Seed germination and tissue culture studies in orchids

Abstract

Investigations were carried out to standardize in vitro culture techniques and find out the effect of different culture media, growth substances, and other additive on seed germination and tissue culture of orchids. Studies on cytological and histochemical changes associated with orchid seed development were also made. Comparison of five different media (Knudson, C., Murashige-Skoog, Vacin and Went, Burgeff N3F and modified Vacin and Went) for germination and growth of seeds of six different orchid species showed that Vacin and Went medium was superior in respect of germination, growth and development of Bletilla hyacinthine, Phaius wallichii and Epidendrum radicans, while Murashige-Skoo medium was found superior for Spathoglottis plicata and Vanda coerulea. Burgeff N3F medium was found suitable for different Dendrobium species. Histochemical studies revealed that the seeds of Bletilla hyacinthine contained considerable amount of lipids and proteins but no starch. The developing protocorm exhibited a decreasing gradience in the size of its cells and its nuclei. Ribonucleic acid and proteins showed an increasing gradiance in the protocorm like body from its base to apex. The peripheral cells of the callus of Dendrobium pierardii contained rich cytoplasmic RNA and proteins and a few starch grains. Cytological evaluation of the cultured tissue revealed the presence of chromosomal variations in different cells. This may be due to the stress caused by the unnatural environment by cell fusion.