The effects ofmutation induction by ion beam irradiation on axillary buds in rose were investigated. Axillary buds
were irradiated with carbon and helium ion beams, and the solid mutants emerged after irradiation by repeated cutting
back. In helium ion irradiation, mutations were observed in plants derived from 9 buds among 56 irradiated buds in
Orange Rosamini and in plants derived from 10 buds among 61 irradiated buds in Red Minimo. In carbon ion,
mutations were observed in plants derived from 12 buds among 88 irradiated buds in Orange Rosamini. Mutations
were induced not only in higher doses but also in lower doses, with which physiological effect by irradiation was hardly
observed. Irradiation with both ion beams induced mutants in the number ofpetals, in flower size, in flower shape and
in flower color in each cultivar.