Allelopathic potential of Dodonaea viscosa (L.) Jacq.

D. viscosa presents the capacity to form dense and dominant populations, being possible the occurrence of allelopathy as one of the strategies in these populations establishment. With the purpose of verifying the existence of allelopathic potential in D.visco sa, germination and initial growth bioassays in Petri dishes were performed, using lettuce as the target plant. The aqueous extracts of D. viscosa dried leaves, at concentrations of 2 and 4%, obtained by static maceration with cold and hot water, were used. As the control, distilled water was used. The pH, osmotic potential and yield of the extracts were determined to exclude non-allelopathic effects. Tannins and saponins were detected in the extracts by qualitative phytochemical reactions. Both extracts prepared with cold water and the 4% extract obtained with hot water affected lettuce germination, altering the total germination, average time, average speed and entropy of treated achene's germination. The lettuce hypocotyl and root development was inhibited by the extracts obtained with hot water. The results indicate the existence of allelopathic potential in D. viscosa.