A. Ylimartimo et al., UNBALANCED NUTRIENT STATUS AND EPICUTICULAR WAX OF SCOTS PINE NEEDLES, Canadian journal of forest research, 24(3), 1994, pp. 522-532
Different combinations of normal and excessive foliar levels of nitrog
en and normal and deficient foliar levels of K, Mg, and Ca were induce
d in Scots pine (Pinus sylvestris L.) seedlings in an experiment with
a completely randomized 2(4) factorial design during the growing seaso
n in 1991 and 1992. For scanning electron microscope analysis of epicu
ticular wax, the needles were sampled from the same part of the shoot
on the same seedlings in September 1991 and 1 year later. The quantity
and quality of the structural epicuticular wax were estimated by five
-class scales based on the wax coverage or morphology. The effects of
foliar nutrients on the quantity and quality of the wax were analyzed
by logistic models. The deleterious effect of unbalanced nutrition fir
st became visible in the stomatal furrows; the changes in wax coverage
and morphology were clear already one growing season after the start
of the nutrient treatments. Changes in the epistomatal chambers did no
t become discernible until 1 year later. The effect of different nutri
ents on the wax was somewhat different in stomatal and in nonstomatal
areas. Deficiencies of Ca and Mg significantly decreased wax coverage
in both the stomatal furrows and epistomatal chambers of the needles.
Coverage in the epistomatal chambers was also significantly decreased
by K deficiency, N excess, and consequently increased N/K ratios. The
wax morphology in both the stomatal furrows and epistomatal chambers c
hanged from tubelike to more fused and netlike structures as a result
of deficiencies of K, Mg, and Ca and consequently increased N/K, N/Mg,
and N/Ca ratios.