Atributos químicos do solo, produção e fisiologia da couve-flor sob doses e épocas de aplicação de ácido fúlvico

Abstract

Among the humic substances, fulvic acid promotes the growth of roots, shoots and leaves, in addition to increasing the chlorophyll content, photosynthesis, and ATP production. Therefore, the objective was to evaluate the effects of doses of fulvic acid on cauliflower (Brassica oleracea L. var. botrytis) aiming to improve agronomic aspects of the crop. The experiment was carried out between the years 2022 and 2023, in an open field, at the company Canteiro Cheiro Verde, located in the municipality of Nova Floresta - PB, microregion of Curimataú Paraibano. The design used was in randomized blocks, organized in a 4 x 3 factorial scheme, with four doses of fulvic acid (0; 20; 40 and 60 L ha-1) divided into three fractions: the first fraction was the total application of doses at 28 days after transplantation (DAT); second fraction corresponds to the application of 50% at 14 and 50% of doses at 28 (DAT); and the third fractionation will be done with 7, 14, and 28 (DAT), corresponding to the percentage of 20%, 20% and 60% of doses, respectively. Analyzes of wet mass, dry mass, and nutritional content of the inflorescence and leaves, growth and physiological analyzes of the plants and chemical analysis of the soil were carried out. For soil fertility attributes, doses of fulvic acid only influenced the pH, decreasing when the application was without fractionation. The nitrogen content of the leaf was significantly influenced by the dose of 20 L ha-1 of fulvic acid, with fractionation 2 (applied twice). Fractionation 3 is the one that maximizes the physiological variables. Productivity was higher at dose of 60 L ha-1 of fulvic acid when fractionation 3 was used.