MAJOR ACTIVITIES
ving
mse.
arch
ts of
sered
jeult
ttron
tion,
prest not
‘pons
57
in a different way. At certain dosage rates, some plants grow more
rapidly. The leaves of others grow in peculiar ways, and the coloring
of some flowers changes. Many mutations are produced andcareful
analyses are made both for fundamental causes and in searches for
useful new varieties. It is hoped that this research may supply positive answers concerning the usefulness of radiation as a tool in plant
breeding in the near future.
In addition to the cobalt source, the Brookhaven National Labora-
tory is making use of thermal neutronfacility for mutation production
in plants. It was shown that thermal neutrons are moreeffective in
producing mutations than other forms of radiation. Also, it is becoming clear from other studies that radiation damage to biological
material from neutrons is produced by quite a different mechanism.
from that which occurs following X-ray or gammairradiation.
Recent work with neutrons led to findings on inducing disease resistance in plants. Rust diseases bring annuallosses of millions of dollars to the oat crop—the Nation’s third largest cereal crop (after corn
and wheat). Investigators at Brookhaven exposed several hundred
oat seeds of the Mohawk variety to thermal neutrons. After the
first crops were harvested, seeds were planted in the summerof 1953
and a second-generation group grown. Artificial inoculations of oat
stem rust fungus (Race 7A), to which the Mohawkstrain is particu- _ ~
larly susceptible, were given to these plants. Seeds from the few un- -
infected plants were taken and planted in thefall.
Resultant plants
were inoculated with the rust disease but continued to showresistance
against it. As far as is known, the new strains haveall the desirable
‘adia. neucation
field”
characteristics of the original Mohawk variety, including high yield.
Further experiments to determine applicability to other varieties and
crops will continue.
les at
Radiation Effects on Tobacco and Potato Plants
Ticul-
radiation-of a species of tobacco plants. Results showed thatirradiation produced a moderately high rate of induced tumors. The tumorinduction rate at fairly High dosages (300 roentgens, r, per day) in the
gammafield was greatly increased over the control lot, not only in
iation
The
ns by =
mally ¢
| after
od are
e maations
ts the
ponds
Experiments in the Brookhaven “gamma field” ¥ also included
numbers of tumors per plant but in size of individual tumors. The
- significance of this response is not yet understood. However, it is
the first report of a tumorin plants induced by gammaradiation,although radiation-induced tumors have been recognized in animals for
many years.
4 See pp.75-80, 11th Semfannual Report.