The present study develops an efficient and reproducible protocol for the rapid in vitro mass propagation of the critically endangered epiphytic orchid Dendrobium terminale Par. & Rchb. Juvenile seedlings were produced from seed suspension culture. Dendrobium terminale is included in Appendix II of CITES (The Convention on International Trade in Endangered Species of Wild Fauna and Flora), showing its alarming position in natural habitat, ultimately emphasizing the need for its multiplication and conservation. Half MS media alone or supplemented with a combination of various concentrations of growth regulators: 6-Benzyl-aminopurine, BAP (2 and 4mg/L), 2iPA and Indole acetic acid, IAA (2mg/L and 4mg/L), were used, which produced callus, PLB, multiple shoots and leaves. The concentrations and combinations of auxin and cytokinin have a significant impact on plant growth, with certain combinations resulting in synergistic effects. It has been observed that BAP (4mg /L) and IAA (2 mg/L) were found to be most effective in promoting plant growth among the different combinations and concentrations of BAP, 2iPA, with IAA. The BAP (4 mg l-1) and IAA (2 mg l-1) recorded the highest number of PLB formation and significant leaf growth. The combination of IAA (2 mg l-1) and 2iPA (2 mg l-1) also promotes a higher percentage of PLB formation (75%) without necrosis. Whereas higher concentrations of cytokinin (e.g., 2iPA (4 mg l-1) tend to favour more callus formation.

Keywords:In vitro; Dendrobium terminale; Callus; PLB; IAA (indole acetic acid); BAP (benzyl aminopurine); 2iPA