some explants even directly formed somatic embryos as time elapsed (Figure 1a). Although
the survival rate of explants decreased as the radiation treatment increased, survival was high
(approximately 90%) in the group exposed to 67 Gy radiation (Figure 2). The rate of somatic
embryo induction was approximately 75% for the groups derived from seeds exposed to 0 and
67 Gy; this rate also declined as the radiation treatment increased (Figure 2).
The explants that had formed somatic embryos were then transferred to the germination
and regeneration medium. After 2 weeks, some somatic embryo clusters developed, and some
somatic embryos grew into seedlings (Figure 1b). The regeneration rate was calculated after the
explants had been cultured on the medium with 4 mg/L 6-BAP for 8 weeks. The regeneration
rate declined as the radiation dose increased but was approximately 60% with 67 Gy (Figure 2).