Nitrogen and potassium supplied by phenological stages affect the carotenoid and nutritive content of the tomato fruit

Abstract

The effect of nitrogen (N) and potassium (K) supply by phenological stages of horticultural crops such as tomato has been little explored so far. In this study, we evaluated the impact of N supply in the vegetative stage and K in the reproductive stage of tomato, on the carotenoid and nutritive content of fruits of three truss clusters. The concentrations of protein, lycopene, β-carotene, sugars, vitamin C and fruit juice were affected by the N and K application by phenological stages, although the N×K interaction was not significant in the last three variables. Increases in N from 10 to 16 molc m-3 of nutrient solution (NS) in the vegetative stage of the crop increased the concentrations of protein, vitamin C, sugars (temporarily) and fruit juice. Likewise, increases in potassium (5 to 13 molc m-3 NS) in the reproductive stage of the crop raised the concentrations of sugars, vitamin C, protein, lycopene, β-carotene and fruit juice. The concentration of carotenoids and the nutritional value of the tomato fruit were influenced by N and K nutrition by phenological stages, and these effects change slightly depending on the cluster harvested and the temperature during the growing cycle.