Effects of different nitrogen sources and levels on tomato fruit quality

The use of nitrogen fertilizers contributes significantly to the proper growth and development of tomato plants, with significant gains in the production of fruit. However, incorrect use of nitrogen can change tomato fruit quality, making it undesirable for consumers. The aim of this work was to study the effect of different sources and levels of nitrogen on tomato quality to improve N management. The field experiment was conducted at the State University of Southwest Bahia - Vitória da Conquista, Bahia, Brazil. The experimental design was a randomized block with 4 replicates, with three nitrogen sources (calcium nitrate, ammonium sulfate and urea) and four levels of nitrogen (0, 140, 280 and 420 kg ha^-1) in a 3×4 factorial. Fruit from the experimental treatments were evaluated for the following characteristics: firmness, pulp pH, titrate able acidity of the juice, ascorbic acid, soluble solids and the ratio of these. Increased levels of nitrogen negatively influenced the levels of ascorbic acid and titrate able acidity. The values of soluble solids and pH did not change with increasing nitrogen level, showing different effects in the sources used only. Due to effects several of different nitrogen sources on fruit quality characteristics, fertilization practices using nitrate and ammonium are recommended in order to improve quality.