In vitro Asymbiotic Germination of Immature Seed and Formation of Protocorm by Cephalanthera falcata (Orchidaceae)

• Background and Aims Many Orchidaceous species are threatened globally by development and over-collection from their natural habitats for horticultural purposes. Artificial propagation from seeds is difficult in most terrestrial orchids native to temperate regions. Seed production is another limiting factor in the artificial propagation for these species because of the lessened probability of pollination and the destruction of fruit by insect larvae. Members of the genus Cephalanthera are distributed across Europe, Asia and North America. C. falcata is a temperate species of East Asia and an endangered species in Japan. As successful propagation from seeds of this species has never been reported, a reproducible method is described here for seed production in situ and propagation using immature seeds in asymbiotic culture in vitro

Constraints on establishment in an endangered terrestrial orchid: a comparative study of in vitro and in situ seed germinability and seedling development in Nervilia nipponica

Orchid seed capsules typically contain several thousand seeds, but obstacles to germination and development greatly constrain the establishment of new plants. This study compares the germination response of orchid seeds from the same capsule in situ and in vitro to assess the potential of soil conditions to influence recruitment. Mature capsules of the endangered Nervilia nipponica, a terrestrial orchid endemic to Japan, were harvested from two widely separated populations. On average, over 96% of seeds from all capsules contained an embryo. 2,3,5-Triphenyl tetrazolium chloride stainability was high and, when sown in vitro and cultured for 16 weeks asymbiotically, 76-99% of seeds from all but two capsules germinated and developed rapidly. However, when buried in seed packets for 7 months at the site of the source populations, germination was spatially variable and ranged from 0% to 12% per capsule. Embryo loss in buried seed was extensive, and germination was not significantly greater after a further 14 months of incubation. These results indicate that the window for successful germination under field conditions is short, and that recruitment is limited by microsite. Conservation efforts should focus on habitat management to promote conditions conducive to seed germination, coupled with ex situ propagation. (C) 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163, 166-180