effect of plant growth regulators on regeneration potential of axenic nodal segments of dendrobium chrysanthum wall. ex lindl.

dendrobium chrysanthum (orchidaceae) is highly valued in the ornamental industry and has important medicinal properties used in the preparation of herbal medicines in different parts of the world. however, this orchid species is getting depleted from its natural habitats due to unsystematic collections. therefore, in the present study, an efficient mass propagation protocol through direct shoot bud formation from axenic nodal segments of d. chrysanthum has been developed. the synergistic action between thidiazuron (tdz) and 6-benzyl amino purine (bap) was applied to enhance proliferation and elongation of shoots from the nodal segments. the explants were inoculated in ms medium fortified with different plant growth regulators viz., 2, 4-dichlorophenoxy acetic acid (2, 4-d), bap, and tdz, separately and in combinations. the maximum frequency of explants forming buds (100%), highest number of shoots/explant (14.33±0.14), the bud forming capacity (bfc) index of 14.33, and the maximum length of shoots (1.97±0.04) were obtained in ms medium supplemented with 5 µm each of tdz and bap. hundred percent rooting of regenerated shoots with an average number of 11.26 roots/shoot and having average root length of around 2.45 cm was obtained in ms medium fortified with 10 µm a-naphthaleneacetic acid (naa). sixty days after transfer to the greenhouse following in vitro acclimatization for 30 days, 79% survival was recorded. the protocol developed will not only help to alleviate the pressure on the natural population under stress, but will also help in meeting its demands in pharmaceutical and ornamental industries, and also form the basis for conservation.