Competition of barnyardgrass on soybean cultivated in a hydromorphic soil. I. effect on weed dry matter production and soybean grain yield

Abstract

The aim of this experiment was to study the interaction between competition period of barnyardgrass (Echinochloa spp.) and row spacing on dry matter of the weed and soybean grain yield grown in a hydromorphic soil. The results indicated that barnyardgrass dry matter increased linearly with the competition period whereas soybean grain yield decreased with duration of competition. Reduction of row spacing increased the competition of soybean against the weed. The critical competition period varied between 20 and 50 days after soybean emergence. It was observed that continuous soybean cropping during three years significantly reduced the infestation of banryardgrass and that this reduction has an influence on the critical competition period.