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ŠUMARSKI LIST 1-2/1966 str. 173     <-- 173 -->        PDF

The Institute for Dendrology and Genetics of the Forestry Faculty, Zagreb,
started in 1960 with irradiation of seed of Pinus silvestris, P. halepensis, P. excelsa,
Larix decidua Applied were the doses from 50 to 20,000 r. Studied was the effect
of different doses on the germination of the seed and en the rate of growth. Lower
doses gave better results in respect of germination and growth rates (10, 14, 16). In
order to obtain mutations and the occurrence of heterosis in intraspectific and interspecific
hybridization of coniferous species, and to surmount the incompatibility
barriers at the crossing of Pinus nigra x P. silvestris, irradiated were the generative
organs. Irradiated was also the pollen of Larix decidua, Pinus silvestris, P. nigra
and Picea omorika by means of which were pollinated non-irradiated female flowers
of the same species (intraspecific hybridization). Carried out was also on interspecific
crossing between Pinus nigra, P. silvestris and P. brutia by means of irradiated
pollen. The irradiation dosages were 50 to 10,000 r. From a combination of P.
nigra x P. silvestris were obtained plants with pollen irradiated with 200,800 and
1,200 r. Several clones of P. nigra and P. silvestris in the stage of gametogenesis
were also irradiated. Parallel with these irradiation experiments also cytological
investigations were made. Tests are in progress (16, 19, 22).


The Institute for Forestry and Timber Industry, Beograd, initiated investigations
on the effect of ionizing radiations on the seed of highly resinous stems of the
Austrian Pine. It was established that in certain cases the height and diameter increment
can be stimulated. The progeny of various trees react differently to the
same doses. Doses exceeding 3,000 r cause dwarfing (38, 39).


At the Forestry Faculty, Beograd, was studied the effect of ionizing radiation
on the progeny originated from the irradiated seeds of several Poplar species. The
highest increase of increment was noted in doses of 1,000 r. In doses exceedig 1,000


r. a general tendency of stagnation in growth of both the overground parts and the
root system was conspicuous (34). Studied was also the progeny from the seed of
Austrian Pine treated with P-32 and it was established that depression of the germinative
power increases with the quantity of absorbed activity of P-32 in the seed,
and that the morphological changes on one-year-old plants of treated series were
highy pronounced. The progeny originated from the irradiated seed of Beech and
other broadleaved species was also studied as to the effect of ionizing radiation.
Investigations are in progress.
The Institute for Forestry and Timber Industry, Ljubljana started with radiation
experiments in 1957. Treated were germinated and dormant seeds of Spruce,
Beech and Larch. In the experiment were included 18 various provenances and 15
progenies of differential phenotypes and forms. The doses applied were 500 to 2,000


r. Certain doses a stimulating effect on the increment, while in definite series an
action towards the expansion of variation amplitude was significant. On an average,
Larch manifested a higher sensitivity than Spruce, while the latter exhibited
a varying sensitivity with respect to the altitude of the provenance.
At the Forest Institute, Skopje, the seed of Pinus peuce, P. nigra, P. silvestris
var. hamata, and Abies alba was treated with irradiation doses of 100 to 5,000 r.
The first observations indicate that the weaker doses have a better effect on the
germination percent; further, that the lethal dose for Pines is 5,000 r and for Abies
alba 2,000 r. and that the progenies, of different trees react in a different manner
as to the germination percentage under the same doses. Investigations are in progress.


At the Institute for Dendrology and Genetics of the Forestry Faculty, Zagreb,
were made trials by irradiating the cuttings of Salix alba and S. viminalis. Aplied
were doses of 50 to 50,000 r. The lethal dose was 5,000 r. Further investigations are
in progress.


2. Application of colchicine
Experiments on the artificial induction of hereditary changes have been made
by treating seed and terminal buds with colchicine.


At the Institute for Dendrology and Genetics of the Forestry Faculty, Zagreb,
the seed of Pinus nigra and P. silvestris were treated with 0.1—0.2´Vo doses of colchicine
while the immersion lasted from 1 to 8 days. Produced plants are under


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