Sorghum bicolor como fonte de compostos alelopáticos para o manejo sustentável de Bidens pilosa

Abstract

Blackjack (Bidens pilosa) is among the main invasive weeds in tropical agricultural systems, exhibiting high competitive ability and an increasing occurrence of herbicide-resistant biotypes. In this context, the use of allelopathic compounds of plant origin emerges as a sustainable alternative for weed management. The present study aimed to evaluate the allelopathic potential of sorghum (Sorghum bicolor) extract on the germination and early development of Bidens pilosa seedlings. The experiment was conducted in a completely randomized design, with six concentrations of sorghum extract (0, 10, 20, 40, 80, and 100%) and five replications. Germination (G), germination speed index (GSI), mean germination time (MGT), hypocotyl length (HL), radicle length (RL), fresh mass (FM), and dry mass (DM) of the seedlings were evaluated. The extract concentrations significantly affected germination, seedling vigor, and early growth. The sorghum extract promoted concentration-dependent responses. Lower concentrations stimulated some characteristics related to germination and early growth, whereas higher concentrations reduced germination, vigor, and biomass accumulation. Radicle length showed high sensitivity to the extract, with a progressive reduction as extract concentration increased. The 50% inhibitory concentration (IC₅₀) for radicle growth was estimated at 34.67% extract. The results demonstrate that sorghum extract has allelopathic and bioherbicidal potential against Bidens pilosa, and may constitute a complementary tool for sustainable weed management.