Adubação nitrogenada e potássica na fisiologia da maturação e propriedades funcionais da banana ‘vitória’

Abstract

Banana farming is a global fruit growing activity, predominant in hot and humid tropical regions with abundant rainfall, including Africa, Latin America, the Caribbean, Asia and the Pacific. However, traditional cultivars are susceptible to diseases and have quality attributes that compromise their commercialization in more competitive markets. Therefore, it is necessary to introduce more resistant and productive cultivars, adjusting production factors, such as fertilization, so that the challenges of meeting current market demands, which require high quality fruits, can be overcome. Therefore, the objective of this study was to evaluate the physiology of maturation and quality fruits of the ‘Vitória’ banana tree introduced in Brejo Paraibano under different combinations of nitrogen and potassium. This work was was carried out in two experiments: In the first experiment, combinations of N and K doses were evaluated to define the ranges that would allow obtaining fruits with attributes of quality more suitable for the market. In the second experiment, in the combinations that provided better quality to the fruits, the functional potential, expression and activity of antioxidant metabolism enzymes were evaluated. The experimental design was that of a plot subdivided over time into randomized blocks, with the plot treatments being two cultivation cycles (1st and 2nd production) and, in the subplot, the treatments were 5 doses of nitrogen N (15; 90; 150; 210 and 285 g plant-1) and 5 potassium K (24; 144; 240; 336 and 456 g plant-1), combined according to the Pan Puebla III matrix. For the first experiment, after harvest, the fruits were evaluated for: respiratory activity, physical, physicochemical, sensory, and functional properties, expression and enzymatic activity. High doses of N provide fruits with greater mass, length, color, brightness, acidity, polyphenol content and antioxidant activity. Combinations of K and N influenced respiratory activity. With a dose corresponding to 285 kg ha-1 of N associated with 24 kg K2O ha-1 of K, the fruits showed higher SS/TA values. Levels corresponding to 210 kg ha-1 of N combined with 336 kg K2O ha-1 and with the highest dose (456 kg K2O ha-1) of K, obtained fruits with greater acceptance by panelists, and better quality attributes, being in these aspects the combinations that best suited the growing conditions in Brejo Paraibano. For the second experiment, higher doses of K reduced the respiratory rate of ‘Vitória’ banana fruits; fruit from plants that received high doses of K had higher ascorbic acid contents; banana ‘that received doses 210N/144K and 285N/336K, showed greater expression and activity of antioxidant enzymes. Altogether, fruits of the banana tree ‘Vitória’ from plants that received a dose of 210N/456K were the best quality and the most accepted in the sensory evaluation.