Modelling Competition between Large Crabgrass and Glyphosate-resistant Soybean in the Rolling Pampas of Argentina

摘要

Large crabgrass is considered among the ten most important weeds in Argentina, especially in no-tillage fields, and is one of the most troublesome weeds in soybean. A field experiment was conducted in the Rolling Pampas, Argentina area under a no-tillage system to establish the competition relationship between large crabgrass ( Digitaria sanguinalis (L.) Scop.) and glyphosate-resistant soybean ( Glycine max (L.) Merr.). Hyperbolic and exponential models were compared to model the effect of large crabgrass density and biomass on soybean yield. The hyperbolic model represented these relationships better than the exponential model. Weed-biomass models showed a better prediction than weed-density models. Results showed that approximately 50% of soybean yield loss was reached with 4±1 plants m^-2 or with 256.20±34.45 g dry matter m^-2 of Digitaria sanguinalis .