After 4 weeks on the induction medium, most explants that had been exposed to 0 or 67 Gy radiation had formed yellow-green somatic embryos or somatic embryo clusters, while a small number formed milk white calli. As the radiation level increased to 105 Gy, the number of brown explants increased. Although some explants in the 105 Gy group were able to form a callus, the callus gradually turned brown, and