GENETIC-VARIATION IN CHARACTERS OF IMPORTANCE FOR STAND ESTABLISHMENTIN SITKA SPRUCE (PICEA-SITCHENSIS (BONG) CARR)

This paper summarizes the results of 2 series of clonal trials-F206 in cluding 151 clones and F215 including 196 clones. The characters measu red are: selection intensity for height growth in the nursery, height, autumn coloration, flushing, leader breaks, April-frost damage, and m ortality, all characters of expected importance for stand establishmen t. Genotype-environment interaction and correlation between characters are studied as well. Compared to the standard, a direct import from Q ueen Charlotte Islands, the clones, selected in a danish second genera tion material, have a superiority in height growth of 23% to 31%, fewe r leader damage, 16% to 17%, and less damage due to April-frost, score 1.1 to 2.5, whereas there is hardly no differences in flushing time a nd only minor differences in mortality, 1% to 5% less dead trees. Ther e is considerable variance among clones for April-frost damage, but th e results are only based on one year. If the frost hits later in the s pring the differences between the clones will probably be less because they all are closer to the growing season and all will have an active cambium. Severe damage due to April-frost is a rather seldom event in Denmark. and one may question the effort to avoid damage by selecting less sensitive clones, unless it is an indirect gain by selecting for late flushing clones to late spring frost exposed sites, where even s mall differences in time of flashing will make a difference.There is o nly a very limited possibility to select for late flushing in spite of high heritability estimates. Autumn coloration shows no reasonable co rrelations to held damage and may not be an appropriate measure of aut umn hardening. Selection based on 3 year old cuttings yield about 63% to 77% of the results obtained by direct selection 5 years later in th e field. Concerning the ageing-problem of the hedges for cutting produ ction 3 year nursery results seem to be a reasonable basis to start co mmercial production of selected clones. Early selection of ortets amon g 3 or 4 year old seedlings for height growth seems not to be an appro priate way to increase height growth within the danish provenance. Gen eral problems with ageing of propagation material restricts the practi cal use of the clonal material. Clonal mean values of ecovalence as a stability measure is estimated for the characters showing genotype-env ironment interaction. Only a rather Limited number, around 15%, of the clones acounts for more than 50% of the genotype-environment interact ion sums of square.