Keywords: Asymbiotic seed germination, Epiphytic, Grey orchid, Shoot proliferation, Vanda tessellata
Vanda tessellata (Roxb.) Hook. ex G. Don. (Orchidaceae) is an epiphytic orchid species, commonly known as grey orchid, and explored enormously for its significant horticultural, medicinal, phytochemical and pharmacological properties. The present study describes an in vitro culture approach via asymbiotic seed germination assisted by phytohormones and enhanced proliferation of shoots and roots using activated charcoal for large scale production of V. tessellata. The maximum frequency of seed germination (100%) was achieved on Murashige and Skoog’s (MS) medium fortified with 1.5 mg L−1 indole-3 butyric acid (IBA). The seedlings developed from the protocorms were used for further proliferation and development of multiple shoots (24.8 ± 0.52 shoots per protocorm with 5.2 ± 0.35 cm average length) on MS medium augmented with 0.5 mg L−1 each of 6-benzylaminopurine (BAP) and indole-3 acetic acid (IAA) + 100 mg L−1 activated charcoal (AC) after 4th sub-culture. The optimal rooting of individual shoots was achieved on MS medium with 1.0 mg L−1 IBA. The well-developed plantlets were hardened using soilrite® + cocopeat + coconut husk complex in a greenhouse for 4 weeks. The plantlets were acclimatized under relatively increased temperature and low humidity for 4–5 weeks in the greenhouse with 98% survival rate. The protocol can be utilized for the development of strategies for large scale stable production of V. tessellata plantlets.
The authors are grateful to the Science and Engineering Research Board, Department of Science and Technology, New Delhi, Government of India, for providing financial support as Extra Mural Research Project (EMR/2016/007795, dated 23-08-2017) to their laboratory.