INFLUENCE OF SOME PLANT-GROWTH REGULATORS ON THE GROWTH AND ORGANOGENESIS OF CYMBIDIUM-ALOIFOLIUM (L.) SW. SEED-DERIVED RHIZOMES IN-VITRO

An efficient procedure is outlined for in vitro regeneration of an epi phytic orchid, Cymbidium aloifolium (L.) Sw. using rhizomes developed from seeds. Murashige and Skoog's (1962) medium (MS) containing indole -3-acetic acid (IAA), indole-3-butyric acid (IBA), or 1-naphthaleneace tic acid (NAA) stimulated growth and proliferation of rhizomes with NA A being most effective at 5.0 mg.l(-1) (27.0 mu M). Shoot bud differen tiation was induced in the epical portions of the rhizomes on MS mediu m containing kinetin (Kn) or N-6-benzyladenine (BA). The highest frequ ency of shoot regeneration (91.5%) and the maximum number of shoot bud s formed (3.5 shoots/rhizome) were recorded with EX at 1.0 mg.l(-1) (4 .4 mu M). NAA (0.1 mg.l(-1), 0.54 mu M), whenever added to the medium in conjunction with BA (1.0 mg.l(-1), 4.4 mu M), slightly enhanced the frequency of shoot bud regeneration (92.6%) and the number of shoot b uds formed (5.2 shoots/rhizome). Moreover an NAA-BA combination induce d rooting in regenerated shoots thereby producing complete plantlets i n one step. Shoots developed on cytokinin-supplemented medium were roo ted on MS containing NAA at 1.0 mg.l(-1) (5.4 mu M). Regenerated plant lets were acclimated and eventually established in a garden.