Secondary metabolites and nutrient concentrations in silver birch seedlings under five levels of daily UV-B exposure and two relative nutrient addition rates
Tm. De La Rosa et al., Secondary metabolites and nutrient concentrations in silver birch seedlings under five levels of daily UV-B exposure and two relative nutrient addition rates, NEW PHYTOL, 150(1), 2001, pp. 121-131
Changes in secondary metabolites in silver birch (Betula pendula) seedlings
are presented in response to ultraviolet-B radiation (UV-B) and nutrient a
ddition.
Concentrations of individual secondary metabolites and nutrients were measu
red in leaves of greenhouse-grown silver birch seedlings exposed to five ti
me-integrated irradiances of biologically effective UV-B (I-BE(UV-B)) and f
ertilized with two relative nutrient addition rates.
Several phenolics were not only induced by UV-B, but their concentration wa
s dependent on UV-B daily time-integrated irradiance. Relative nutrient add
ition rate also affected the concentration of phenolics but had little effe
ct on the UV-B daily time-integrated irradiance-responses. The mineral nutr
ient concentration of leaves was affected by nutrient addition but not by i
ncreasing I-BE(UV-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 th
an synergistic) effect in silver birch, and leaves respond to increasing UV
-B by synthesizing metabolites (e.g. flavonols), which are important UV-B f
ilters. This study reports the first UV-B-exposure-response curves for indi
vidual secondary metabolites and nutrients in leaves of a woody tree specie
s.