Abstract
Gammer ray irradiation with the dose of 20-50 Krad on wheat and 10-30 Krad on rice were applied to control insect infestation during the storage of seeds.
In order to demonstrate the wholesomeness and safety of the irradiated wheat and rice seeds for human consumption, methods are needed which can detect whether these samples have been normally irradiated or not.
In the present work, the irradiated wheat (Norin-No.61 and Manitoba; 20, 50, and 200 Krad.), rice (Nihonbare and Koshihikari; 10, 20, and 30 Krad.), and their non-irradiated samples were investigated on the germination rate, the length of root and shoot, and the chromosomal aberration in root tip cells of germinating seeds.
The effects of irradiation on germination rate were observed on the third day after germination in irradiated and non-irradiated wheat and rice seeds. There were no significant differences between irradiated and non-irradiated samples on germination rate (Table 1 and 2.).
The results observed on the length of root and shoot for 5 days after germination are shown in Figs. 1, 2, 3, and 4. On the length of root and shoot, some differences were observed between irradiated and non-irradiated samples.
On the other hand, the numbers and percentages of abnormal cells in anaphage stage at the second day after germination and irradiation doses are presented Tables 3 and 4. In the non-irradiated samples, the root tip cells in anaphase stage were hardly observea on the cnromosomal bridges, whereas most of the cells in irradiated wheat and rice seeds had some bridges and micronucleas.
Figure 5 shows the abnormal anaphase cells from root tip of irradiated wheat seeds (Norin-No.61). A high incidence of chromosomal bridges in anaphase stage cells indicates that the wheat or rice seeds have been irradiated with lower doses, such as 20 or 10 Krad.
From these experimental results, γ-ray irradiated wheat and rice seeds can be identified by estimation of chromosomal bridges in anaphase stage cells from root tip of germinating seeds.
