INFLUENCE OF WATER AND NITROGEN AVAILABILITY ON YIELD AND QUALITY OF PROCESSING TOMATO IN THE EUROPEAN UNION COUNTRIES

A study of the influence of water and nitrogen availability on yield components and quality components of processing tomato began in 1991 for 3 years with the financial support of the Commission of the European Union. A coordinated network of experiments was set up in France, Greece, Italy, Portugal and Spain. The defined crop context was mechanized, single passage harvest for paste manufacture.

Through a joint protocol in 6 locations, 3 differentiated rates of irrigation by aspersion and 3 differentiated rates of nitrogen supply were applied using a split-plot design (4 replications). During the crop cycle numerous measurements and observations were taken: main characteristics of climate, soil (changes in water and nitrate concentration), plants (growth and development). At harvest time, yield components were measured and the main red fruit characteristics were analysed (soluble and total solids concentration, pII, acidity, colour, firmness, mineral composition).

General results for the whole design are presented. The experimental treatments have resulted in differentiated changes of soil water and nitrate concentration in the various locations. The water factor had an important influence on the yield components and on the main characteristics of technological quality. On the contrary the nitrogen factor has had very little influence on these variables. Among other results, an inverse relationship between soluble solids concentration and yield was noticed. Detailed results have been related in several other papers in the same issue.