The estimulant effect of nitrogen and subrates of herbicides on the nitrogen level and yield of wheat was studied in two field experiments. Nitrogen, as ammonium sulfate, was applied at 0, 30 and 60 kg/ha in the first experiment (1977) and at 0, 50 and 100 kg/ha in the second one (1978), being a third part at seeding and the remaining at the flower set begining. At this stage, simazine at 280 g/ha, metribuzin at 75 and 90 g/ha and bromacil at 140 g/ha, were also applied on the wheat plants. The effect of these treatments were evaluated through grain yield, N and S content in the grains, N content in the flag leave, at 52 and 72 days after seeding, and number and weight of the grains of 20 ears. The yield was not affected by the N applications in both experiments. Exception for metribuzin at 75 g/ha, the other herbicide treatments reduced yield in both experiments. The N fertilization enhanced significantly the N content in the flag leave and the content of N and S in the grains. These parameters were not in fluenced with the herbicide applications, excepting simazine and bromacil, which caused N content decrease in grains in the second experiment. In both experiments the number and weig ht of grains from 20 ears were not affected by N levels or herbicides, except for bromacil, which reduced these values in the second one.
herbicide subrates; N levels; wheat; N and S content