initials: E
authors.lastname: Vapaavuori
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D029662:Betula / Q000382:microbiology*; D002245:Carbon Dioxide / Q000633:toxicity*; D004463:Ecology / Q000379:methods; D005387:Finland; D017752:Greenhouse Effect; D009181:Mycoses; D010126:Ozone / Q000633:toxicity*; D010788:Photosynthesis; D019441:Plant Epidermis / Q000166:cytology / Q000187:drug effects; D018526:Plant Transpiration
chemical_list: D000393:Air Pollutants; D002245:Carbon Dioxide; D010126:Ozone