In vitro rapid propagation of an endangered medicinally important Orchid species via immature embryo culture

In the present study, the asymbiotic germination potential of immature seed (embryos) was assessed in economically and medicinally important orchid Dendrobium nobile species. Immature seeds from unripened green capsules (15 weeks after pollination; wap) germinated readily on KC medium. The ability to germinate even in basal medium (without plant growth regulators; PGRs), was interesting and suggests the simplicity of their nutrient requirements. Since the germination frequency and the morphogenetic changes leading to protocorm differentiation were markedly influenced by the chemical stimulus in vitro, stage specificity of nutrient requirements is indicated in the germinating entities. In basal medium, nearly 35% seeds responded to germination within 47.50 days after inoculation, while, in the treatments fortified with different plant growth regulators concentrations and combinations, germination response were significantly improved and 45.25-100.00% of inoculated seeds germinated in 28.25–38.25 days. Additional presence of PGRs in the medium enhanced the percent response besides promoting multiplication of germinating entities; cent per cent seeds germinated in NAA+KN(0.50+0.50mgl-1) and BAP+KN(25+0.50mgl-1) treatments. The early embryonal mass emerged out of the vertically ruptured seed coat as a spherule in 38.50 days in NAA+KN(0.50+0.50mgl-1) treatment which containing auxin and cytokinine equally. Protocorm obtained in NAA(1mgl-1) and NAA+BAP(0.50+0.50mgl-1) treatments were bright green, globular and actively proliferating with several hairoids along the base in 55.75 days of embryo culture. Their subsequent protocorm differentiation were achieved in KN+BAP (0.50+0.50mgl-1) within 70.25 days.