Favaliação da atividade alelopática do extrato aquoso de Senna siamea (Lam.) H.S. Irwin & Barneby sobre o desenvolvimento de plântulas de Lactuca sativa l.

Abstract

Allelopathy is understood as a process that occurs in plant communities, where species act through mechanisms capable of interfering with the growth and development of other plants, through the release of chemicals, also called allelochemicals, which are derived from processes that cause they occur naturally in their secondary metabolism and subsequently deposited on the substrate. These allelochemicals may perform harmful or advantageous actions when in contact with other plants present in the same environment, depending on the amount and circumstances in which they are in place. Senna siamea (Lam) H.S. Irwin & Barneby, popularly known as canafistula or cassia-siam is originally from Thailand, but widely found in the Brazilian semiarid region, which has abundant application in landscape use, shading and various ethnopharmacological research. Considering the large dispersal of S. siamea species throughout the Brazilian Northeast, we aimed to evaluate its allelopathic activity on the development of Lactuca sativa (lettuce) seedlings. For this, 25 L. sativa seeds were placed in Petri dishes, and at the same time different concentrations (0, 25, 50, 75 and 100) of the aqueous extract of Senna siamea leaves were added, followed by The seeded plates wererelocated to a germination chamber where they remained for seven days under daily monitoring. The analyzes were performed through measurements of seedling root and hypocotyls and phytotoxicity bioassays and phytochemical tests, from which the presence of secondary metabolites classes such as flavonoids and phenolic compounds were detected. From this, an inhibitory effect was observed in relation to lettuce seedlings, which was observed by observing the root and hypocotyl length, decrease of vigor, presence of necrosis and reduction of chlorophyll and carotenoid content. Based on the knowledge obtained, it is possible to evidence that this plant species has relevant potential as a source of chemical compounds with significant biotechnological properties in the production of natural herbicides for less aggressive use against the weeds, besides the search for more information for proper use of plant species that have allelopathic potential.