In this paper we report the research on the effect of the different light in vitro conditions on growth and development of interspecific hybrid Cattleya intermedia × C. aurantiaca (Orchidaceae) maintained as stock in vitro shoot culture. Callus was obtained from shoots explants on initiation medium which was composed of MS mineral salts and vitamin set, supplemented with 30 g l^-1 sucrose, 2.0 mg dm^-3 adenine sulphate, 9.7 mg dm^-3 ascorbic acid, with addition of 1.0 µM TDZ, whereas callus maintenance medium was instead supplemented with 4.95 µM BA, and 1 µM NAA. Proliferating protocorm-like bodies (PLBs) of that precious plant material were exposed to the irradiation with monochromatic light characterized by different wavelength. Some interesting lines have been obtained on white, blue, red, far red, and ultraviolet light respectively, which proved to be diversified in the proliferation rates as well as in the morphological and anatomical features. The light treatment also significantly affected regenerative potential of studied culture. Blue light applied during two subsequent culture passages was proved to be the best option in order to regenerate shoots via PLBs. Nevertheless blue, red and far red irradiation of cultures led to distinctive reduction in the content of chlorophyll and carotenoid pigments, compared with culture irradiated with either white or ultraviolet light.

29-38