With the objective of veryfing the response of different doses in species of weeds by herbicide glyphosate, an experiment was conducted in growth chamber in a completetly randomized design with three repetitions, in the Department of Vegetable Production at ESALQ/USP. For that, were chosen six species of weeds: Bidens pilosa L., Tridax procumbens L., Digitaria insularis (L.) Feed, Spermacoce latifolia Aubl., Ipomoea grandifolia L. and Commelina benghalensis L. The herbicide glyphosate, inhibitor of the enzyme EPSPs, was used at rate 0.0; 11.3; 22.5; 45; 90; 180; 360; 720 and 1440 g.ha-1 a.i. Curves of dose-response were made by the adjustment of the equation of the collected data of green biomass using the log-logistic model: Y = C+D-C / 1 + Exp{b[log(x)-log(RC50)]}, calculated by the no linear statistical model through the SAS statistical program. After the determination of the dose-response curves for the species mentioned above the Bidens pilosa was considered the most susceptible weed to glyphosate, showing the houvest RC50 (31.86 g.ha-1 a.i.). The species Tridax procumbens, Digitaria insularis, Spermacoce latifolia, Ipomoea grandifolia and Commelina benghalensis obtained RC50 equal to 58.40; 128.50; 250.44; 615.49 and > 1440.00 g.ha-1 a.i., respectively, what means that the necessary amount of herbicide to reduce in 50% the green biomass was 1.83; 4.03; 7.86; 19.31 and >359.56 times higher in relation the Bidens pilosa.
response doses; Spermacoce latifolia; Tridax procumbens; Commelina benghalensis
