Effect of gamma irradiation on sprout inhibition and its physiological mechanism of Chestnuts

Abstract

From the results of this experiment on the effects of gamma irradiation on the sprout inhibition and its physiological mechanism purporting the extention of storage life of chestnuts, the following summary can be made.
Chestnuts harvested in October were irradiated with 1×10⁴, 5×10⁴ roentgen of Co 60 gamma rays, then stored in moist sawdust at room temperature. On February, over 50 percent of nuts which had been received in low doses roentgen showed visible growth of roots, but in the untreated nuts only 30 percent. After that, the roots of untreated nuts had continued vigorous growth, whereas the rooting of the treated nuts with the lower dose were gradually prevented, but not completely stunted. On the other hand, high doses completely inhibited the rooting and sprouting. Most of treated with the nuts with the higher doses were still salable in April. More rotting were found in the treated nuts higher doses than those with the lower doses. Such unfavorable effects tended to increase in the nuts with higher under the elongated storage. From these observations, concerning results with beneficial effect of root and sprout inhibition, it is supposed that the range of 3.5×10⁴ 5×10⁴ roentgen is the most desirable level of treatments.
Total ascorbic acid contents were slightly diminished in paralell with increasing dose levels and elongation of storage times. Sugar contens showed that the conversion of starch to sugars progressed slightly by the irradiation. Soluble astringent contents did not show any change by the irradiation.
The effects of irradiation on the respiratory activity were obviously recognized, but it seemed that the changes of respiration had not so much direct correlations with mechanism of root and sprout inhibition.
The amylase activities decreased immediately after irradiation but rapid and significant increasing followed just after. No important variations were found in either polyphenoloxidase or peroxidase, though showed a tendency to decrease with small inactivation by irradiation. The correlation between the rotting and the oxidase activity was not clear.