The experiment was conducted at the Institute of Education, Agriculture, and Environment (IEAA) of the Federal University of Amazonas (UFAM). The aim was to evaluate the allelopathic effect of aqueous extracts of andiroba (Carapa guianensis), copaiba (Copaifera langsdorffii Desf.), cassava (Manihot esculenta), jambu (Acmella brachyglossa Cass.), chicory (Eryngium foetidum), capeba (Piper umbellatum), and amapá (Brosimum potabile Ducke) on the germination of seeds and development of lettuce (Lactuca sativa), onion (Allium cepa), kale (Brassica oleracea), and wheat (Triticum spp.), which served as bioindicators. The leaves of the plants were used to make the extracts that were collected in the municipality of Humaitá - Amazonas and subjected to drying. After drying, the leaves were crushed, and an aqueous extract solution was prepared and added to 600 ml of distilled water. From this dilution, concentrations of 12.5%, 25%, 50%, and 100% were obtained. The experimental design was completely randomized (CRD), with the treatments consisting of four concentrations of the aqueous extract and distilled water (control treatment) in a total of four replicates. Ten seeds were placed per Petri dish for each concentration of the extracts, and the control, on filter paper, and 5 ml of the aqueous extract solution was added. In the control treatment, only distilled water was used as a control. Seven to twelve days after the application of the treatments, the average germinations, radicle length, and aerial part length of the cultures were observed. The evaluated data was subjected to analysis of variance and the Tukey test. The results demonstrated that the aqueous extracts of cassava, andiroba, copaiba, jambu, chicory, amapá, and capeba have inhibition potential on the germination and development of the aerial and radicular parts of lettuce, onion, kale, and wheat.
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