X-ray induced mutations in Sweet Potato

Abstract

Young shoots of sweet potato plants were irradiated by X-rays to induce some new "sports" due to somatic mutations. As sweet potato plants are usually propagated by vegetative reproduction, that is, by planting young shoots from parent tubers, the X-radiation of young shoots was considered asthe effective treatment method to induce artificial mutations. We irradiated the young shoots sprouted from tubers of variety Norin No. 1, which produce tubers of brown red colour, at the dosage of X- rays ranged from 5000 r to 20000 r and 61 r/m in intensities at all cases. After treatments, shoots were cut to some short pieces having one leaf on each and planted in little pots of 10 cm diameter. Although some irradiated shoots died, almost ones were sprouted after fewweeks. Survival rate was decreased linearly according to the dosage and 30 per cent of shoots treated by 20000 r survived at maturity. Many varia. tions of leaves, stems and tubers or inhibitions of growth were recongnized in the treated generation and such variations in X₁ was seen as to increase with the treated dosage. Main variation was recorded on frequent appearance of chimera tubers with epidermis colour of brown red and yellow white.