IN-VITRO GERMINATION OF 3 CYPRIPEDIUM SPECIES IN RELATION TO TIME OF SEED COLLECTION, MEDIA, AND COLD TREATMENT

To maximize the in vitro seed germination of three Cypripedium species , C. candidum Muhl. ex Willd., C. reginae Walt., and C calceolus var. parviflorum Salisb. Fern., the optimum time of seed collection and the suitability of various media were studied. A cold treatment was inves tigated for C. candidum. Seed pods were collected at regular intervals after pollination, ranging from green pods at 5 weeks to dry undehisc ed pods at 12 weeks. Seed was inoculated onto three media, Harvais, Va n Waes and Debergh, and a modified Norstog and germination was assesse d at 4-week intervals for 20 weeks. Cypripedium reginae germinated bet ter than the other two species. Except for C. candidum in 1989 when ge rmination peaked for seed collected at 6 weeks after pollination, seed collected at 8 weeks after pollination had the highest germination. A fter 8 weeks, germination decreased sharply in all species, dropping b elow 1% for C candidum. There were differences among media but the eff ects on germination were not consistent and depended on the year, die date of collection, and the species. Subsequent development of protoco rms was superior in all cases on the modified Norstog medium. The effe ct of cold treatment on germination of C. candidum was variable and th erefore its importance is questionable.