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.

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The work was conducted on the low energy electron irradiation of Citrus Unshiu fruits to prevent the growth of fungi and the deterioration. The present study was undertaken to investigate the influence of electron irradiation on the storage life of Citrus Unshiu fruits which were wrapped with some kinds of plastic films. Plastic film was used to prevent the electron irradiated fruits from infecting with micro-organisms in the storage period.
The permeabilities of water vapour and gases of plastic films were tested, and the five kinds of films, 1, 2-polybutadiene (PBD), polyethylene (PE), polyvinyl chloride (PVC), cellulose di-acetate (CA) and Vinylon (polyvinyl alcohol, PVA) were used for the experiment (Table 1).
The Citrus Unshiu fruits used were Sugiyama variety of medium class in fruit size, and harvested on 4th, Dec., 1971 at Harukigawa Izumi, Osaka. The fruits were stored for 20 days at 4°C, R.H. 80-90%, and the each of fruits was wrapped with plastic film and irradiated on next day with doses of 100 or 150 Krad. Fruits were irradiated from both of the stem-end and another end at each dose respectively by a Cockcroft-Walton type accelerator at 0.5 MeV and 450μA. After irradiation, the samples were stored at above mentioned condition. The items of growth of fungi, rotting, loss of weight, softening and browning of peel, destruction of oil-gland, and blackening of sepal were examined at every month after irradiation.
The results of growth of fungi and rotting of irradiated fruits are shown in Table 2. The wrapped ones with PE, PVC and PBD films which had low permeability towater vapour was lower in loss of weight, and stored in the good state for 2 months after irradiation, but at the 3 months, the percent of rotted fruits increased unexpectedly, and at the 4 months, all of fruits rotted. It was considered that the wrapping with PE, PVC and PBD films was not suitable for the long storage life of irradiated fruits. On the other hand, the effect of storage life of the wrapped ones with CA film which had higher permeability to water vapour was similar to non-wrapped ones. The percent of rotting, softening and loss of weight was smaller than those of non-irradiated (Table 2, 3 and 4). But, the percent of browning of peel, and blackening of sepal was higher than those of non-irradiated (Table 5). The loss of weight of the wrapped one with PVA was larger than that of non-wrapped (Table 3 and 6).
From these results, it was appeared that the tested plastic films, except CA, was not suitable for the preservation of Citrus Unshiu fruits. (Table 6).
Table 7 shows the results of pH, contents of sugar, citric acid and reductive Vitamin C for non- and irradiated, and non- and wrapped with PBD film.

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For the purpose of obtaining the knowledge of industrial grain irradiator design, the pilot plant of the new flow rate control type irradiator was made. This report presents the result of a study of the grain flow and the dose distribution in the irradiator.
Structure of irradiator
In this irradiator, grains are irradiated as they pass through annular cylinders and radiation source is located in the center tube. Grains are fed into each annulus by means of vacuum transfer system and reach to the bottom by gravity and pass through the slits of the annulus gate valves. The valves are used to control the flow rate and the dose is dependent on the flow rate in each annulus. The flow rate is controlled by the variation of shutting time of the valves and slit width. (See Fig. 1)
Experimental results
Fluidity:
1. Relative errors of vertical and horizontal components of flow velocity in each Irradiation Field were less than 1.9% and 2.9%, respectively.
2. The flow rate from the valve slits was independent on the curvature of the annular cylinders.
3. The flow rate was directly proportional to the slitwidth. (See (1))
4. There was a turbulence along the flow lane in the flow rate controller and the maximum staying time of rice in this turbulent region equals the time required rices travel a distance of about 20 cm in Irradiation Field. (See Fig. 2)
Dose distribution:
Relative errors of dose distribution in the irradiated rices were less than ±6.0%. (See Table 1)
The values of dose rate in Irradiation Field calculated by the introduced approximate formula agreed well with the data measured by cavity chamber.
(See Fig. 3)
Main merits of this irradiator
1. It is easy to irradiate large size of granules and to vary dosage.
2. The mechanical damage and the blocking troubles of grains at the slits are very little.
3. The dose uniformity in the irradiated grains is quite satisfactory, since the flow rate distribution is uniform in each Irradiation Field.

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