Abstract:Cryopreservation conditions of normal buds of Cercidiphyllum japonicum were selected by different treatments combined with six protecting reagents,two vitrifying approaches and two low temperatures.The cells viability of the cryopreserved buds were investigated by TCC reduction test.The injuries of the cell ultrastructure of the cryopreserved buds were observed and analyzed by electron microscopy.The optimal cryopreservation technological conditions of the buds were confirmed by the experiments.The results showed that:(1)the protecting reagents,vitrifying methods and cryopreserving temperatures are all given significant impact on the cell viability of the buds.The different treatments of vitrifying cryopreservation formed different shapes and quantities of ice crystalloid within cells of the buds,resulted in the different amounts of the cell rupture.(2)The optimal cryopreservation condition of buds is that the buds can be marinated for 30 min in vacuum with the protecting reagents which consist of 35.0 mL glycerin,20.0 mL ethylene glycol,15.0 mL DMSO,1.0 mg glycine and 3% sugar deamination MS liquid in 100.0 mL volume,prefrozen for 6 h at -20℃,vitrified and cryopreserved in liquid nitrogen for 60 d,and lead to the highest cell relative viability of 95%.（3）the cell ultrastructure show that the elected optimal condition restrains obviously the formation of ice crystalloid inside cell and eliminates the swelling break of the cells effectively.The cell structures of cryopreserved buds are integrated and no injury.