Effects of UV-B treatment on the distribution of wax tubes of Scots pine needles

A UV-B experiment was conducted during two growing seasons in 1994–1995 in greenhouses in the University of Oulu, Finland. Biologically effective UV doses were 0 kJm−2d−1, 2.2–6.6 kJm−2d−1 and 5.6–16.8 kJm−2d−1. Grafted Scots pine clones from the Kola Peninsula and pine seedlings from Kittilä and Inari were used. Wax tube distribution on needles was studied under a SEM equipped with a phase-analysing system. Significant differences in wax tube coverage emerged between the provenances, but not between the treatments. Wax tube distribution ranged from 54–66% of the surface of the Kola Peninsula needles to 47–50% of the Kittilä and 27–36% of the Inari needles.