Allelopathic Effects of Extracts of Trifolium repens on the Seed Germination and Seedling Growth of Zoysia japonica

The allelopathic effects of aqueous extracts from Trifolium repens were studied. Aqueous extracts of leaves, stems, roots and flowers of T. repens strongly inhibited the seed germination and seedling growth of Zoysia japonica. In general, the higher concentration of the extracts showed the more great inhibition effect. The phenolic compounds extracted from T repens were analysed and identified using gas chromatography. 14 phenolic compounds were isolated from the leaves, stems, roots and flowers: caffeic acid, p-hydroxy benzoic acid, ferulic acid, gallic acid, p-coumaric acid, vanillic acid, trans-cinnamic acid, 2,5 dihydroxy benzoic acid, syringic acid, 2-hydroxy cinnamic acid, benzoic acid, salicylic acid, phloroglucinol and phanylacetic acid. The seed germination and relative growth ratio of Z. japonica by 14 phenolic compounds were inhibited in whole treatment. Stronger growth inhibitor were benzoic acid, salicylic acid and trans-cinnamic acid. From these results it is suggested that the phenolic compounds from T. repens seemed to be responsible for the allelopathic potential.