Effectiveness of fission neutrons, 14.7-MeV monoenergetic neutrons, and $sup 60$Co gamma radiation on seedling growth reduction and induction of chlorophyll-deficient mutations in barley

Book · Mon Jan 01 04:00:00 EST 1973

OSTI ID:4348983

Conger, B V; Constantin, M J

Experiments with seeds (caryopses) of two barley cultivars ( Hordeum vulgare L. emend. Lam. cv. Himalaya and Atlas-57) are described. Growth of Himalaya seedlings from seeds of 2 to 13% water content irradiated in vacuo aad soaked in nitrogen-bubbled water at 0 deg C indicated fission neutrons N/sub F/ to be 54 to 60 times more effective than /sup 60/Co gamma radiation. When seeds were irradiated similarly, but soaked in oxygen-bubbled water at 0 deg C, the RBE of N/sub f/ ranged from 7.6 at 2.2% to 60 at 13.0% water content. At 32% water, seeds became more radiosensitive but proportionally more so to gamma radiation, therefore the RBE of N/sub f/ decreased to 7.5. Germinated seeds (24 hr.) were slightly more radiosensitive than dormat seeds of 32% water content and the RBE of N/sub f/ was 6.8. The chaage in RBE of N/sub f/ with changing seed water content and/or oxygen availability is caused by the greater effect of these factors on the modification of gamma -radioinduced damage. The results are discussed in terms of direct versus indirect mechanisms of radiation action. In seeds of 13% water, 14.7 MeV neutrons were slightiy less effective than N/sub f/ in reducing seedling growth of both Atlas-57 and Himalaya. Both neutrons were 50 to 60 times more effective than gamma radiation. The Atlas-57 cultivar was more sensitive to all three radiations than Himalaya. For the chlorophylldeficient mutation studies, seeds of Atlas-57 were adjusted to a water content of 13% and irradiated with varying doses of /sup 60/Co gamma radiation, N/sub f/, and 14.7 MeV neutrons. Mutagenic effectiveness of N/sub f/ was higher than 14.7 MeV neutrons but both neutrons were much more effective than gamma radiation. The RBE's for mutations per 1,000 M/sub 2/ seedlings per rad x 10/sub -2/ were 73.2 and 132.2 for 14.7 MeV neutrons and N/sub f/, respectively, compared to gamma radiation. Mutagenic effectiveness, calculated on an M/sub 2/ seedling basis was independent of dose for all radiations. Mutagenic efficiency computed on the basis of the frequency of mutations per 1,000 M/sub 2/ seedlings versus percentage reduction in M/sub 2/ seedlings per spike showed that /sup 60/ Co gamma rays may be more efficient than either of the two types of neutrons. (GE)

• Research Organization: UT--AEC Comparative Animal Research Lab., Oak Ridge, TN
• NSA Number: NSA-29-015914
• OSTI ID: 4348983
• Country of Publication: Germany
• Language: English

Related Subjects

*BARLEY-- MUTATIONS
*FAST NEUTRONS-- RBE
*FISSION NEUTRONS-- RBE
*MUTATIONS-- RADIOINDUCTION
*SEEDS-- RADIOSENSITIVITY
BIOLOGICAL RADIATION EFFECTS
CHLOROPHYLL
GAMMA RADIATION
MEV RANGE 10-100
N48410* --Life Sciences--Radiation Effects on Plants--Basic Studies
NEUTRON BEAMS
NITROGEN
OXYGEN
PHOTON BEAMS
PLANT GROWTH
RADIOSENSITIVITY EFFECTS
RESPONSE MODIFYING FACTORS
SEEDLINGS
WATER