Asymbiotic seed germination,in vitro seedling development,and greenhouse acclimatization of the threatened terrestrial orchid Bletia purpurea

Procedures for asymbiotic seed germination and seedling acclimatization were developed for Bletia purpurea, a threatened North America native terrestrial orchid. Six asymbiotic orchid seed germination media (Knudson C, PhytoTechnology Orchid Seed Sowing Medium, Malmgren Modified Terrestrial Orchid Medium, Vacin &; Went Modified Orchid Medium, ½-strengh Murashige &; Skoog, and BM-1 Terrestrial Orchid Medium) were examined for their effectiveness in promoting seed germination and protocorm development of B. purpurea in either a 0/24 h or 16/8 h L/D photoperiod. Germination occurred regardless of medium or photoperiod treatment. However, advanced seedling development (Stage 6) only occurred on Vacin &; Went Modified Orchid Medium in the 16/8 h L/D photoperiod. Further effects of photoperiod on in vitro seedling development were also examined. Shoot length, leaf width, root number and length, and fresh weight and dry weight in the 16/8 h L/D photoperiod were all significantly different when compared to the 8/16 h and 12/12 L/D photoperiods. In vitro seedlings were readily acclimatized to greenhouse conditions. Seedlings showed high survival all potting media. Seedlings acclimatized in Fafard Mix 4 potting medium developed significantly longer roots. Corm formation occurred regardless of potting media used.