EFFECT OF DIFFERENT SUBSTRATES ON GROWTH OF ORNAMENTALS IN HYDROCULTURE

The effect of four substrates (expanded clay, expanded polystyrene, agriperlite, zeolite) with 3–5 mm granules was tested on Dieffenbachia 'Carina', Dracaena deremensis 'Warneckii' and Syngonium podophyllum grown in hydroculture. An ebb-and-flood fertigation system with recirculating nutrient solution was used. Data about growth of plants were collected. A synthetic evaluation of ornamental value was assigned to the plants by a score. Growth was satisfactory on all the substrates; best results were obtained with expanded clay or zeolite. Some substrates showed limits from a practical point of view: a) expanded polystyrene resulted very light so every time the nutrient solution was supplied it overflowed from the pot; by the use of a retaining net the stability of the cultivated pots resulted poor and in Dieffenbachia the development of axillary buds from under the substrate level was prevented; b) agriperlite allowed the development of algae on the surface of the substrate; c) zeolite resulted very heavy; plant transport could be not cheap. Productive results in hydroculture were similar or better than the ones obtained with plants grown by traditional technique in an organic substrate supplied with the same nutritive solution used for hydroculture twice a week.