The objective of this experiment was to evaluate the morphogenetic traits and biomass accumulation of Brachiaria brizantha cv. Xaraés subjected to doses of N (0, 125, 250, 375 and 500 kg.ha-1 N). The treatments were arranged in a completely randomized design with four replications. Morphogenetic traits and biomass accumulation of dry matter (DM).ha-1 were evaluated. The results were subjected to statistical analysis by grouping the data in two periods, rainy season and throughout the year. Nitrogen doses influenced leaf appearance in the rainy season and throughout the year, with significant increase in leaf elongation during the rainy season, an increase of 56% compared with control. During this period, maximum dose of N (248.1 kg.ha-1) produced 214.49 kg.ha-1.day-1 DM of leaf blade, which was 133% higher than the control. However, the higher N dose in the rainy season resulted in an increase of 137% in the stalk accumulation compared with non-fertilized grass; estimating maximum accumulation of salk of 84.97 kg.ha-1.day-1 of DM for the application of 326.2 kg.ha-1 N. Doses of N also intensified leaf senescence during the rainy season and throughout the year. The control treatment presented 32% less senescence compared with maximum N dose (270.1 kg.ha-1 N) in the rainy season. Forage loss was estimated at 26.08 kg ha-1.day-1 DM at the maximum dose of 295.0 kg.ha-1 N for this period. All variables studied responded positively to N supply in the rainy season. The accumulation of biomass of the plant reached the maximum point with fertilization close to 250 kg.ha-1 N in the rainy season and 375 kg.ha-1 N throughout the year.

Neste trabalho, objetivou-se avaliar o efeito de diferentes doses de silicato de cálcio sobre a população de ninfas de percevejo castanho das raízes em Brachiaria brizantha, nas características químicas do solo, planta e produção de matéria seca. O experimento foi conduzido em blocos casualizados, com cinco tratamentos e quatro repetições, totalizando 20 parcelas. Os tratamentos testados foram cinco doses (0, 0,5, 1, 2, e 4 t ha-1) de silicato de cálcio aplicadas junto com a adubação NPK na implantação da B. brizantha. Foi avaliado o número de ninfas do percevejo (profundidade de 0 a 40 cm), o pH e os teores de cálcio e de silício no solo. Aos 120 dias do plantio, a gramínea foi cortada, determinando-se a composição química e a produção de massa seca. Verificou-se que a aplicação de 2,6 t ha-1 de silicato de cálcio foi a melhor dosagem estimada para a redução de ninfas do percevejo castanho das raízes. A aplicação de doses crescentes de silicato de cálcio no solo promoveu o incremento do pH, dos teores de cálcio e silício no solo e o aumento na produção de matéria seca de B. brizantha.

The objective of this study was to evaluate the effects of different calcium silicate rates on the nymph population of the brown root stinkbug in B. brizantha cv. marandu, in the soil chemical characteristics, and plant and dry matter production. The experiment was carried out in casualized blocks with five treatments and four repetitions, in a total of 20 plots. The treatments tested were five rates (0, 0.5, 1, 2, and 4 t ha -1) of calcium silicate applied together with NPK fertilization in the implantation of B. brizantha. The nymph number (depths 0 to 40 cm), pH, and soil calcium and silicon content were evaluated. On the 120th day after sowing, the grass was cut to determine the chemical composition and dry matter production. It was verified that the application of 2.6 t ha -1 of calcium silicate was the best estimated rate for the reduction of brown root stinkbug nymphs. The application of increasing doses of calcium silicate in the soil caused an increase of the pH, calcium and silicon content in the soil, and an increase in B. brizantha dry matter production.