Modification of the Radiosensitivity of Barley Seed by Post-treatment with Caffeine

Summary

The oxygen-dependent damage which develops in barley seeds with ∼7·8 per cent moisture content disappears after post-irradiation storage in vacuo for 48 hours at 40°C and for 24 hours at 50°C. When the duration of storage at 40°C is extended to 384 hours, oxygen-independent damage becomes potentiated. There is oxygen-dependent damage in seeds of ∼13·3 per cent moisture content and after the seeds have been stored in vacuo at 50°C, the oxygen-independent damage begins to increase by 168 hours, and it is very significantly potentiated by 192 hours.

Under these circumstances, caffeine acts as a radioprotector only as long as the precursors of oxic damage are present in the seeds. Once these sites are lost, caffeine acts only as a radiosensitizer. The oxygen-independent damage which increases with storage at high temperature is further potentiated by caffeine.