From approximately 100,000 rice plants of the first generation for which seeds were obtained from gamma irradiation, approximately 500 individuals that seemed to be prospective mutants, such as plants with short stems and early rice, were selected in 1999.
そこから採種された約10万本の第一世代の中から短稈化や早生化など、有益な突然変異と思われる約500個体を1999年に選抜。