Allelopathic Potential and Mechanism of Rosebay Willowherb [Chamaenerion angustifolium (L.) Scop.] Demonstrated on Model Plant Lettuce

Allelopathic plants are important resources for the discovery of bioherbicides. Rosebay willowherb [Chamaenerion angustifolium (L.) Scop. syn. Epilobium angustifolium L.] widely distributes in Western Asia, Europe, and NorthAmerica, and behaves as a dominant species within the community due to theproduction of substances that restrict growth of other plants. This study aims atinvestigating the allelopathic potential of rosebay willowherb by evaluation ofthe effects of aqueous extracts from different parts on seed germination and seedlinggrowth in lettuce (Lactuca sativa L.), as well as measuring the accumulation ofreactive oxygen species and structural analysis of root tips via scanning electronand transmission electron microscopy. It was observed that the aqueous extractsfrom the leaves of rosebay willowherb had the strongest inhibitory effect on the germination index, germination energy and total germination of lettuce seeds, followedby capsular fruits and flowers, and the inhibition effect of stems was the weakest.All aqueous extracts (100 mg/mL) showed a significant inhibitory effect on radicleelongation of lettuce seedlings. Additionally, after treatment with the aqueousextract of rosebay willowherb leaves, accumulation of reactive oxygen speciesincreased in columella cells, which correlated with disruption of root tip structure.