791 Medium, Cultivar and Plant Density Influenced Production and Postharvest Shelf-life of Raphanus sativus Grown in a Soilless Culture System Jeanet Hoeberechts, Silvana Nicola, Emanuela Fontana, Daniela Saglietti and Giuseppe Piovano Dipartimento di Agronomia, Selvicoltura e Gestione del Territorio Universit degli Studi di Torino, Grugliasco Italy Keywords: radish, shoot, root, pithiness, weight loss Abstract Soilless culture system (SCS) may be used to produce ready-to-eat radishes. The research was conducted to investigate radish production in a SCS with ebb-and- flow irrigation. Two cultivars (‘French Breakfast 2’ and ‘Jolly’) were grown at two densities (125 and 250 plants/m 2 ) in trays filled with two mixtures of peat, perlite and vermiculite (3.5:1.5:0 and 2.5:1.5:1 v/v/v). Radishes were packaged and refrigerated for postharvest shelf-life (16 days). Commercial root production was significantly influenced by medium x cultivar interaction. With the 2.5:1.5:1 mix, yield reached 1301 g m -2 for 'Jolly' and 826 g m -2 for ‘French Breakfast 2’; with the 3.5:1.5:0 mix, it decreased for both varieties, but more for ‘Jolly’ (799 vs. 795 g m -2 ). The 2.5:1.5:1 mix increased root diameter (18.4 mm) and length (35.0 mm) and decreased number of undeveloped roots (4%) as compared to 3.5:1.5:0 (16.9 mm, 32.1 mm and 10%, respectively). Weight loss during shelf-life was similar for ‘French Breakfast 2’, regardless of the media, while it was greater for ‘Jolly’ grown with 3.5:1.5:0 than with 2.5:1.5:1. Plant density did not influence shelf-life. Radishes may be produced in a SCS with high plant density and a medium mix containing vermiculite. INTRODUCTION The radish (Raphanus sativus L.) commonly diffused in Europe is red with small storage root, short-season vegetable crop normally consumed in salads and other dishes to which it gives color and hot flavor (Bonasia et al., 2001; Curtis, 2003). The edible part originates from the enlargement of the hypocotyl and of the upper part of the root (Marcelis et al., 1997). In Italy, radish is considered a minor crop, whose plantings in 2003 was 774 ha in open field and 229 ha in protected cultivation, producing 12,533 t and 9,035 t, respectively (ISTAT, 2004). In protected and open field cultivation, after harvesting, radish is immediately washed to eliminate soil before it dries, then packaged in bunches of 10-15 roots each, tied with a rubber band, and delivered to the fresh market in boxes (Montalti, 1996). The soilless culture system (SCS) allows to obtain at harvest cleaner radishes that could be commercialized as ready-to-eat foodstuff, packaged without leaves in plastic bags, stored, and displayed in refrigerated stands. Controlling the growing factors in the soilless culture enhances high quality radish production. Radish has good potential to be grown in soilless culture system, as observed by Nicola, et al. (2004); using peat and perlite and ebb-and- flow irrigation, commercial yield was almost twice in comparison with radish grown in soil. In general, one of the key factors of the internal quality of radish roots is pithiness, a physiological disorder characterized by dead cells in which gas embolism is formed, and that may lead to totally hollow roots (Marcelis et al., 1995). Hagiya (1957) reported that pithiness is correlated to a rapid root growth rate and a high root:shoot ratio. Media mix composition for soilless growing systems is important not only for commercial reasons. Media made with different types of component (i.e. peat, vermiculite, perlite) determine the physical and chemical properties of the substrate, thus Proc. VII IS on Prot. Cult. Mild Winter Climates Eds. D.J. Cantliffe, P.J. Stoffella & N. Shaw Acta Hort. 659, ISHS 2004