Towards the Optimal Mineral N Fertilization for Improving Peeled Tomato Quality Grown in Southern Italy

Nitrogen (N) fertilization has often been used in excess by farmers to improve commercial yield and the profitability of processing tomato crops. However, N fertilizers greatly affect the overall tomato quality, including technological traits, nutritional characteristics, and mineral fruit composition. The aim of this work was to study the effects of increasing mineral N fertilization rates on processing tomato yield and quality when grown in Southern Italy conditions. The study was carried out at Battipaglia (Southern Italy) cropping cultivar “Messapico”, suitable for peeled tomato, and fruit quality was evaluated at the ripening stage. Results showed that N fertilization reduced sunburned fruits and resulted in increasing total yield, average fruit weight, as well as other fruit parameters (size, firmness, color indexes, pH, N, and calcium content). On the other hand, N fertilization negatively affected other fruit traits, such as dry matter and soluble solids content, total sugar index, ascorbic acid, and sodium content, while it had no effect on potassium and magnesium concentration in tomato fruits. Our results show that, in the investigated area, 200 kg N ha−1 is the best compromise to satisfy farmers and processors expectations, improve yield, and at the same time maintain good fruit quality attributes