Allelopathic Influence of Aqueous Extract of Stachytarpheta cayennensis (Rich.) Vahl on Seed Germination and Initial Seedling Growth of Cucumis sativus L.

Allelopathy studies investigate the positive and negative effects that secondary metabolites of plants, microorganisms or fungi on the development of neighboring individuals. This study aimed to evaluate the allelopathic potential of aqueous extracts of Stachytarpheta cayennensis on germination and initial development of Cucumis sativus L. seedlings variety. For this, the experiment was performed in the laboratory, using 5 concentrations (0, 5, 10, 20 and 40%) of the extracts, with 4 replicates each. The cucumber seeds were distributed in gerbox boxes lined with germitest paper, totaling 25 seeds per replicate. Subsequently, they were moistened with the extracts and kept inside the BOD-type germination chamber, regulated to 26°C and 12 hours brightness, following the completely randomized design for 7 days, and the control, for comparison purposes, was used distilled water. Comparing the zero dose to the other concentrations, the interferences in the GVI (germination velocity index) occurred in a greater proportion in the macerated stem concentrates diluted from 20%. Regarding MGT (mean germination time), the results point to interferences in this variable, in stem and leaf concentrates. Differential behaviors were observed when analyzing root and shoot length of seedlings, where macerated root extracts caused reduction as the doses increased. Extracts of stem showed increase of these variables as the doses increased. In leaf concentrates the result remained stable at shoot length and in smaller proportions regarding the root length of C. sativus seedlings. For dry matter, the leaf and stem concentrates increased this variable, while the root extracts had a reducing effect, remaining stable at 20%. The survey of the allelopathic potential of S. cayennensis contributes significantly with information of these plants considered as spontaneous and improve studies of the biological properties in the scientific community.