Skógræktarritið - 15.05.2001, Side 190

SKÓGRÆKT HANDAN SKÓGARMARKA / NSSE
BRYNIAR SKÚLASON, AÐALSTEINN
SIGURGEIRSSON, BJARNI E. GUÐLEIFSSON
AND 0YVIND MELAND EDVARDSEN
Frost tolerance among
provenances and families from
the Picea complex in Alaska
SAMANTEKT
Af þeim trjátegundum sem ræktaðareru á íslandi eru mestarvonir
bundnar við sitkagreni sem timburtré á Suður- og Vesturlandi.
Reynslan er þó sú að sitkagreni verður á ungaaldri fyrir frostskemmd-
um bæði vor og haust. Til að kanna breytileikan á frostþoli milli greni-
tegunda, milli kvæma og milli afkvæmahópa innan kvæma voru frost-
þolspróf framkvæmd á samtals 8000 plöntum vor og haust. Hvítgreni-
og sitkabastarðskvæmi reyndust viðkvæmari fyrir vorfrostum en sit-
kagrenikvæmin, en sitkagrenið aftur viðkvæmara fyrir haustfrostum.
Mikill munurvará milli afkvæmahópa innan kvæma, sem bendirtil
þess að hægt sé að finna efnivið sem er sæmilega frostþolinn bæði
vor og haust. Samræmi var milli niðurstaðna frostþolsprófanna og
skemmda sem urðu í gróðrarstöð haustið áður. Líklegt er að hægt sé
að nota frostþolspróf við skamval á efniviði til notkunar í skógrækt.
Introduction
Sitka spruce (Picea sitchensis (Bong.)
Carr.) is the most promising tree
species for production forestry in
the cool, oceanic regions of
southern and western lceland.
Experience suggests, however,
that the species is susceptible to
frost damage during late spring
and early autumn. Genetic varia-
tion in growth rhythm and frost
hardiness in spring and autumn
among those provenances of
Sitka spruce that can be success-
fully grown under lcelandic condi-
tions was examined with the aim
of reducing fost damage.
Freeze testing under controlled
conditions was carried out on a
total of 8000 Sitka spruce and
Lutz spruce (Picea x liitzii) seed-
lings, from among 10 families
from each of 20 provenances.
Differences in frost tolerance
during spring and autumn were
significant among provenances
and among families within pro-
venances. Provenances of white
spruce (Picea glauca ((Moench)
Voss) and Lutz spruce were more
susceptible to damage from
spring frosts than those of Sitka
spruce. The converse was howev-
er true for autumn frost damage,
where damage was greatest in
Sitka spruce. Correlations
between frost tolerance and lati-
tude, longitude and elevation at
origin, as well as seedling height
were not significant. There was
however a strong and significant
relationship between damage
observed among provenances
and families in the nursery one
year earlier, attributed to autumn
frosts, and damages observed
after controlled freezing condi-
tions in the following autumn.
These results suggest the oppor-
tunity for using freeze testing for
early seleetion for frost hardiness
in the nursery and in the field.
Frost damage to seedlings in
lceland
Fall frost damage to Sitka spruce
seedlings is a considerable prob-
lem in lceland, occurring almost
every year in some regions, both
in nurseries and during the first
few years after outplanting.
Spring frost damage is less com-
mon but can be more severe
when it happens.
The main goals of this reaserch
were:
• To test the variability in spring
and fall frost hardiness among
half-sib. families within prove-
nances.
• To test the variabíIity in spring
and fall frost hardiness among
provenances.
• To test the effect of introgres-
sion between Sitka and white
spruce on dehardening in
spring and inwintering in fall.
• To test the possibility of using
frost hardiness testing in early
selection of hardy prove-
nances and families of Sitka
spruce.
Material and methods
A large spruce seed collection
took place in Alaska in 1987-1988.
This material has been planted in
several places in Norway,
Sweden, Finland and Iceland. A
large proportion of this material
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