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ŠUMARSKI LIST 3-4/1956 str. 36     <-- 36 -->        PDF


With this article the author wants to describe the possibilities of the application
of genetics in forestry and the methods which can be used in forest tree breeding.

It is important in forest tree breeding to know the systematical units and proveniences
within the species, and the distribution of these systematical units. Phytosociological
units (types) are of importance for the more complete knowledge of
the biology of forest trees and therefore for the forest tree breeder. If these details
are known, then the work of forest tree breeding will be easier and many time-
consuming mistakes avoided.

Good material must in the first instance be selected. This selection of the trees
has to be very carefully done because of the influence of the environmental factors
on the growth of the trees. It is possible by establishing the genotype to investigate
the influence of the environmental factors on the tree characters.

One of the main works of forest tree breeding is to get better seed sources.
We can get good seed material by gathering the seed from the best trees of determined
provenances. Itf such trees are vegetatively propagated the new individuals
will in a short time be able to supply us with seed, and artificial pollination with
such low tress is easier. In such a way we can get seed of improved quality. Seed
production can also be done in seed orchards with free pollination. The trees for
the seed orchards must be produced vegetatively in order to get early flowering.
Seed production in a seed orchard is cheaper and more simple than seed produced
by artificial pollination. Therefore it is important to study flowering and methods
of vegetative propagation.

By using artificial pollination we are able to control the offspring. When crossing
is made within a species or genus we sometimes get hybrid vigor. In this
way it is possible to get new types with Improved quality. By means of controlled
cross-pollination between trees of one or two species with different good characteristics
we are at times able to get a hybrid which has both of the good characteristics;
for example, the hybrid made by C. Syrach Larsen European and Japanese
larch which is not attacked severely by the larch canker and has good growth
form from the European larch together with hybrid vigor. B. Soegaard has by
cross-pollination between Thuja plicata and Thuja Standishii got a hybrid which
is resistant against attack by the fungus Didymascella thujina.

Polyploid plants sometimes grow better than the diploid. It can therefore be
of value to do chromosome testing. The triploid Populus tremula is an example
for this.

It is also possible to get polyploid plants in an artificial way by using X rayi,,
colchicine, and shock temperature.

Acclimatisation can be used in forest tree breeding by introducing trees from
one locality to another with different growth conditions. As an example, Pinus
radiata which in its native habitat, California, is a rather poor tree but which
has shown a remarkable growth improvement in South Africa, Australia and
New Zealand.

By means forest tree breeding it is possible for us to improve our forests. We
therefore must pay attention to this field of the forestry science.