Cultured rice cells were cryopreserved in liquid nitrogen. Cells pre-cultured with 0.4M sucrose survived cryopreservation by vitrification method. But the rate of survived cells was very low. On the other hand, the higher survival rate was obtained when the cells were cryopreserved by the pre-freezing method. It was important to culture cryopreserved cells on the ammonium ion-free medium for the higher survival rate. The viability of cryopreserved cells that were cultured on ammonium ion-free medium for only initial 8 hours was the same level to that of the cells cultured on ammonium ion-free medium for all the period. This result suggest that freezing injury of rice cells can be recovered rapidly during the initial stage of post-thaw culture when cultured with the condition of ammonium ion-free.
