Abstract: An in vitro flowering system of Dendrobium candidurn Wall. ex Lindl., a wild species of orchid, was established. Callus was induced from seeds and protocorms formed on MS agar medium supplemented with 0.3 mg/L NAA under diffused light. Floral buds were induced when protocorms were cultured on MS agar medium supplemented with 2 mg/L 6-BA and 0.5 mg/L NAA, the frequency of floral bud induction being 27.0%. When protocorms were precultured on MS medium supplemented with 0. 5 mg/L ABA for 15 days and then transfered onto MS medium supplemented with 2 mg/L 6-BA, the frequency of floral bud induction increased greatly reach 84.0 % during a period of 5 months. Meanwhile the number of branches and floral buds also increased and in some instances inflorescence appeared. Never the less, no floral bud was formed if protocorms continued to be cultured on the ABA-containing MS medium.

Key words: Dendrobium candidum, ABA, In vitro flowering