Asymbiotic seed germination and in vitro seedling development of Paphiopedilum spicerianum: An orchid with an extremely small population in China

Paphiopedilum spicerianum is listed as one of the country's Wild Plants with Extremely Small Populations (PSESP). Procedures were developed for asymbiotic seed germination and seedling development aimed at producing seedlings for reintroduction. The highest germination was achieved in RECW with a 24 h dark cycle after pretreatment with 1% NaOCl for 40 min after 30 days from germination. However, these protocorms remained white and did not develop further. Although germination was lower under the same conditions in MSCW, it resulted in healthier and greener protocorms. Of four suitable media tested to promote seedling formation, Hyponex No 1 medium with 1.0mgl^-1α-naphthalene acetic acid, 0.5gl^-1 activated charcoal and 10% banana homogenate was the most effective. Advanced seedling development was seen in all six tested media during a 4 month growing period, with the highest leaf growth rate seen in the same media used for seedling formation, supplemented with 1.0mgl^-16-benzyladenine added to promote leaf growth. Fluorescein diacetate (FDA) tests on seeds showed that higher salt concentrations in the medium and longer duration of exposure to NaOCl reduce germination because of damaging effects on the testa and the embryo cells.