Intergeneric hybrid of two rare and endangered orchids, Renanthera imschootiana Rolfe and Vanda coerulea Griff. ex L. (Orchidaceae): Synthesis and characterization

Renanthera imschootiana and Vanda coerulea are two rare and endangered orchid species featuring in IUCN Red List of Threatened Plants as well as in Red Data Book of Indian Plants, and are renowned for their unique ornamental traits. Renanthera imschootiana and V. coerulea have different flowering periods and by taking opportunity of off-season flowering of V. coerulea which happened during the flowering season of R. imschootiana, the hybridization was effected by hand-pollination. Viable pollinia were present in the off-season flowers of V. coerulea and one out of four cross was successful when R. imschootiana was taken as female parent. Reciprocal cross was unsuccessful. The resulting immature hybrid embryos were germinated in vitro on Vacin and Went medium supplemented with 15% v/v coconut water. Best seedling growth was observed on half-strength Murashige and Skoog medium devoid of any plant growth regulators while the transplanted seedlings grew best on brick chips:charcoal pieces (2:1) potting mix in community earthen trays. First flowering of the hybrid seedlings happened four years ten months after transfer to ex vitro environment. RAPD markers generated by the decamer primer OPA1 convincingly confirmed the hybridity. Registration of the hybrid was made with the Royal Horticultural Society with the grex Renantanda Kebisana Shija.