Abstract

Coccinia grandis L. (Cucurbitaceae) is a tropical vine that grows densely and suppresses the growth of surrounding plant species. The glabrous leaves and fruits of this plant have long been used as traditional medicine. The pharmacological property of C. grandis is notable, but as far we know there is no report on its allelopathic activity. To explore allelopathy (as an ecologically sound weed management approach), aqueous methanol extracts of C. grandis were examined for its effect on the seedling growth of cress (Lepidium sativum L.), alfalfa (Medicago sativa L.), rapeseed (Brassica napus L.), lettuce (Lactuca sativa L.), barnyard grass (Echinochloa crus-galli L.), timothy (Phleum pretense L.), foxtail fescue (Vulpia myuros (L.) C. C. Gmel.), and Italian ryegrass (Lolium multiflorum Lam.) at six concentrations (1, 3, 10, 30, 100 and 300 mg dry weight equivalent extract/ml). The growth inhibitory effect of the extracts on the test plant species varied and depended on extract concentration. The concentrations required for 50% growth inhibition of the shoots and roots of the test plant species were 6.3–220.8 and 4.8–80.9 mg dry weight equivalent extract/ml of C. grandis, respectively. The lettuce seedlings were most sensitive to the extracts, whereas the barnyard grass seedlings were least sensitive. These results suggest that C. grandis may have allelopathic potential and might be useful in developing a bio-herbicide in an eco-friendly management system.