Species that have allelopathic potential are promising in agriculture, with the perspective of identifying their secondary metabolites and manipulating them, for practical applications and, thus, be used to control weeds. In this context, this work aimed to verify the allelopathic effect and identify the secondary metabolites in Canavalia ensiformis species. The Lactuca sativa, Digitaria insularis, Emilia coccinea, and Portulaca oleracea species were used as recipient species. To evaluate the allelopathic potential, the ethanolic extract of the shoot (leaf + stem) of the donor species was carried out. Potential allelopathic effects were evaluated by germination tests and initial seedling growth. The identification of the secondary metabolites of the C. ensiformis shoot was also performed using the high-performance liquid chromatography technique. The ethanolic extract causes germination inhibition and germination speed index of L. sativa. The C. ensiformis shoot contains the compounds belonging to phenolic acids (chlorogenic acid, ferulic acid, and caffeic acid), flavonoids (kaempferol, naringin, and rutin), and carboxylic acids (citric, malonic, and aspartic acids), which can be responsible for the allelopathic activity of this species.Keywords: allelopathy; jack bean; phytochemical. RESUMO ABSTRACTPotencial alelopático e identificação dos metabólitos secundários em extratos de Canavalia ensiformis L. 1As espécies que apresentam potencial alelopático são promissoras na agricultura, ante a perspectiva da identificação e manipulação dos seus metabólitos secundários, para aplicações práticas e, assim, sua utilização no controle de plantas daninhas. Por esta razão, este trabalho teve por objetivo verificar o efeito alelopático e identificar os metabólitos secundários de Canavalia ensiformis L. Sementes de Lactuca sativa, Digitaria insularis, Emilia coccinea e Portulaca oleracea foram utilizadas como receptoras. Para avaliar o potencial alelopático, foi preparado o extrato etanólico da parte aérea (folhas mais caules) da espécie doadora. Os efeitos potencialmente alelopáticos foram avaliados por meio de testes de germinação e crescimento inicial de plântulas. Foi realizada, também, por meio da técnica da Cromatografia Líquida de Alta Eficiência, a identificação dos metabólitos secundários da parte aérea de C. ensiformis. O extrato etanólico causa inibição da percentagem e do índice de velocidade de germinação de L. sativa. A parte aérea de C. ensiformis contém ácidos fenólicos (ácido clorogênico, ácido ferúlico, ácido cafeico), flavonoides (kaempferol, naringina e rutina) e ácidos carboxílicos (ácido cítrico, ácido malônico e ácido aspártico), podendo ser os responsáveis pela atividade alelopática dessa espécie.

The allelopathic potential of some plant species has been scientifically proven over the years. The use of such natural compounds with phytotoxic activity is an alternative to synthetic herbicides. Thus, this research aims to analyze the phytochemical profile and the allelopathic effect of aqueous extracts of Fimbristylis miliacea (L.) Vahl. The allelopathic potential was evaluated by germination bioassays using seeds from two receptor species (Lactuca sativa L. and Emilia fosbergii Nicolson) and seven concentrations of aqueous extracts of F. miliacea aerial and underground parts in triplicate. The variables evaluated were germination (G) andJournal of Agricultural Studies 311 germination speed index (GSI). The data obtained were submitted to F test and the averages to regression analysis. In addition, phytochemical analyses were performed to analyze possible allelochemicals present in aqueous extracts of F. miliacea through phytochemical screening and by high performance liquid chromatography (HPLC). The aqueous extracts of aerial and underground parts of F. miliacea inhibit the germination of E. fosbergii seeds at all concentrations analyzed (0.94, 1.87, 3.75, 7.5, 15 and 30%). However, the same extracts do not show any effects when evaluated in L. sativa seeds. The aqueous extract of F. miliacea shows important chemical constituents (gallic acid, chlorogenic acid, rutin, luteolin, apigenin, acacetin, and alkaloids) that can be directly related to the allelopathic effects observed in E. fosbergii seeds.

The genus Cyperus is widely distributed worldwide and occurs in various regions of Brazil. Research has reported the allelopathic potential of species belonging to this genus. From this perspective, the present study analyzes the phytochemical profile and allelopathic effect of seven concentrations of the aqueous extracts of Cyperus distans L., Cyperus laxus Lam., and Cyperus rotundus L. The allelopathic potential was evaluated in triplicate from germination bioassays on seeds of two species, Lactuca sativa L. and Emilia fosbergii Nicolson. In addition, phytochemical analyses were performed to analyze possible allelochemicals present in aqueous extracts of three species by phytochemical screening and high-performance liquid chromatography (HPLC). The evaluated variables were: germination (G) and germination speed index (GSI). The data obtained were submitted to the F test, and regression analysis was performed to compare means. The results showed higher susceptibility of E. fosbergii to aqueous extracts of C. distans, C. laxus, and C. rotundus at all concentrations analyzed (0.94, 1.87, 3.75, 7.5, 15, and 30%). In turn, the germination rate of L. sativa seeds decreased only at the highest concentrations (between 15 and 30%) of the same extracts. This allelopathic potential may be directly associated with the biosynthetization of phenolic compounds by Cyperus spp., analyzed in this study by phytochemical prospecting and HPLC.