Atividade da urease em capim-Marandu após aplicação de doses de ureia

Abstract

Urease is an enzyme that catalyzes the hydrolysis of urea to carbon dioxide and ammonia. Thus, the distribution of urease and the factors that influence it are of great importance related to the use of urea in agriculture. The objective was to evaluate the enzymatic activity of urease in LR leaves (newly expanded leaf blades) of Marandu grass after the application of different doses of nitrogen, using urea as a source. The experiment was installed on September 29, 2020. The area where the experiment was installed in 2009 was converted from a native area to land use and, prior to the installation of the experiment, the area had already been cultivated with other Brachiaria brizantha pastures. The area is located at UFMT, Barra do Garças/MT, located under the coordinates 15°52'28.64"S and 52°18'36.86"W. The experimental design used was randomized blocks with six doses of N: 0, 60, 120, 180, 240 and 300 kg ha-1 of N from urea (45% N) and four replications with 24 experimental plots. The application of urea in the treatments was split in two for those above 120 kg ha-1, with 50% of the dose on February 15, 2022 and 50% on February 25, 2022. To carry out the test of urease, the LR fraction (newly expanded leaf blades) was collected and taken to the laboratory for the procedures. Data were submitted to analysis of variance using the F test and, when significant, regression tests were performed using the SISVAR 4.6 statistical program. In which it was observed that the higher the applied dose of N, the lower the urease activity.