The asymbiotic seed germination of six Paphiopedilum species in relation to the time of seed collection and seed pretreatment

Paphippedilum, commonly known as the "lady's slipper orchid" is a fascinating genus of orchids. The wild populations are under the threat of extinction as a result of over-collection and habitat destruction, and species are listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The improvement of germination percentage could provide a practical way to re-establish plants in the wild and for commercial propagation. In this report, we study the effects of seed maturity and seed pretreatments on the asymbiotic germination of six Paphippedilum species (P. bellatulum, P. godefroyae, P. niveum, P. helenae, P. henryanum, and P. spicerianum). The timing of seed collection is critical in maximizing germination percentage in these six species. In P. bellatulum and P. niveum, the seeds collected from 120 to 150 days after pollination (DAP) were the optimum for culture in vitro. In P. godefroyae, the optimum time was found from 90 to 120 DAP. In P. niveum, the optimum time was found from 120 to 150 DAP. In P. henryanum and P. spicerianum, the optimum time was found from 120 to 180 DAP. Pretreatment of the mature seeds of six species with 1% NaOCI for 60 to 75 min improved the germination percentage. The pretreatment may scarify the seed coat and increase the permeability of seed, which improves germination of mature seeds.