DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/1966 str. 59     <-- 59 -->        PDF

For the selection of a character — which by its phenotype will provide
information on the gene pool of the populations of a species, the following
criteria are significant:


1) genetic (hereditary) relationship;


2) economic significance.


The genetic relationship, i.e. the degree of inheritance, is important because
it expresses the reality of phenotypic values. The degree of inheritance specifies
a portion of the total variability which can be ascribed to genetic causes (Lus h
1937). With the decrease of inheritance, the environment exercises an ever-
increasing influence on the manifestaticn and variation of a character. Thus
the gene pool of natural populations can be studied primarily on the basis of
the phenotypical expression of those characters that are of a high degree of
inheritance. The degree of inheritance of the characters is determined from
the parent-prcgeny regression, the sib analysis, then from well designed
provenance and clone tests, and by determining the proportion of genetic and
phenotypic variances (Lerner 1958; Falconer 1960; To da 1963; H a ttemer
1963).


It seems useful to study the gene pool of nature! forests on the basis of
the phenotypical expression of those genetically related characters that have
an economic significance. However, the genetic variability of many species has
often been studied in the past only from the botanical-systematical standpoint
on the basis of differences in taxonomical features not having in most cases
any economic significance. Despite this, we may consider these studies very
significant, because the taxonomic features are usually genetically closely
related qualities often correlated with morphological characteristics, (e.g. stem
form, branching, bark). Many of these qualities are of prime economic importance.
Therefore races separated according to taxonomic characteristics are
usualy also significant from the economicsilvicultural standpoint.


At any rate, it is useful to study the gene pool on the basis of the characters
of economic importance. Schreine r (1958) ranks in the following order
such genetically related characters:


1. Small quantity of branches; elimination of frost shakes, dormant buds,
of torsion of fibres; small fibril angle; fibre length and other anatomical
characteristics;
2. Stem form, cylindricity, branch thickness, angle of insertion of branches,
causative agents of stem deformation;
3. Height and diameter growth, distance between nodes or branches,
specific gravity, reaction wood, chemical composition of wood, mechanical
properties of wood.
The above ordinal numbers signify;


1 — very high degree of genetic control;


2 — high degree of genetic control, and


3 — moderately high degree of genetic control.


A number of important characters of physiological nature are omitted
from this list. These characters are subject to genetic control of a moderate to
high degree, such as: resistance to diseases, rootability of cuttings, transplantation
tolerance.


It should not by forgotten, however, that today we are not able to predict
the economic importance of many characters in the future. Such qualities as