Propagation and conservation of Podophyllum hexandrum Royle: an important medicinal herb

Podophyllum hexandrum Royle, a source of highly valued podophyllotoxin, has been subjected to heavy collection from the wilds due to ever increasing d emand. This report deals with the successful propagation of this species us ing both conventional and in vitro techniques. To improve vegetative multip lication, rhizome segments were treated with alpha-naphthaleneacetic acid ( NAA) or indole-3-butyric acid (IBA) before planting; more than doubling in rooting percentage was observed with 100.0 mu M IBA. Seed germination gener ally started 3 months after sowing, and pre-treatment with sodium hypochlor ite resulted in five-fold improvement, while 250.0 mu M gibberellic acid (G A(3)) and a combination of GA(3) and 6-benzyladenine (BA; 250.0 mu M each) enhanced germination by nearly two-fold; other treatments were either ineff ective or enhanced germination only marginally. Excised zygotic embryos ger minated within 7-8 days of culture on basal medium or on medium supplemente d with indole-3-acetic acid (IAA; 1.0-4.0 mu M) and BA (1.0 mu M). Multiple shoots were formed within 4-5 weeks; following rooting of these shoots, pl ants were transferred to hardening pots. Somatic embryos were formed from c allus derived from zygotic embryos after 4 months of culture on medium cont aining 5.0 mu M NAA and 0.5 mu M BA. Various strategies have been discussed to encourage cultivation of this medicinal herb so as to reduce pressure o n its population in the wild. (C) 1999 Elsevier Science Ltd. All rights res erved.