Síntese verde de nanopartículas metálicas mediadas por extratos de Endopleura uchi com potencial alelopático: investigando abordagens sustentáveis na agricultura

Abstract

The intensive use of pesticides in agriculture has increased the demand for more sustainable strategies for plant management and for reducing environmental impacts. In this context, the green synthesis of metallic nanoparticles mediated by plant extracts is a promising alternative, as secondary metabolites can act as reducing and stabilizing agents in aqueous media. This study aimed to synthesize silver nanoparticles (AgNPs) mediated by an aqueous stem extract of Endopleura uchi and to evaluate their allelopathic potential in species of agronomic interest. The research included preparation of the plant extract, assessment of its stability by UV-Vis spectroscopy, phytochemical screening, production and stability monitoring of AgNPs, and evaluation of allelopathic activity. The extract showed spectroscopic stability for up to two days after preparation and contained relevant classes of secondary metabolites, including phenolic compounds, flavonoids, tannins, terpenes, saponins, and alkaloids. For AgNP synthesis, the condition pH 8. 0, 30 °C, and 1. 0% extract concentration provided the highest mean absorbance values and better stability over eight days. Type III ANOVA with heteroscedasticity-consistent correction showed that extract concentration was the main source of variation in the system, followed by pH, whereas temperature had no relevant effect within the investigated range. In the germination bioassays, coriander maintained a high final germination percentage in all treatments, with no significant differences, whereas watermelon showed more sensitive responses, particularly in temporal parameters. These findings indicate that E. uchi extract and green-synthesized AgNPs modulate germination in a species-dependent manner, supporting the potential of green nanotechnology as an investigative tool for sustainable agricultural applications.