Abstract:Traditional Cross breeding of Osmanthus fragrans is very difficult due to small size of flowers, styles, and very few of pollens. To investigate the effects of irradiation on Osmanthus fragrans seeds, seven varieties of Osmanthus fragrans were irradiated with different radiation doses of 60Co-γ, and the effects of radiation on seed germination and seedling growth were observed. The results indicated that the effects of radiation on seed germination varied among different varieties. Except for Zi Yingui, seed germination rate of the other six varieties was negatively correlated with radiation doses, the rate of germination and seedling were decreased with the increase of doses. Semi-lethal dose of six varieties of Osmanthus fragrans was 267, 151, 146, 135, 98 and 55Gy for Huangchuang jingui, Zhigeng zi yingui, Duanbing Zi yingui, Mihua Zi yingui, Jinzhan bzhu and Kuanye zi yingui respectively. Lower dose (50Gy) of radiation increased the germination of Huangchuan Jingui, Duanbing Zi Yin and Jinzhan bizhu. With high dose (200Gy),the rate of germination and seedling were inhibited greatly, especially with 250Gy, all materials except Zi yingui, the others cannot germinate. The results will provide a theory basis for mutation breeding and accelerate the breeding process of Osmanthus fragrans.