Cordia oncocalyx (Allemão) Baill. (Boraginaceae) Chemical Composition and Alelopathic Effect Against Weeds

Through secondary metabolism, plants produce chemical compounds which when released into the environment can have effects on other species, such effect is called allelopathy. In this research we evaluated the Cordia oncocalyx (Boraginaceae) allelopathic potential against two weed species, Cenchrus echinatus and Calotropis procera, as well as quantified its phenolic compounds using HPLC-DAD. The experimental design was completely randomized with six treatments and one control group (distilled water). Each treatment consisted of four replicates with 25 seeds each, totaling 100 seeds per treatment. The variables analyzed were: germinating potential, germination velocity and seedling development. The hot and cold infusion extracts were prepared with 50 g of each of the three parts of the donor plant (bark, leaves and roots) immersed in 500 ml of distilled water at 100 °C (hot infusion) and 25 °C (cold infusion). The experiments were mounted in Petri dishes having substrate filter paper embedded in 3 mL of the extracts (treatments) and conducted in a germination chamber. Hot and cold infusion extracts of the C. oncocalyx leaves, barks and roots presented allelopathic activity on C. echinatus and C. procera germination and development, with the hot bark extract promoting such effect with a greater intensity. The allelopathic effect observed may be due to the presence of allelochemicals such as caffeic acid, quercentin and kaempferol present in C. oncocalyx leaves, barks and roots.