423 Effect of Zeolite and Vine Vinasse on Rose Seedling Growth A. Trinchera, S. Rinaldi, R. Epifani and E. Rea Agricultural Research Council Research Centre for Soil-Plant System Rome Italy Keywords: ornamental plants, root, substrates, scanning electron microscopy, quartz sand Abstract In Italy, the production of ornamental plants in soilless growing media is an important cultivation system in nurseries and rose is one of the most important grown species. One important aspect of cultivation in pot is the selection of the proper substrate for the cultivated variety in order to obtain an adequate nutrition leading to a positive effect on plant quality. The addition of biostimulant substances and organic fertilizers could optimize substrate properties, strongly influencing root development and following nutrients uptake. The objective of this study was to assess the effect of zeolite, alone or in combination with vine vinasse as an organic fertilizer, on rose seedling growth in a model trial. Three varieties of rose, generally produced in Italian nursery, were tested: Fairy The Fairy (FTF), Bright 82 (B82), Double Knock Out (DKO). Granular (0.5-1 mm) or powdered (<30 micron) zeolite were alternatively added to quartz sand, as inert growing substrate, at dose 3% v/v, without or with addition of vine vinasse at concentrations of 1 g L -1 . Rose self-rooted cuttings were transplanted in pots containing the differently added substrates. After 70 days, plant height, number of stems, fresh and dry weight of aerial part, root length, root fresh and dry weight were determined. Interesting results were obtained with FTF variety, being the biometrical parameters significantly influenced by both zeolite and vine vinasse application. In particular, the addition of granular zeolite resulted in a significant increase of plant height and fresh/dry weight respect to the untreated control, while both the powdered zeolite and the granular zeolite with vine vinasse acted preferentially on root parameters; these positive effects were not so evident in B82 and DKO varieties. The addition of zeolite and vine vinasse to the substrate could improve its properties, representing a significant opportunity for optimizing plant root development. INTRODUCTION In Italy, the production of ornamental plants in soilless growing media is an important cultivation system in nurseries and rose is one of the most important species grown. One important aspect of cultivation in pot is the selection of an appropriate substrate for the cultivated variety in order to obtain an adequate nutrition leading to a positive effect on plant quality. The addition of different substances, such as growth promoters, biostimulants and organic fertilizers, could optimize substrate properties by strongly influencing root development and nutrients uptake. Recent studies show that aluminosilicate products, such as clinoptilolite, are not only able to modify soil properties and humic matter characteristics (Filcheva and Tsadilas, 2002) or enhance nutrient slow release when added or coated with mineral fertilizers and/or selected micronutrients (Ferguson et al., 1986; Barbarick et al., 1990), but also to exert a positive effect on root development and robustness, probably due to an increase of mechanical impedance. Changes in root morphology were detected as a severe reduction in root elongation and a corresponding increase in the diameter of impeded roots (Veen and Boone, 1990). Boeuf-Tremblay et al. (1995) further verified that maize seedlings and plant growth were strongly influenced by mechanical impedance simulated by adding glass beads into the sterile growing media, producing roots shorter but heavier per unit of length. This effect, played also by zeolites, Proc. IS on Growing Media, Composting and Substrate Analysis Eds.: F.X. Martínez et al. Acta Hort. 1013, ISHS 2013