Sprout-inhibition of Sapporo-ki Onions and the Changes of Nucleic Acids in their inner Buds by Gamma Radiation

Abstract

The relationships between the delay of the time of gamma irradiation and the sproutinhibition of Sapporo-ki onions were studied, and the nucleic acid content in inner buds of the onions was also determined. The onions were irradiated with the doses of 3-15 Krad and stored at room temperature except for the constant temperature lots of 1°, 6°, and 20°C. Onions which were irradiated 2 weeks after harvest did not sprout completely. However, when irradiation time was delayed about 4 weeks after, the inhibitory effect of gamma radiation on the sprouting was remarkably reduced. In irradiated onions stored 3 weeks after harvest, their inner buds had elongated slightly, and it was similar to the state of inner buds of Senshu-ki onions in budding period. Moreover, a similarity between their inner buds was observed in the pattern of the chromatograms of nucleic acids separated by using MAK column. The contents of s-RNA, r-RNA and DNA of inner buds in irradiated onions decreased by about a half of that in unirradiated onions 2 months after irradiation, and there was no difference between the contents of nucleic acid in 5 Krad onions and in 15 Krad ones.