Soil-less greenhouse production of table grape under Mediterranean conditions.

Soilless culture, widely used for vegetables, flowers and ornamental plants, can be an effective technique to grow table grape and to overcome several issues of the current vineyard production system (i.e. to facilitate variety change, no use of rootstock, extra-seasonal production and improved fruit quality). In this research two greenhouse experiments were carried out in Southern Italy, in a typical area for table grape cultivation, to determine the water consumption, vegetative growth, yield, and quality traits of table grapes grown in a soilless system. The first experiment was a simple comparison of two cultivars Cardinal and Victoria, whereas in the second experiment two cultivars ('Black Magic' and 'Victoria') were grown by using four nutrient solutions characterized by different macronutrient concentrations (100% Hoagland solution type vs 30%-reduced Hoagland: less N and P, or less N, P, Ca and Mg, or less N, P, K, Ca and Mg). In the first experiment, on average, at harvest the yield was 21.7 t ha-1, with a cluster weight of 419 g and 14.9 °Brix. In the second experiment, yield and cluster weight were, on average, 29.4 t ha-1 and 686 g, respectively, and were not affected either by nutrient solution composition or by the cultivar. In both experiments the mean cluster weight and all the organoleptic characteristics were above the European Commission rule n. 2137/2002 limits. These results show that the soilless culture provides table grapes with quality traits completely suitable for international market quality standards, and it is possible to reduce the nutrient concentration of the nutrient solution without negative effects on yield and quality of soilless table grapes.