Allelopathic effect of aqueous extract of dried olive leaves (Olea europaea L.) on the germination and growth of barley (Hordeum vulgare L.) and associated weeds

Abstract

This study was conducted during the 2022–2023 growing season to evaluate the allelopathic effects of the aqueous extract of dried olive (Olea europaea L.) leaf powder on the germination and early growth of barley (Hordeum vulgare L.) and selected associated weeds. A laboratory experiment was performed using four extract concentrations (0, 10, 20, and 30%), and their effects on germination percentage, radicle length, and plumule length were assessed. The experiment included two barley cultivars (Wadi Otba and Eraoun) and two weed species, Emex spinosa L. and Avena fatua L., arranged in a completely randomized design with three replications.

The results revealed a concentration-dependent allelopathic response. Low extract concentration (10%) stimulated germination and seedling growth of barley cultivars, whereas higher concentrations (20% and 30%) caused significant inhibitory effects on both barley and weed species. The strongest inhibitory effect was observed on Emex spinosa, where germination was completely suppressed at the highest concentration. These findings demonstrate that olive leaf aqueous extract possesses potent allelopathic activity and may serve as an environmentally friendly alternative for weed management within sustainable agricultural systems.