Allelopathic property and an allelopathic substance in Eleocharis atropurpurea (Retz.)

Plants, which include crops, weeds, and trees, are able to release effective allelochemicals that inhibit the growth and development of other plants. Eleocharis atropurpurea, a small, annual tufted weed, is renowned for being widely found in crop fields, yet there have been no studies on the allelopathy of E. atropurpurea (Cyperaceae). Thus, we explored the allelopathic potential and allelochemicals in E. atropurpurea and found that aqueous methanol extracts of E. atropurpurea inhibited the seedling growth of Lepidium sativum, Medicago sativa, Lolium multiflorum, and Phleum pratense. There was a significant negative correlation between the seedling growth of the test plants and extract concentration. Extracts were purified using several chromatographic steps and one growth inhibitory substance was isolated and identified by spectroscopic analysis as trans-ferulaldehyde. The active substance trans-ferulaldehyde significantly inhibited the shoot and root length of Lepidium sativum at concentrations higher than 1.0 and 3.0 mM, respectively, whereas the seedling length of Echinochloa crus-galli was inhibited by trans-ferulaldehyde at concentrations higher than 3.0 mM. The trans-ferulaldehyde I₅₀ values for the growth of Lepidium sativum and Echinochloa crus-galli were in the range of 0.73–3.68 mM. The growth inhibitory results of this study suggest that trans-ferulaldehyde may be responsible for the inhibitory effects of E. atropurpurea and may contribute to weed allelopathy.