High frequency early flowering from in vitro seedlings of Dendrobium nobile

Dendrobium nobile Lindl. is a popular temperate Chinese orchid commonly marketed as a traditional medicinal plant. Seedlings of Dendrobium nobile Lindl. produced floral buds (33.3–34.8%) precociously on a defined basal medium (1/2 MS) containing paclobutrazol (PP333) at 0.5 mg L−1 or thidiazuron (TDZ) at 0.1 mg L−1 within 4 months of culturing. The frequency of floral buds formation can be further increased to 95.6% by growing seedlings in a PN (PP333 0.3 mg L−1 + NAA 0.5 mg L−1)-containing medium followed by transfer onto 1/2 MS medium with PP333 and TDZ (PP333 + TDZ). However, flower developed was deformed under 25 °C but it developed fully when grown in a lower temperature regime (23 °C/18 °C, light/dark) for 45 days. Under optimal condition, in vitro flowering was observed about 6 months after seed sowing.