EFFECTS OF MEDIA STRENGTH AND MANNITOL CONCENTRATIONS ON GROWTH AND DEVELOPMENT OF Vandopsis lissochiloides PLANTLETS

Slow growth strategies are an alternative to in vitro methods and have become an important tool for medium-term storage of orchid germplasm. Protocols were developed for in vitro slow growth storage and acclimatization of Vandopsis lissochiloides plantlets to ex vitro conditions. Plantlets of
V. lissochiloides were cultured on full, half and quarter strength semi-solid Vacin and Went (VW) media supplemented with mannitol at 0, 2, 4, 6 and 8% (w/v), 30 g/L sucrose, 50 g/L potato extract and 150 mL/L coconut water for 24 weeks. At the end of the storage period, highest survival rate and growth performance in terms of leaf and root number were observed after transfer to the recovery medium in plantlets cultured on quarter strength VW medium without addition of mannitol.
These plantlets were successfully acclimatized and survived under ex vitro conditions at 90-100%. Highest percentages of new leaf and root formation were obtained in small size plantlets at 52% and 60%, respectively. Results showed that optimal storage medium for preservation of
V. lissochiloides plantlets was quarter strength VW medium without addition of mannitol, which maintained the viability of plantlets for up to 24 weeks without subculture.