The objective of this study was to evaluate the influence of nitrogen application time on weed interference in maize and to determine nitrogen application effect on weed control. The trial was conducted in completely randomized blocks and split-plot design, with four replications. The treatments consisted of five systems of nitrogen application on maize: 0-0-0, 150-0-0, 75-75-0, 0-150-0 and 0-75-75, corresponding, respectively, to the applied amounts of nitrogen before sowing with four and eight leaves, and six times of weed control (maize with 2, 3, 4, 5, 6 and 7 leaves) plus two controls with and without the presence of weeds. The chemical control of weeds was performed after emergence by associating the herbicides nicosulfuron and atrazine. The weed control in V2 was not efficient due to re-infestation. Anticipated applications of nitrogen increased weed density. The greatest nitrogen levels in the index-leaf occurred when nitrogen was applied in V4 and V8, regardless of weed control time. The highest grain yield and number by corn ear were obtained after weed control was performed at the phenological stage V, regardless of nitrogen application time.
Zea mays; management; interference; fertilization
