In vitro germination of seeds of some rare tropical orchids

The objective of the study was to develop an appropriate method for in vitro seed propagation of Cattleya aclandiae Lindl., Cattleya bowringiana Veitch, Cattleya granulosa Lindl., Cattleya percivaliana O'Brien, Cattleyopsis lindenii (Lindl.) Cogn., and Dendrobium parishii Rchb.f. species, members of the Epidendroideae subfamily of the Orchidaceae family. Special attention was paid to studying the morphology of seeds, different stages of protocorms, and seedlings produced in vitro. Two seed types were been recognized according to the classifi cation of Dressler. The highest percent of seed germination (about 100 %) was obtained on the standard Knudson medium supplemented by 2 g l-1 peptone, 50 mg l-1 potassium hummate and 1 g l-1 activated charcoal. It was shown that Dendrobium parishii had the shortest (about 300 days) period of in vitro cultivation, and Cattleyopsis lindenii had the longest (about 600 days). The formation of Cattleya seedlings, on average, took about 500 days. By this time, the most advanced seedlings had been transferred to glasshouse. The use of immature seeds capsules as a seed source shortened the reproductive cycle by approximately 2 to 2.5 months. The results of these experiments showed that all of the studied species can be effectively propagated by in vitro seed culture with the aim of ex situ biodiversity conservation.