INFLUENCE OF WATER AND NITROGEN AVAILABILITY ON ELEMENTAL COMPOSITION OF PROCESSING TOMATO FRUIT IN EU. COUNTRIES

In order to study the response of processing tomato in two cultural factors under different soil and climatic conditions, the same field experiment was carried out in four Mediterannean countries. Three levels of irrigation water and three levels of Nitrogen fertilizer were applied in a split-plot design experiment. The effect of these treatments on the yield and the quality characteristics of tomato fruits, was studied. Also the effect on the elemental composition of the fruits which is reported in this work, was included in the study. The experiments were carried out in 1992 with the tomato variety. Justar (E6203). In samples of tomato fruits from each experiment, at harvest time, the concentration of N, P, K, Ca and Mg was measured.

Differences in the concentration of mineral nutrients in the fruits, among the sites were found, with the highest differences noticed in P. The concentration of the five nutrients, ranged between 2.36 and 3.70 % for N, 0.29 and 0.65 % for P, 3.22 and 5.33 % for K, 0.12 and 0.21 % for Ca, and 0.15 and 0.29 % for Mg. The effect of water supply level on the mineral composition of the fruits was significant in some cases: Increasing amounts of water resulted in decreased concentration of N, Ca, Mg, P, or K in the fruit, while it resulted in increased concentration of P and Ca in other cases. On the other hand, the increase in nitrogen supply, resulted in an increased concentration of N in the fruits, in four out of six sites while the same trend was noticed in the other two sites. Also increased rates of N supply resulted in a decrease in P or an increase in Ca concentration in the fruit.

Differences in soil condition as it is nutrient availability, PH, organic matter content or soil structure, as well as the climatic conditions resulted in the variation in the response to the same treatments.