Intergeneric hybridization of Aerides, Rhynchostylis and Vanda genera with stored pollinia of Thai orchids

Preservation of orchid pollinia is required for the intergeneric hybridization of species with different flowering times. Pollinia were collected from the flowers of three genera and fifteen species of male orchid plants. The pollinia were then refrigerated at 10 °C for a duration ranging from 4 d to 274 d, depending on the blooming period of Aerides, Rhynchostylis, and Vanda genera and eleven species of female parent plants. A total of thirty-six crosses of intergeneric hybridization were studied. Pod formation, the size and age of the hybrid pods, and in vitro seed germination were used to assess the capacity of the pollinia for fertilization. Results showed that pod formation (8.33% to 100%) was observed in twenty-seven crosses (75%), with the success of sixteen crosses of intergeneric hybridization (44%) having seeds with embryos that germinated into protocorms on modified VW (1949) medium or MS (1962) medium including, R. coelestis x A. falcata (48 d), V. liouvillei x A. houlletiana (4 d), V. liouvillei x A. multiflora (8 d), R. coelestis x A. multiflora (11 d), V. liouvillei x R. coelestis (18 d), A. rosea x R. coelestis (25 d), V. lilacina x R. gigantea “Alba” (47 d), V. lilacina x R. gigantea “Cartoon” (17 d), V. lilacina x R. gigantea “Red color” (23 d), A. multiflora x V. curvifolia (44 d), A. odoratum x V. curvifolia (44 d), R. coelestis x V. curvifolia (71 d), A. rosea x V. curvifolia (72 d), A. rosea x V. garayi (95 d), R. coelestis x V. garayi (95 d), and V. garayi x V. lilacina (53 d). All protocorms developed into plantlets after culturing on modified VW agar medium supplemented with 100 g L–1 banana, 150 mL L–1 coconut water, 20 g L–1 sucrose, 2 g L–1 activated charcoal, and 7 g L–1 agar. The intergeneric hybrid plantlets successfully survived in the greenhouse. Male pollinia can be stored at 10°C and utilized for the creation of orchid hybrids to progress orchid breeding and the preservation of Thai orchid species. The methods are uncomplicated and direct, needing no chemicals, tools, or complex procedures.