Análise fitoquímica e potencial alelopático de Eragrostis plana Nees (Poaceae)

Abstract

The strategies adopted by invasive plants to dominate the plant community the release of allelochemicals stands. One of invasive species with allelopathic potential and production of these allelochemicals is the capim-annoni-2 (Eragrostis plana Nees). The objective was to verify the allelopathic effect of E. plana on cultivated species (annual ryegrass (Lolium multiflorum Lam.), oat (Avena sativa L.), birdsfoot trefoil (Lotus corniculatus L.), cowpea (Vigna unguiculata L.), sunflower (Helianthus annus L.) and pearl barley (Bromus catharticus Vahl)) and, identifying and quantifying allelochemicals present in the aerial parts of capim-annoni-2. They were collected aerial parts of E. plana, and the dry material in an oven at 60° C for 72 hours and milled to obtain the aqueous extract (allelopathic process) and the ethanol extract (phytochemical analysis) at a concentration of 1 g 10 mL-1. For the allelopathic process, the aqueous extract was diluted in four different concentrations (10, 30, 50 e 70%), using a concentration of 100% (pure extract) and control treatment (distilled water). For the phytochemical process were evaluated by highperformance liquid chromatography (HPLC) the main groups of secondary metabolites with potential allelopathic performances polyphenols (gallic acid, caffeic acid, ellagic acid and chlorogenic acid), flavonoids (quercetin, apigenin and rutin) and total tannins (catechin, apigenin and epicatechin). The allelopathic effect caused decrease in germination of all the tested seeds. There was a greater allelopathic effect as the concentrations of the extract used. The initial root growth and aerial part were reduced with increasing concentrations, whereas the initial growth of these two birdsfoot trefoil structures was inhibited in a concentration of 100%. It is suggested that the allelopathic effect is due to the presence of allelochemicals found in capimannoni-2, being identified and quantified polyphenols (chlorogenic acid and caffeic acid), flavonoids (quercetin and rutin) and total tannins (catechin, apigenin and epicatechin), wherein the first two groups showed up as major components of the grass-2 annoni and could justify the strong dominance of this invasive plant in Bioma Pampa.