Axillary multiplication of <Emphasis Type="Italic">Swertia chirayita</Emphasis> (Roxb. Ex Fleming) H. Karst., a critically endangered medicinal herb of temperate Himalayas

The present study describes the micropropagation of Swertia chirayita, an endangered medicinal herb of the temperate Himalayas, through axillary multiplication from 4-wk-old seedling-derived nodal explants. We obtained 4.5-fold multiplication every 4 wk on Murashige and Skoog (MS) medium supplemented with 4 μM benzyl amino purine (BA) and 1.5 μM 6-(γ,γ-dimethylallylamino)purine (2iP). Rooting was optimized on modified MS medium supplemented with 1 μM naphthalene acetic acid (NAA) and 500 mg l⁻¹ of activated charcoal (AC). A success rate of 94 % was obtained by in vitro hardening in the growth-room and by ex vitro hardening in greenhouse conditions. The present study can serve as a tool for the mass multiplication of elite genotypes of this critically endangered species and can also be utilized for multiplying large numbers of quality planting material for the replantation in their natural habitat. This approach can also help meet the requirements of the growing pharmaceutical industry by ensuring the regular supply of authentic planting material.