DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 1-2/1966 str. 170     <-- 170 -->        PDF

The established seed orchards commence to attract the interest of economic organizations
so that the establishement of operative seed orchards is expected soon.


4. Establishment of tree alleys for comparison
The first comparative clonal plantings were raised in 1948 by the Poplar Institute,
Novi Sad. The same Institute has laid out so far a total of 30 clonal test plantings
of Poplars from the section Aegeiros in which are being tested hundreds of
native and foreign clones. Besides, established were 3 tests with White Poplar and
15 tests with P. tremula x P. tremuloides hybrids. In the same way were laid out
15 tests with about 30 clones of Willows mostly indigenous and to a lesser extent
imported from the Argentine. Poplar Institute, and the Institute for Conifers are
establishing comparative plantings for the study of the hybrid material and the
irradiated material. The Poplar Institute is laying out test plantings with progenies
of Leuce-Poplars with the aim. to determine the silvicultural values of "the individual
families, the genetic values of parents, and the mechanism of inheritance.
Established were already 11 of such tests with 24 hybrid families.


In the experimental plots of the Institute for Dendrology and Genetics of the
Forestry Faculty, Zagreb, are being tested 120 clones of various Willows, 42 clones
of Narrow-leaved Ash, 2 clones of Pedunculate Oak, 2 clones of Black Alder, and
5 clones of Common Elm. Studied is also the coniferous clonal material, i. e. Pinus
nigra, P. silvestris, P. leucodermis, Picea omorika, and Abies alba.


IV. GENERATIVE REPRODUCTION
The generative reproduction (controlled, spontaneous) is the basic task of a selectionist
when working on the improvement of forest trees. Through this work we
can obtain new, improved races of forest trees with the properties modelled by man
according to plan. Controlled crossing is carried out between individuals of the same
or different forest-tree species. Taking into consideration that in the forest-tre species
of this country there prevail especially high constitutional individual variability
and the fractionation of the initial form on a relatively small area in biotypes and
ecotypes, efforts were made to utilize the hybrid vigour and the crossing of individuals
of the same species.


1. Hybridization within species
By this method of crossing we try to combine the good characters of one parent
with the good qualities of the other parent partner of the same spec´es. The experiments
peri´omed will be useful to know the value of plus trees by testing their
progeny as well as to study the occurrence of the hybrid vigour in the progeny.
Investigations are in progress.


a) Hybridization within coniferous species. These works have
been started by the Institute for Conifers, Jastrebarsko, and the Institute for Dendrology
and Genetics of the Forestry Faculty, Zagreb, in 1954. A controlled crossing
was carried out in Larix decidua, Pinus nigra and P. silvestris.


The Forest Institute, Skopje, started in 1962. an intraspecific crossing in Pinus
peuce, P. silvestris var. hamata, and Abies alba (Fir of the Mt. Perister). In these
species were selected the forms on the basis of the colour of generative organs (female
and male flowers), and other morphological features. Various combinations
are laid out in the necessary number of replications. In relation to the colour of
the generative organs crossed were the following pairs: red (violet) x red (violet),
red (violet) x green (yellow), green (yellow) x red (violet), and green (yellow) x green
(yellow). The production of hybrid seed and planting stock is in progress. The seeds
were studied as to their size, weight, colour, dimensions of wings and their colotiration.


Carried out were initial experiments with self-fertilization in P. peuce and P.
silvestris var. hamata. The first trials have shown for these species to be markedly
self-sterile.