Young coffee plants are very sensitive to weed interference due to the high nutrient competition among these plants. This work was conducted to evaluate the interference effects of seven weed species on the relative contents (RC) of macro and micro-nutrients in coffee shoot dry matter. At 30 days after coffee seedling transplantation in 12 L pots, the weeds were transplanted to or sowed in those pots (0, 1, 2, 3, 4 and 5 plants per pot). The weedy periods, from weed transplantation or emergence to plant harvesting, were 77 days - Bidens pilosa, 180 days - Commelina diffusa, 82 days - Leonurus sibiricus, 68 days - Nicandra physaloides, 148 days - Richardia brasiliensis and 133 days - Sida rhombifolia. B. pilosa, C. diffusa, L. sibiricus and R. brasiliensis caused considerable decreases in the nutrient RC of the coffee plants, even at low densities. B. pilosa absorved the highest nutrient amounts, while N. physaloides and S. rhombifolia caused the least interference in coffee plants. The degree of interference depended both on the species and density of the weeds.
competition; weedy periods; mineral nutrition
