Effect of chemical weed control in the soybean and maize production system in the floristic community in the Cerrado regions of central Minas Gerais state

Background: The study of the effects of different chemical management practices on the floristic composition of weeds in soybean and maize crops in succession is essential for understanding the population dynamics of the main species present in these cultivated areas. Objective: This study evaluated the impact of different weed control programs on the floristic community in a soybean-maize succession system, in the Cerrado regions of central Minas Gerais state. Methods: Five management systems were compared, ranging from low to high technology levels, including different combinations of herbicides, manual weeding, and winter fallow. The frequencies, densities, dominance, and Importance Value Index (IVI) of weeds were calculated. The similarity index between treatments in the two soybean crops was calculated. Dry biomass (DB) data and total plant density of Commelina benghalensis L. were analyzed at the end of the experiment using geostatistical methods. Results: In all phytosociological surveys, 31 weed species were identified. A predominance of weeds from the Poaceae and Asteraceae families was observed. The highest weed density was observed in the low technology system. Regardless of the technology level adopted, the greatest weed control occurred in the maize crop, reducing the total biomass of the species. In the spatial distribution mapping of C. benghalensis DB, the highest concentration occurred in the low technology system. Conclusions: The greater diversification of herbicides with different mechanisms of action provides less similarity between the weed population in different agricultural crops.