1. Three sepcies of roses, Gruss an Berlin, Super Star and John Strong were irradiated with 2,4,6 and 8 Kr and then the growth of the cuttings’ callues, stems, roots and leaves and their flowering were investigated. Results showed that all thses organs were apparently inhibited when the itradiation was done with more than 6Kr.2 . Half a year after irradiation (optimum dose 4Kr), mutations in flower colours have been observed in plants irradiated in thier seedling (grown out of cuttings of Gruss an Berlin and John Strong) stage.3 . When the dose was 4Kr, irradiated seedlings would produce more flower colour mutations than plants grown out of irradiated cuttings.