Growth rhythm and frost hardiness dynamics in Norway spruce (Picea abies (L.) Karst.)Westin, Johan
The seasonal growth rhythm and frost hardiness development of Norway spruce (Picea abies (L.) Karst.) in Northern Sweden were characterised in trees from local seed sources and transferred seed sources of natural and selected origins. The main aim was to clarify whether the growth performance of selected populations of local origin had a similar physiological basis to the growth performance of southern natural populations.
Populations of southern origins tended to initiate growth and dehardening later in spring, and start growth cessation and hardening later in autumn, than populations of northern origins. Populations transferred more than approximately 3 deg in latitude showed poor growth performances due to lower numbers of stem-units. Southern populations showed prolonged apical mitotic activity compared with those of northern and local origins.
Progenies of selected plus-trees showed a later start of growth and slightly later dehardening in spring. Growth cessation occurred later in juvenile seedlings of selected populations than in natural populations of similar origin. Furthermore, in non-juvenile trees of selected populations prolonged mitotic activity was observed. Needle frost hardiness levels in selected populations were similar to those of natural populations of similar origin. Selected populations of northern origins tended to produce more stem-units than natural populations of similar origin.
Throughout the studies, variation in duration of mitotic activity appeared to be unrelated to the number of stem-units produced. This was evident both among populations and among clones of similar origins. Furthermore, variation in the ability to produce stem-units could not explain variation in accumulated height growth among natural populations. Growth and hardiness performances of southern populations and of selected populations of local origin appeared, at least in part, to have a similar physiological basis i.e. delayed spring and autumn phenology.
Keywordsbuds; frost hardiness; growth; mitotic activity; needles; Norway spruce; Picea abies; stem units
Published inActa Universitatis Agriculturae Sueciae. Silvestria
2000, number: 125
Publisher: Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
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