Seed cryopreservation of orchid Coelogyne nitida (Wall. ex don) lindl. using air desiccation and vitrification techniques

Orchid seeds are short-lived and difficult to conserve using conventional methods. Diverse germplasm of orchids occurring in North-eastern parts of India need attention for their long-term conservation. In this study, seed cryopreservation in Coelogyne nitida (Wall. ex Don) Lindl. was attempted. A modified TTC test was standardised as a quick estimate of seed viability. In vitro asymbiotic seed germination was standardised for determining seed viability for fresh, desiccated and frozen seeds. MS medium supplemented with 0.6 mg l⁻¹ GA₃ + 0.8 mg l⁻¹ BAP was optimal. Cryopreservation by air-desiccation and vitrification methods were applied with success achieved in both, however vitrification method yielded much higher recovery (83.4%) after liquid nitrogen exposure than the air desiccation (43.5%). Exposure time to PVS2 of 40 min was optimal amongst the three treatment durations during vitrification. This is the first report on successful cryopreservation of Coelogyne nitida seeds.