prilagođeno pretraživanje po punom tekstu

ŠUMARSKI LIST 7-8/1960 str. 54     <-- 54 -->        PDF

9. Mülle r
I. H.: The Manner of Production of Mutations by Radiation; Radiation
Biology Vol. I. Part. I., 1954.
M ou t sehe n J.: Growth Modifications Due to X-Rays. Proceedings of the
Second United Nations International Conference on the Peaceful Uses of Atomic
Energy, Volume 27, Geneva, 1958.
Sari č R. M.: The Effect of Irradation on the Branching of corn (Maize) Stalks.
Proceedings of the Second United Nations International Conference on the
Peaceful Uses of Atomic Energy, Volume 27, Geneva, 1958.
12. Sari ć R. M.: The Dependence of Irradation Effects in Seed on the Biological
Properties of the Seed. Proceedings of the Second United Nations International
Conference on the Peaceful Uses of Atomic Energy.

Stapleton E. G. — Hollaender A.: Biochemical and Cellular Effects; Radiation
Biology and Medicine, Reading, Massachussetts, 1958.

Radiated with gamma rays were the seeds of Scots Pine, Austrian Pine and
Norway Spruce. The seed was radiated during 24 hours with a Co-60 — source of
0,9 C at the distances of 20, 30, 40, 50 and 60 cm, and doses of 82, 119, 187, 332 and 748
R-units. Other samples of the same seed were radiated with a Co-60 — source of
305 C, while the dosage was from 500 to 20.000 R-units as visible from Tab. 1. In this
case all samples were radiated under equal geometrical conditions. Germinability
for each dose was tested on 300 seeds while 600 seeds served as controls. The interval
for testing germination was 40 days. The percentage of moisture was not measured.
The radiated seed of Norway Spruce and Scots Pine was about 1 year old while the
seed of Austrian Pine was about 3 years old.

With doses from 82 to 2500 R-units the germination in Scots Pine was increased
up to 96,30°/o while in the controls it was 84,85´Vo. In the Austrian Pine the control
seed had a germination of 42,66|3/o. The increase of germination sets in at a dose of
748 R-units and goes on up to 3500 R-units. Within these dosing limits the highest
germination is at 3000 R-units and amounts to 49%. In the Norway Spruce the controls
displayed a germination of 84,83´%, while the increase of germination in treated
seeds sets in at a dose of 500 R-units, and keeps on (exceptig some deviations) up to
550 R-units. The maximum germination of 89,31´% was at a dosage of 4000 R-units.

The mean time of germination Y as visible from Tab. 1 increases in all the three
species with the increase of dosage (excepting some deviations).

The dispersion of a around the mean time of germination (Tab. I.) is in small
doses for all three species smaller than in their controls while in larger doses it is the
converse. Only in Austrian Pine — in doses larger than 13000 R-units — is the dispersion
of treated seeds smaller than that of the controls.

The Scots Pine possesses at a dose of 14000 R-units a germination of 0,67°/o, and
we can consider this dose to be already the treshold of lethality. Yet at the dose of
20000 R-units the Austrian Pine and Norway spruce display a germination of 12,33´%
and 28,67% respectively.

On the graphs is shown the number of germinated seed by days. The histograms
represent the germinating power for the first 7 and 14 days respectively.

In Norway Spruce the germination power for the first 7 days is higher at doses
of 187, 332 and 748 R-units, while in other doses it is lower than in the controls. In
Scots Pine the germinating power in the first 14 days in doses up to 2500 R-units is
higher than in the controls, while in larger doses it is lower. In Austrian Pine the
germinating power at small doses is approximately equal to that of controls. In a
dose of 748 R-units the germinating power is somewhat higher than that of the controls,
whereafter it decreases.

Consequently it can be concluded that by radiation with small doses the germinating
power of seeds of Norway Spruce, Scots Pine and Austrian Pine is increased.
Scots Pine displays in this case the greatest regularity.

The smallest increase of germinating power occurs in Austrian Pine, whose seed
was the oldest. It can be supposed that with the ageing of seeds the radiation with
small doses can only effect a very small increase in the germinating power.

The seed radiated with 5000 R-units (see Table and Graphs) shows a great deviation;
therefore data should be taken with grain of salt, while the experiment
should be repeated.