J. Hakulinen et al., DOES NITROGEN-FERTILIZATION HAVE AN IMPACT ON THE TRADE-OFF BETWEEN WILLOW GROWTH AND DEFENSIVE SECONDARY METABOLISM, Trees, 9(4), 1995, pp. 235-240
The effect of nitrogen fertilization on the phytomass production, shoo
t length and leaf secondary phenolics in nine Salix myrsinifolia clone
s was investigated. Cuttings taken from 1-year-old and 2-year-old shoo
t parts of field cultivated clones were grown at three concentrations
of nitrogen (7, 150 and 300 ppm) in a greenhouse for one growing seaso
n. The willow clones differed significantly in phytomass yield and sec
ondary phenolics content. Nitrogen fertilization affected significantl
y the growth and secondary metabolism of willow clones. In most clones
, the addition of nitrogen from a sub-optimum concentration (7 ppm) to
an optimum concentration (150 ppm) appeared to reduce the amounts of
salicortin, chlorogenic acid and unknown salicylate and increased shoo
t phytomass, but a supra-optimum nitrogen concentration (300 ppm) resu
lted in highly variable growth and secondary phenolic responses. A sig
nificantly negative correlation between leaf phytomass and amount of t
otal phenolics at sub-optimum and optimum N-treatments indicates trade
-off between growth and secondary metabolism in willow clones at these
treatments. However, the leaf phytomass:total amount of phenolics rat
io varied significantly among clones, and in all clones it was not sig
nificantly lower at sub-optimum N-treatment than at optimum N-treatmen
t.