| Chromosome aberrations in Einkorn wheat induced by
radiations Seiji MATSUMURA National Institute of Genetics, Misima, Japan When the relation between the frequency of chromosome aberrations in the PMC's of Triticum monococcum and the wave length of X-rays was studied, dotmant seeds were exposed to X-rays of different wave lengths (at 80, 130 and 180 KVP) , and different intensities (gamma/min) at the same dose (8,100gamma) without filter, as reported in the foregoing report. In the present experiment X-rays of different wave lengths were used at the same dose (8,100gamma) and intensity (95gamma/min), with different filters, and also gamma-radiations by Co60 were compared. The thickness of the filter was adjusted in inverse proportions to the wave length; that is, at 80 KVP no filter was inserted into Matsuda's Type KXC-17 apparatus, while at 130 KVP a filter 0.3Cu+0.5Al, and at 180 KVP one of 0.8Cu+1.5Al was used. At 50 KVP and 20 KVP, irradiation was applied by another apparatus, a modified Type KR-75 and Type TX-20 (Grenz-rays) without filter, respectively. The data are shown in Table 1. At 80-180 KVP, the results obtained in the foregoing report were confirmed, but at 50 KVP the aberration frequency was unexpectedly high. The question to be answered was, whether the dosages were measured correctly by Matsuda's dosemeter or "gamma"-meter. Therefore, measurements were again checked by Siemen's Universal Dosemeter. It became clear that the dosages at 80-180 KVP by Type KXC-17 decreased to 6,190-6,580gamma from 8,100gamma , while the dosage at 50 KVP increased to 8,350gamma. There were marked differences between the effects upon the germination rate and the aberration frequency at irradiation with X- and gamma-rays. The effects of gamma-rays were heavier than those of X-rays. At 16,200gamma of gamma-rays, all seedlings were uniformly small and died out about one month after germination, while in the case of X-rays the disturbances were small and variable. |