Incorporation de résidus organiques dans un substrat tourbeux pour la production d'impatiens et de géraniums

During winter 1994 and spring-summer 1994, seedlings of Impatiens wallerana 'Accent Coral' and Pelargonium × hortorum 'Orbit Hot Pink' were grown in a commercial substrate (PRO-MIX 'BX') or in one of 24 substrates composed of perlite (35% by volume), peat moss and of six organic residues (composted water-treated sludge, forestry compost, fresh or composted used peat extracted by biofilter during treatment of municipal water, and fresh or composted paper sludge). The purpose of the study was to determine the maximal proportion of these residues to be incorporated into a peat substrate to obtain quality plants. Growth parameters (growth index, top dry weight, and visual quality) generally decreased with increasing proportion (5, 10, 25 or 40% per volume). During the winter experiment, growth of control plants was superior to growth of plants grown in substrates composed of residues. An incorporated proportion of 25% per volume was shown to be maximal for the production of impatiens and geraniums. Key words: Impatiens wallerana, Pelargonium × hortorum, water treated sludge, composted wastes, peat moss, subirrigation