Effects of coffee bean grounds on Urochloa brizantha growth.
The management of invasive plants is strategic for agricultural areas, since these plants lead to a reduction in productivity. Among potential forms of management is the application of coffee grounds, given that the caffeine present in this residue has allelopathic effects. As such, this study's objective was to evaluate Urochloa brizantha growth and phytotoxicity when administering different doses of coffee grounds before and after emergence. The experiment was conducted in a greenhouse of the Federal University of Lavras. Planting of the invasive species employed 8-liter vases with 50 seeds each. Assays were performed using a randomized block design, with three replicates, in a 4×2 factorial scheme. The first factor was coffee ground dosage: 55, 73 and 100 g doses were diluted in 100 mL of water, and each pot received 100 mL of coffee grounds slurry. The second factor was period of application: pre or post-emergence. Evaluated parameters were: plant height; dry shoot mass; phytotoxicity, speed of emergence (SE), and number of emerged plants. We found that pre-emergence treatments significantly reduced the growth of Urochloa brizantha. In respect to the 'SE' and 'number of emerged plants' parameters, slurry with coffee grounds doses up to 50 g were found to compromise plant emergence. In respect to phytotoxicity percentage, a linear increase was observed according to the increase in sludge dosage. This study concludes that, when applied during pre-emergence and in low concentrations, coffee grounds compromise the growth of Urochloa brizantha.