Acacia concinna (Willd,) DC. (Fabaceae) has been used as a traditional medicine and well-known for many of their pharmacological and toxicological properties. However, the allelopathic property of the plant have not yet been evaluated. Therefore, we investigated the allelopathic activity of Acacia concinna pods. Aqueous methanol extracts of A. concinna pods inhibited the growth of cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), rapeseed (Brassica napus), barnyard grass (Echinochloa crus-gallis L.), Italian ryegrass (Lolium multiflorum Lum.), foxtail fescue (Vulpia myuros (L.) C. C. Gmel.) and timothy (Phleum pretense L.) at concentrations greater than 0.003 and 0.001 g dry weight equivalent extract/mL for their shoots and roots, respectively. The inhibitory effect was increased with increasing the concentration of the pod extracts. The concentrations required for 50% inhibition of shoot and root growth of the eight test plant species ranged between 1.00 to 5.17 and 0.02 to 2.59 g dry weight equivalent extract/mL, respectively. Root growth of all test plant species were more sensitive to the extract than shoot growth of them. The extract was purified by column chromatographies and reverse phase HPLC, and an active substance (ACP-1) was isolated. The present result indicates that A. concinna has allelopathic activity and ACP-1 may be responsible for the allelopathic effect of A. concinna. The pods and the pod extracts of A. concinna could be useful for one of the weed management options.
Key words: Acacia concinna, allelopathic activity, medicinal plant, inhibitory effect, alternative weed management
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