1989 Volume 30 Issue 2 Pages 152-159_1
Identification of γ-irradiated grapefruit was investigated by observation of rooting and shooting of the grapefruit seeds. In order to reduce the incubation time for germination, indole-3-acetic acid (10ppm) and gibberellic acid (100ppm) were used to promote the rooting and the shooting, respectively. When incubated with the above plant hormones, a non-irradiated group started rooting in about a week after the incubation, and the root elongated with time, while an irradiated group (50krad) was slow in rooting and showed no emergence of roots with a length of 10mm or more. In 12 days, the emergence rates of roots with a length of 10mm or more in non-irradiated and irradiated groups were 30% and 0%, respectively. In 16 days, the emergence rates of the plumule in non-irradiated and irradiated groups were 20% and 0%, respectively. Thus, two features were critical for identification of γ-irradiated grapefruit: no emergence of a root with a length of 10mm or more, and no emergence of a plumule. This was also useful at low irradiation level, since the same phenomena were found in a grapefruit irradiated with 30krad. On the other hand, TTC activity in grapefruit seeds, used as a test of germination ability in cereal seeds, was not affected by γ-irradiation.
