| Stems with axillary buds of cassava in three varieties- " Luyute" , "GR911"and "Fuxuan 01" were selected for in vitro culture. Four stages of primary research were processed, that is, establishment of clone system, multiplication of shoot, rooting and transplantation. The results are shown as below:1, Stage of establishment of clone systemThe stems of three varieties were selected to culture in winter, spring and summer, to compare their contamination rate, sprouting rate and growth condition of buds. It was best for cassava to culture in spring. The effect of sterilization was perfect when the explants were immature stems. MS medium supplemented with 1.0-1.5 mg/L BA were fit to induce sprouting. 2,Stage of multiplication of shootMS medium supplemented with 0.5-2.5mg/L BA could induce multiple shoots in three varieties. MS medium supplemented with 2.0mg/L BA was fit for "Luyute", while 1.5mg/LBA was fit for "GR911"and"Fuxuan 01". "Fuxuan 01" showed some properties different from the other two varieties. When subcultured in MS medium supplemented with 1.5-2.0mg/L BA and 0.05 mg/L NAA, shoot could be regenerated from warty-like callus that formed on the bottom of multiple shoots. So the combination of BA and NAA would play a better role in inducing shoots from callus than BA alone. 3,Stage of rootingThe rooting effect which induced by NAA was superior to that of IBA inthree varieties. When rooting induced by paclobutrazol, shoots were short and strong, leaves were greener and roots were thick., thus promoted the survival rate of transplantation. For all the three varieties, the modified 1/2 MS medium supplemented with 0.2-0.5 mg/L paclobutrazo or modified 1/2 MS medium supplemented with 0.1 mg/L NAA were suitable for rooting.4,Stage of transplantationTemperature and moisture affect the survival rate of transplantation. Low temperatuer and high degree of moisture would lead to the death of plantlet. The survival rate of transplantation in three varieties were 70% in March.
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