This work was carried out to evaluate the effects of weed densities (low, average and high infestation) on the growth of soybean, cv. BRS-243RR. The experiment was arranged in a completely randomized block design, with the treatments being the periods of competition between the culture and the weeds (0, 0-5, 0-10, 0-15, 0-21, 028, 0 35, 0-42, 0-49 and 0-125 days). The variables evaluated were plant height, dry mass of leaves and branches, number of leaves and leaf area. These evaluations were conducted at the end of each interference period together with weed density and mass accumulation evaluations. When weeds were under low density, a great increase in its density was observed along time, in contrast to the observed under average and high infestation levels, when weed density decreased as a function of days after emergence. Soybean plant height and leaf area were influenced by infestation level but dry mass and number of leaves were not .It was concluded that the level of infestation affects differently the variables that define soybean growth.
Glycine max; competition; weed
