Metabolic Response of ‘Topaz’ Apple Fruit to Minimal Application of Nitrogen during Cell Enlargement Stage

Nitrogen is an integral element of foliar sprays during apple fruit formation. However, in red cultivars, the application may have adverse effects on color second stage development. The effect a low-dose urea was monitored ‘Topaz’ pomometric (fruit mass, firmness, total solids, starch content, skin color) and biochemical traits (primary metabolites, phenolic compounds, assimilatory pigments). Three applications (17 July, 27 18 August) two different doses (N1 = 1.4 kg N ha?1; N4 4 ha?1) control (N0, only sprayed with water) were used. Low did not affect flesh soluble, solid, but individual mass significantly higher N1 treatment compared to other treatments. Significantly lower a* parameters content anthocyanins measured apples subject treatment. Many secondary metabolites (phenolic acids, flavan-3-ols, flavonols, chalcones) also negatively affected by application. Conversely, treatments increased pigments skin. Even minor levels nitrogen, applied directly leaf at later stages development, altered composition metabolites.