Radioprotective effects of ascorbic acid in barley seeds

Abstract

Experiments were conducted to test the radioprotective effects of a naturally occurring reducing agent, ascorbic acid, on seeds (caryopses) of barley, Hordeum vulgare L. emend Lam. Seeds were soaked either before or after gamma or fission neutron irradiation in distilled water or ascorbic acid solutions ranging in concentration from 0·01 to 1·00 m. Results are reported as percentage germination, seedling height, seedling growth reduction, and (in one experiment) per cent of cells with chromosome aberrations.

As evidenced by both reduced germination and seedling growth, ascorbic acid was toxic when seeds were soaked for 1 hr at ambient temperature prior to irradiation and then planted immediately. When seeds were soaked in ascorbic acid before irradiation and soaked after irradiation in air-bubbled water at 0 °C for 18 hr, the toxicity disappeared, and a protective effect (which increased with increasing ascorbic acid concentration) was observed for gamma and, to a lesser extent, for neutron irradiation. Additional studies suggested that the protective effect was related to reduced hydration of the embryos of seeds soaked in ascorbic 'acid. Also, no radioprotective effect was observed when seeds were presoaked for 2 or 16 hr in 0·01 Mascorbic acid solutions buffered at pH 3 or pH 7.

A protective effect was observed for seeds of 1·5 per cent water content soaked after irradiation in an oxygen-bubbled ascorbic acid solution of 0·5 M but was not observed for seeds soaked in nitrogen-bubbled ascorbic acid. The protective effect against oxygen-dependent damage may be a result of interaction of ascorbic acid with radiation-induced free radicals.