735 Effects of Plastic Screens on Virus Infection, Yield and Qualitative Characteristics of Small Tomatoes I. Giordano and A. Pentangelo Istituto Sperimentale per le Colture Industriali S. S. 18, n 156  84091 Battipaglia (SA), Italy. e-mail: iscibattipaglia@tiscalinet.it G. Graziani and V. Fogliano Dipartimento di Scienza degli Alimenti, Universit di Napoli "Federico II", Parco Gussone - 80055 Portici (NA), Italy L. Gennaro INRAN, Via Ardeatina 546, Roma - Italy Keywords: Plastic screens, insects, virus, carotenoids, flavonoids, nutritional quality. Abstract The covering of crops with plastic screens has increased during last years for their protective capacity against vegetable insect pests and virus. To investigate if crop covering can also affect yield level and fruit nutritional quality, we have compared two small tomato varieties (“Corbarino” and “Faino”) cultivated in open field and under high tunnel made by two types of covering tissue: a white, 90% transparent tissue (“anti-aphid net”) and a “non-woven fabric” (“t-nt”). The “t-nt”, which has a closer mesh than “anti-aphid net”, proves to be efficient against both pathogens CMV and TSWV, while the other is only effective against CMV. Both covering tissues led to a 30% average reduction of the light intensity; to a rise of 10% in the production yield; to an increase of fruit weight and to a more uniform size of the fruits with respect to the control. Carotenoids concentration in “Corbarino” increased by about 20% with both types of covering tissues, while it remained unchanged in “Faino”. Flavonoids concentration was not affected in both varieties. The data on carotenoids were confirmed by a corresponding increase observed only for “Corbarino” tomatoes in the lipophilic antioxidant activity. INTRODUCTION Tomatoes represent by far the most important contributor of dietary lycopene and some flavonoids can also be found in significant amounts (Beecher, 1998). In the typical area of S. Marzano tomatoes many small tomato ecotypes are cultivated: the most typical, with oval or elongated-pear shaped fruits and average weight between 10 and 20 g, are known as Pomodorino di Corbara or Corbarino (De Cillis, 1962; Giordano et al., 1999). Cucumber Mosaic Virus Cucumovirus (CMV) and Tomato Spotted Wilt Virus Tospovirus (TSWV) are the main virus responsible for serious tomato phytopathologies in Southern Italy (Gallitelli et al., 1988; Ragozzino, 1995). The first one is transmitted in a non-persistent way by a great number of aphid species, while TSWV vectors are thysanopterous of Thripidae family. Within the different defence strategies, good results have been achieved using crop covering materials (Pentangelo et al., 1999). The aim of this work is to verify the protective efficacy of some covering materials of tomato plants against main virus vectors also evaluating their influence on the productivity and qualitative and nutritional side of fresh product. MATERIALS AND METHODS Tomato Sampling and Cultivation The trial (performed in 1999) compared two covering materials (anti-aphid net and non-woven net) together with a control without any protection. The anti-aphid net was made of white, 90% transparent tissue, with a weight of about 105 g m-2, and a 20/10 mesh (20 horizontal and 10 vertical threads cm-2). The other screen was the Proc. 6 th IS on Protected Cult. Eds: G. La Malfa et al. Acta Hort 614, ISHS 2003