Abstract: With the axillary buds of in vitro plantlets of Dioscorea alata L.from Taizhou City，Zhejiang Province，the effect of microtuber formation and development was studied based on different medium volumes，plant growth regulator concentration ratio，sucrose concentration and illumination intensity. The results showed that the preferred condition for induction of microtuber was 1/2MS basal medium supplemented with 0.1 mg · L^-1 6-BA，2.0 mg · L^-1 NAA，70 g · L^-1 sucrose and 0.02% activated carbon under 2 000 lx illumination intensity. The volume of 1/2MS was 60 mL for every tissue culture vessel which standard was ZP17-440. The microtuber began forming at the 40 d and the inductivity reached 100% in 90 d.

Key words: Dioscorea alata L., tissue culture, microtuber induction