Allelopathic activity of Acacia concinna pod extracts

Abstract

Acacia concinna (Willd.) DC. (Fabaceae) has been used as a traditional medicine and its pharmacological and toxicological properties are well-known. However, no study has reported on its allelopathic property. In this study, the pod of A. concinna was extracted with aqueous methanol to investigate for allelopathic activity and for the isolation of allelopathic substances. Result showed that A. concinna pod extracts inhibited the growth of shoots and roots 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 Lam.), foxtail fescue (Vulpia myuros (L.) C. C. Gmel.) and timothy (Phleum pretense L.) at concentration of 3 and 1 mg dry weight equivalent extract/mL, respectively. The growth decrease as the concentration of the pod extracts increase. The I/50 values of test plant shoots and roots ranged between 1.00-5.17 and 0.02-2.59 mg dry weight equivalent extract/mL, respectively. The inhibition on the roots was stronger than the shoots of test plants. The pod extracts were purified by column chromatographies and the inhibitory substance ACP-1 was isolated which inhibited the shoots and roots of cress by 27.1 and 14.4% of control length, respectively. Results indicated that the pod of A. concinna has allelopathic activity and ACP-1 may cause this activity. The pods and pod extracts of A. concinna could, therefore, be utilized for weed management and control.