Chemical modification of postirradiation damage under varying oxygen concentrations in barley seeds

The influence of ascorbic acid, potassium permanganate and caffeine on postirradiation seedling injury of dry barley seeds was studied, irradiated (350 Gy 60Co γ-rays) in vacuo and post-hydrated with varying oxygen concentrations in the soaking medium. A linear response between the seedling injury and O2 concentration in the range of 0-80% was observed. Ascorbic acid did not exert any effect on seeds post-hydrated at OCHG (oxygen concentration in the post-hydration medium) of ≤ 30%, but afforded radio-protection at OCHG of ≥ 50%. Caffeine potentiated the postirradiation injury at OCHG of ≤ 30%, exerted no influence at OCHG of ∼ 50% and afforded radioprotection at OCHG of ≥ 80%. Potassium permanganate enhanced the injury OCHG of ≤ 10%, exerted no effect at OCHG of ∼ 30% and afforded radioprotection at OCHG of ≥ 50%. The possible radiation-chemical events in the dry irradiated seeds following their post-hydration containing different OCHG and the three test chemicals which are known free radicals scavengers are discussed. (author)