Efeitos alelopáticos das gramíneas exóticas brachiaria spp e megathyrsus maximum (jacq) b.k. simon & s.w.l. jacobs sobre germinação, desenvolvimento e crescimento de mudas de parapiptadenia rigida (benth.) brenan

Abstract

African grasses as Brachiaria spp. (Braquiária) and Megathyrsus maximum (guinea grass) were introduced accidentally or for fodder purposes and have become invasive of natural ecosystems, going to compete with the native species in places where natural regeneration, such as Parapiptadenia rigida (Benth.) Brenan, popularly known as mimosa-red. Plants growing next to each other, and compete for resources from the environment interact through a physiological process known as allelopathy, which is defined as any direct or indirect alteration, inhibitory or a stimulatory plant on another through alelochimical substances. Therefore, the objective of this study was to determine the groups of secondary metabolites present in braquiária extracts and guinea grass and the allelopathic action of the same on seed germination and development and growth of P. rigida. Through exhaustive extraction using solvents of different polarities were obtained from the leaves of grasses, leaf extracts, ethyl acetate and methanol, and performed the phytochemical screen to identify the presence of certain groups of secondary metabolites in these extracts. Also aqueous extracts were prepared at different dilutions with fresh leaves braquiária and guinea grass. These were evaluated for their ability allelopathic germination and early development and growth of P. rigida seedlings. The results indicate the presence of alkaloids, steroids and triterpenoids, flavonoids, tannins and saponins espumídica in extracts of both weed species. No allopathic interference of aqueous extracts braquiária and guinea grass germination, development or growth of P. rigida was not identified. Therefore, it is possible to recommend the use of P. rigida for reclamation, since, under laboratory conditions and greenhouse, the species showed no inhibition when subjected to extracts of grasses Brachiaria spp. and Megathyrsus maximum.