Aspectos morfológicos e produtivos de cultivares de Urochloa sob adubação nitrogenada

Abstract

The objective of the present research was to evaluate the productive and morphological responsiveness of different genetic materials of Urochloa as a function of nitrogen application. The experiment was carried out in a completely randomized design, in an 8x2 factorial scheme, with 8 cultivars of the Urochloa genus ("Mavuno", "Mulato II", "BRS Ipyporã", "Cayana", "780J", "Sabiá", “Marandú” and “Ruziziensis”) and 2 doses of nitrogen (50 kg/N/ha and 100 kg N ha-1 ), with 4 replications each. In total, 64 beds were used, with dimensions of 10m² (4m x 2.5m) each. The parameters of dry matter yield, canopy height, leaf:stem ratio and yield of forage components were evaluated. The obtained results were submitted to statistical analysis, through the SAS Studio program, with comparison of means by the Tukey test p < 0.05. The parameters evaluated in the present study were not significantly affected by nitrogen fertilization, the differences being restricted only between cultivars. However, the average productivity of the total dry mass (PMST), differed between cultivars and as a function of N doses (P<0.05), so that the greatest effect was due to nitrogen fertilization (P<0.0004). The cultivars fertilized with 100 kg of N ha-1 showed higher DM yields, with average values of 934.4 and 694.6 kg of DM per cut for fertilization with 100 and 50 kg ha-1 , respectively. Among the cultivars evaluated, the highest leaf yields were observed in cultivars Sabiá, Mavuno and 780J.