Ambient UV-B radiation reduces PSII performance and net photosynthesis in high Arctic Salix arctica

Kristian Rost Albert, Teis Nørgaard Mikkelsen, Helge Ro-Poulsen, Marie F. Arndal, Anders Michelsen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Ambient ultraviolet-B (UV-B) radiation potentially impacts the photosynthetic performance of high Arctic plants. We conducted an UV-B exclusion experiment in a dwarf shrub heath in NE Greenland (74°N), with open control, filter control, UV-B filtering and UV-AB filtering, all in combination with leaf angle control. Two sites with natural leaf positions had ground angles of 0° (‘level site’) and 45° (‘sloping site’), while at a third site the leaves were fixed in an angle of 45° to homogenize the irradiance dose (‘fixed leaf angle site’). The photosynthetic performance of the leaves was characterized by simultaneous gas exchange and chlorophyll fluorescence measurements and the PSII performance through the growing season was investigated with fluorescence measurements. Leaf harvest towards the end of the growing season was done to determine the specific leaf area and the content of carbon, nitrogen and UV-B absorbing compounds. Compared to a 60% reduced UV-B irradiance, the ambient solar UV-B reduced net photosynthesis in Salix arctica leaves fixed in the 45° position which exposed leaves to maximum natural irradiance. Also a reduced Calvin Cycle capacity was found, i.e. the maximum rate of electron transport (Jmax) and the maximum carboxylation rate of Rubisco (Vcmax), and the PSII performance showed a decreased quantum yield and increased energy dissipation. A parallel response pattern and reduced PSII performance at all three sites indicate that these responses take place in all leaves across position in the vegetation. These findings add to the evidence that the ambient solar UV-B currently is a significant stress factor for plants in high Arctic Greenland.
    Original languageEnglish
    JournalEnvironmental and Experimental Botany
    Volume73
    Issue numberSI
    Pages (from-to)10-18
    ISSN0098-8472
    DOIs
    Publication statusPublished - Nov 2011

    Keywords

    • Environment and climate
    • JIP test
    • Photoinhibition
    • J(max)
    • UV-B exclusion
    • V-cmax
    • plant stress
    • Stomatal conductance

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