Ação do extrato aquoso das folhas de Azadirachta indica na germinação de Amaranthus viridis

Abstract

Weeds such as Amaranthus viridis (slender amaranth) represent a major threat to agricultural productivity, reinforcing the demand for herbicides. However, due to the environmental and health risks associated with synthetic herbicides, sustainable alternatives such as natural herbicides have gained attention. In this context, plant extracts with allelopathic potential have emerged as a promising tool. This study aimed to evaluate the effects of aqueous leaf extract of neem (Azadirachta indica) on the germination of A. viridis seeds, testing different concentrations under laboratory conditions. The experiment was conducted in a completely randomized design, testing five treatments: a control (distilled water) and four concentrations of neem leaf extract (25%, 50%, 75%, and 100% w/v), with four replicates per treatment. The following parameters were assessed: germination percentage (G%), germination speed index (GSI), mean germination time (MGT), and biomass accumulation (fresh and dry mass of aerial and root parts). The control treatment showed an average germination of 57%, while all neem extract treatments, including the lowest concentration (25%), completely inhibited germination (0%). It is concluded that the aqueous extract of Azadirachta indica leaves has a strong herbicidal potential against A. viridis seeds, fully suppressing germination even at the lowest tested concentration, making it a strong candidate for the development of bioherbicides within integrated weed management strategies.