PREDICTION OF THE SENSITIVITY OF PLANTS TO CHRONIC GAMMA IRRADIATION
Vegetative growth and the integrity of the sexual reproductive process of pines appear to be highly susceptible to damage from ionizing radiation and the genus Pinus includes some of the most radiosensitive plants known. Chronic exposures averaging about 8 months per year for 9 years produced detectable effects on growth of P. rigida at average dose rates as low as 2 r/day. The lethal acute dose for P. strobus seedlings of 600 r also indicates a high radiosensitivity. The principal reasons for the high sensitivities are the large nuclear volume of pines and, for chronic exposures, the long period between production of the meiocytes and the maturation of seed. It is predicted that many other gymnosperms will have a radiosensitivity approaching that of pines. A comparison of the estimated maximum exposure of vegetation from fall-out occurring in New York City in 1958 with the minimum chronic radiation levels known to influence growth and reproduction of Pinus rigida indicates that these levels of fall-out are approximately 1/800th of the 2 r/day necessary to produce visible morphological effects within several years. A forest stand representative of the Long Island oak-pine forest is currently being irradiated with chronic gamma radiation from about 9500 c of cesium-137 in an effort to provide quantitative estimates of radiation effects at the population and community levels. Present information makes possible the prediction, on the basis of nuclear characteristics, that the first year's exposure will cause selective killing. All trees within 85 m of the source (85 r/day) will die leaving a shrub community dominated by Gaylussacia baccata, probably one of the most resistant of the species present. The pitch pine (Pinus rigida), with its large nuclear volume, is the most sensitive plant present and will probably be killed by the second year at distances up to 75 m (15 r/day). (auth)
- Research Organization:
- Brookhaven National Lab., Upton, N.Y.
- NSA Number:
- NSA-16-030247
- OSTI ID:
- 4784120
- Report Number(s):
- BNL-5932
- Journal Information:
- Radiation Botany, Vol. Vol: 2; Other Information: BNL-5932. Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- United States
- Language:
- English
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