. In order to stimulate efficient m

. In order to stimulate efficient micropropagation of PLB, much effort has been directed to modify the culture media, mainly by the inclusion of plant growth regulators [16,17] such as N6-benzylaminopurine and a-naphthaleneacetic acid [18], benzyladenine, gibberellic acid and 3indoleacetic acid [19], various polyamines [20], N6-benzyladenine and thidiazuron [21,22].
Plant tissue culture is particular suitable to study the effect of chitosan on plants that grow and multiply slowly, like orchids. In the work presented here, the formation of protocorm-like bodies in meristem buds and the growth and differentiation of orchid protocorm have been studied under the controlled conditions of tissue culture in the absence and presence of chitosan. Various chitosan preparations, both of crustacean and fungal origin have been compared in various concentrations.