In Vitro Propagation of R. maddeni Hook. F. an Endangered Rhododendron Species of Sikkim Himalaya

A protocol is described for rapid and large scale propagation of an endangered, important Sikkim Himalayan rhododendron (R. maddeni Hook. f.) by in vitro culture of cotyledonary nodes from 15 days old seedlings. Several cytokinin types were evaluated for their effect on shoot multiplication from cotyledonary nodes. Maximum numbers of shoot (12.00 �0.58) were observed on the AM containing 7 mg/l 2iP, 0.1 mg/l IAA after eight weeks of culture. Incorporation of 0.1 mg/l IAA in the medium during the first subculture after establishment and initiation of shoot buds significantly improved the shoot elongation. Regenerated shoots were separated and rooted on same strength AM medium supplemented with 0.2 mg/l of IBA alone for three weeks. Well-developed complete plantlets were transferred on to specially made plastic cup containing soilrite. The rooted plantlets were hardened and successfully established in greenhouse, the plants were transferred to field site at Pangthang arboretum of the Institute and the �Rare & Threatened Plant Conservation Park� of Zoological Park, Gangtok, Sikkim.