Hardening of tissue-cultured plantlets of orchid (Rhynchostylis retusa) at different substrata

Three locally available low cost materials, viz. coir, luffa and polystyrine foam were chosen because of their easy availability for in vitro propagation of Rhynchostylis retusa Blume, an epiphytic herbaceous orchid commonly seen in the forests of Western Ghats. In vitro hardening was done on different substrata such as coir, luffa and polystyrene sponge instead of agar. Coir was the best rooting medium than sponge and luffa. After that the plants were transferred in plastic tray for ex vitro acclimatization in greenhouse.