1115 The Effect of Grape Marc Compost on Pot Culture of Selected Woody Ornamental Species R. Madjar 1 , V. Davidescu 1 , M. Dumitraşcu 2 , C. Mănescu 2 and A. Peticilă 2 1 Faculty of Agriculture, Romania 2 Faculty of Horticulture, Romania 59 Blvd. Mărăşti, District 1, 011464, Bucharest Romania Keywords: substrate, pot culture, plant growth, mineral nutrition dynamics Abstract A challenge in pot culture technology is to find sources of cheap, but superior quality substrates. The high prices of substrates increase the production costs of the final product and make it less affordable to consumers. Furthermore, the increasing restrictions on peat exploitation in European countries have necessitated research into finding alternative organic materials as suitable substrates. This study aimed to investigate the effect of grape marc compost as an alternative composite for potted culture of four woody ornamental species and cultivars. For this, the marc grape compost was mixed with leaf compost, forestry compost and peat. Starting only in the second year of cultivation, plants were fertilized with a Coïc solution during the vegetative growth phase. The mineral content of the substrate as well as the growth response of the plants to fertilization were reported. INTRODUCTION Within the technology of potted ornamentals, soil is gradually being replaced with other substrates, mostly organic materials. These substrates need to ensure a steady supply of water and nutrients to the root system. Although natural substrates such as peat, manure, leaf compost, forestry compost and waste compost are rich in organic matter and microbial flora, their physical and mechanical structure are unstable (Aendekerk, 1997; Davidescu et al., 2003). Therefore, considering that plants require certain soil physical and chemical properties, it is important to evaluate the composition of a substrate for its suitability for each species or cultivar (Madjar et al., 2007). The aim of this research was therefore to study aspects of the nutrient dynamics of a grape marc-based compost and to evaluate the plants’ growth responses to a standard commercial fertilization regime, as would be used in conjunction with conventional substrates (Charpentier et al., 2001; Niers, 1982). Detailed studies that provide a greater understanding of the agrochemical properties of different substrates produced from recycled organic waste will contribute significantly to the decontamination of the environ- ment, as such studies promote the use of these recycled organic substrates for woody plant production (Madjar et al., 2008; Rosel, 2006). MATERIALS AND METHODS Young plants of four ornamental plant species and cultivars, namely Tamarix tetrandra, Ligustrum ovalifolium ‘Aureum’, Chamaecyparis pisifera ‘Boulevard’ and Chamaecyparis lawsoniana ‘Stardust’, were planted in 2008 into a mixture containing leaf compost, forestry compost, peat and marc compost, in a 1:1:1:0.5 ratio. In the first year after planting, the potted plants were maintained without any fertilization. In the summer months of the second year of cultivation, a treatment group was fertilized, three times during this period, with a commercial Coïc solution (Lesaint and Coïc, 1983), whereas a control group remained unfertilized (Table 1). Plant growth, quantified in terms of plant height- and diameter, were recorded monthly during the growing season. In addition, both the leaf material and substrates were analyzed for dry matter content respectively, together with the pH, levels of soluble salts and soluble forms of nitrogen, phosphorus, potassium, calcium and magnesium. Statistical correlations between the plant Proc. XXVIII th IHC – IS on Adv. in Ornamentals, Landscape & Urban Hort. Ed.: G. Groening Acta Hort. 937, ISHS 2012