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Keywords:

  • Betula pendula;
  • birch;
  • exposure-response curves;
  • mineral nutrients;
  • relative nutrient addition rate;
  • secondary metabolites;
  • stratospheric ozone depletion;
  • UV-B radiation

Summary

  • • 
    Changes in secondary metabolites in silver birch ( Betula pendula ) seedlings are presented in response to ultraviolet-B radiation (UV-B) and nutrient addition.
  • • 
    Concentrations of individual secondary metabolites and nutrients were measured in leaves of greenhouse-grown silver birch seedlings exposed to five time-integrated irradiances of biologically effective UV-B (I BEUV-B ) and fertilized with two relative nutrient addition rates.
  • • 
    Several phenolics were not only induced by UV-B, but their concentration was dependent on UV-B daily time-integrated irradiance. Relative nutrient addition rate also affected the concentration of phenolics but had little effect on the UV-B daily time-integrated irradiance-responses. The mineral nutrient concentration of leaves was affected by nutrient addition but not by increasing I BEUV-B . Possible threshold-exposures for the accumulation of secondary metabolites or nutrients were not detected.
  • • 
    UV-B and relative nutrient addition rate have mainly an additive (rather than synergistic) effect in silver birch, and leaves respond to increasing UV-B by synthesizing metabolites (e.g. flavonols), which are important UV-B filters. This study reports the first UV-B-exposure-response curves for individual secondary metabolites and nutrients in leaves of a woody tree species.