A Comparative Study of Vitrification and Encapsulation-Vitrification for Cryopreservation of Protocorms of Cymbidium eburneum L., A Threatened and Vulnerable Orchid of India

Cryopreservation of the threatened orchid Cymbidium eburneum L. was successfully achieved using encapsulation-vitrification and vitrification. Comparing the two methods tested, it was observed that regeneration of protocorms cryopreserved using encapsulation-vitrification was higher than with vitrification. To achieve optimal regrowth after cryopreservation, protocorms were precultured for 24 h with 0.2 M sucrose for vitrification and with 0.7 M sucrose for encapsulation-vitrification, reaching 60% and 70% regeneration, respectively. With both techniques employed, a 20 min exposure duration to Plant Vitrification Solution 2 (PVS2) led to optimal regeneration after cryopreservation. A maximum of 66% regeneration was achieved after cryopreservation using encapsulation-vitrification, whereas it was only 50% after cryopreservation using vitrification. The same regeneration pattern was observed with protocorms cryopreserved using both techniques employed. This is the first report of long-term conservation by cryopreservation of C. eburneum protocorms.