Allelopathic effects of Brachiaria ruziziensis and aconitic acid on Ipomoea triloba weed

This study investigated the allelopathic potential of both aqueous fraction of Bracharia ruziziensis L. straws and trans-aconitic acid, a component of aqueous fraction on growth and physiological processes of the weed Ipomoea triloba L. Both aqueous fraction and aconitic acid at 250–2000 ppm concentrations influenced the germination and growth of I. triloba and caused similar changes in the respiratory activity of primary roots. They reduced KCN-sensitive respiration and increased the KCN-insensitive respiration. The highest concentration of both aqueous fraction and trans-aconitic acid increased the malondialdehyde and conjugated diene content in the primary roots of seedlings. The oxygen consumption from citrate oxidation in mitochondria isolated from primary roots was not affected. Thus, the water soluble compounds of B. ruziziensis were phytotoxic to I. triloba, inducing perturbations in respiratory activity and lipid peroxidation. Although trans-aconitic acid exerted similar effects to the aqueous fraction, it is not the main compound responsible for the effects of aqueous fraction in I. triloba, because its content is very little in this fraction.