Impact of Nitrogen Fertilization on Nutrient Content of 'Paluma' Guavas During Fruit Development: A Target Metabolite Approach

Guava (Psidium guajava L.) is a tropical fruit with significant economic potential due to its in natura and industrialized consumption. This fruit has a high nutritional value due to bioactive substances, such as high levels of vitamins and carotenoids. Our study evaluated the impact of varying levels of nitrogen fertilization on the development of guava fruits over a set of targeted metabolites. For this purpose, guava plants were fertilized with 500, 1000, and 2000 g N2/tree, and their fruits were evaluated at four stages of development. In all stages, the diameter of the fruits was measured, and the pH and soluble solids were analyzed. Capillary electrophoresis was used to determine the concentrations of neutral sugars and ascorbic acid. High-performance liquid chromatography was used for β-carotene analysis. The study observed that nitrogen fertilization did not change the size of the fruits, but the highest concentration of fertilizer (2000 g N2/tree) reduced the concentrations of ascorbic acid and β-carotene. These results concluded that the intermediate fertilization level (1000 g N2/ tree) produced most of the metabolite levels studied, in contrast to the highest nitrogen level applied, which showed similar behavior to the absence of fertilization. Correct nitrogen fertilization plays a fundamental role in producing high-quality fruits, influencing the content of various metabolites produced by the fruits. Therefore, adjusting fertilization practices according to the specific needs of their crops helps produce valuable fruits. Meanwhile, incorrect nitrogen fertilization generates direct costs for farmers regarding lost production and imposes significant costs on the environment and society.