In Vitro Propagation of Endangered Orchid Taxa Using Alginate-Encapsulated Protocorm Like Bodies (PLBs)

In the present investigation various concentrations of sodium alginate and calcium chloride solutions were tested in order to optimize the size, shape and texture of alginate synthetic seeds or beads for Rhynchostylis retusa, an epiphytic medicinal orchid. The seven weeks old protocorm like bodies (PLBs) were encapsulated with 2 to 3% sodium alginate (w/v) in the BM medium and exposed to 50 to 100 mM calcium chloride solution (CaCl₂·2H₂O). It was observed that 3% sodium alginate dipped in 100mM CaCl₂·2H₂O solution was incubated for 40 min in orbital shaker to produce firm, transparent and uniform beads. The synthetic seeds were stored at 4°C and 25°C for 6 months to study their viability on the plantlets regeneration ability. The germination percentage of encapsulated PLBs decreased gradually with increase in storage time. This technology can be adopted for ex-situ germplasm conservation of medically important endangered orchids.