title: The influence of enhanced UV-B radiation on Batrachium trichophyllum and Potamogeton alpinus -- aquatic macrophytes with amphibious character.
abstract: The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to different UV-B environments were studied. Plant material from natural environments, as well as from outdoor treatments was examined. In long-term outdoor experiments plants were grown under three different levels of UV-B radiation: reduced and ambient UV-B levels, and a UV-B level simulating 17% ozone depletion. The following parameters were monitored: contents of total methanol soluble UV-absorbing compounds and chlorophyll a, terminal electron transport system (ETS) activity and optimal and effective quantum yield of photosystem II. No effect of the different UV-B levels on the measured parameters was observed. The amount of UV-B absorbing compounds seems to be saturated, since no differences were observed between treatments and no increase was found in peak season, when natural UV-B levels were the highest. Physiological measurements revealed no harmful effects; neither on potential and actual photochemical efficiency, nor on terminal ETS activity. The contents of UV-B absorbing compounds were examined also in plant material sampled in low and high altitude environments during the growth season. Both species exhibited no seasonal dynamics of production of UV-absorbing compounds. The contents were variable and showed no significant differences between high and low altitude populations.
authors.affiliation: National Institute of Biology, Vecna pot 111, Ljubljana, Slovenia. alenka.gaberscik@uni-lj.si
authors.forename: Mateja
authors.initials: M
authors.lastname: Germ
authors.forename: Zdenka
authors.initials: Z
authors.lastname: Mazej
authors.forename: Alenka
authors.initials: A
authors.lastname: Gaberscik
authors.forename: Donat P
authors.initials: DP
authors.lastname: Häder
mesh_terms: D002734:Chlorophyll / Q000378:metabolism / Q000528:radiation effects*; D000077194:Chlorophyll A; D004579:Electron Transport; D019684:Magnoliopsida / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A