PROVENANCE VARIATION IN SHOOT GROWTH COMPONENTS OF NORWAY SPRUCE

The elongation of terminal shoots was measured during 2 growth seasons in a Norway spruce (Picea abies (L.) KARST.) provenance trial, compri sing 36 provenances. Significant variation was found between provenanc e regions for traits that characterize the timing and duration of the growth period, but not for the rate of growth. Provenances from the No rdic countries terminated their growth 20 days earlier in the summer t han the provenances from Eastern Poland which had the latest growth ce ssation. The duration of the growth period accounted for the larger pa rt of the variation in shoot growth (80%) among provenances, while the rate of growth was an equally important factor within provenances. Th e day of growth cessation, the duration of the growth period and total annual shoot growth were closely correlated to altitude for provenanc es originating along an altitudinal gradient, but no such correlation was found between rate of growth and altitude. Within a provenance reg ion in southern Poland the variation among provenances was exclusively in the timing and duration of the growth period. In another region in the Baltic countries, variation in the rate of growth was equally imp ortant as its duration for determining total shoot growth.