The use of Terminalia catappa L. (Combretaceae) seeds as a substrate for growing orchids of the species Oncidium flexuosum Sims, Dendrobium nobile Lindl. and Brassavola tuberculata Hook was compared to the tree fern fiber Dicksonia sellowiana Hook, largely used for that purpose. This species is endangered and its exploitation is prohibited by law. After twelve months, the following parameters were evaluated: aerial part height, pseudo bulb diameter, number of pseudo bulbs and pH of substrate. There was no significant interaction between substrates and species for the evaluated parameters. The orchids developed on T. catappa substrate and tree fern fiber showed similar aerial parts, diameter and number of pseudo bulbs. T. catappa substrate showed a low rate of decomposition, which maintained good aeration capacity, root development and pH values close to that found on tree fern fiber. T. catappa used as a substrate is viable as a substitute for tree fern fiber in the cultivation of these orchid species.
orchids; substrate; Oncidium flexuosum; Dendrobium nobile; Brassavola tuberculata