| Oxygen and storage effects on radiation damage in einkorn
wheat seed T. MABUCHI and S. MATSUMURA National Institute of Genetics, Misima, Japan Dry seeds of Triticum monococcum flavenscens containing 13 % water were sealed in ampules filled with oxygen, nitrogen and air, and exposed to 10 and 15 kr gamma-rays. For acute and chronic irradiation dose rates of 10,000 r/hr with 137Cs and 19.7 r/hr with 60Co were used, respectively. Two chronic irradiations (10 and 15 kr) were terminated simultaneously before sowing. Acute irradiations were given at the time coinciding with the beginning and termination of the chronic ones. The inhibition of seedling growth was investigated. In general, chronic irradiations were found to be more effective than acute ones, especially at higher irradiation with 15 kr. There were no clear differences between air and oxygen treatment either in acute or chronic irradiation. On the other hand, nitrogen treatments clearly showed a protective effect on the inhibition of seedling growth, especially in acute irradiations. Unexpectedly, post-irradiation storage had no effect on the inhibition, also in acute irradiations. These results might be explained by the relationship between the production and decay of free radicals and radiation damage. It is assumed that nitrogen treatment decreases the radical yield, and the production and decay of the radicals are more gradual and slower in chronic than in acute irradiation. |