Cogongrass (Imperata cylindrica [L.] Raeusch.) is a perennial rhizomatous grass that belongs to the Poaceae and is widely distributed in tropical, subtropical and temperate regions over the world. The grass is strongly invasive and is suggested to have allelopathic potential. However, limited information is available on allelopathic substances in cogongrass rhizomes. Therefore, the allelopathic potential and substances in cogongrass rhizomes were investigated. The extracts of cogongrass rhizomes inhibited the root and shoot growth of barnyard grass, ryegrass, timothy, cress, lettuce and alfalfa. After bioassay‐guided separations of the extracts, four growth inhibitory substances, 5‐methoxyflavone, 5,2′‐dimethoxyflavone, methyl caffeate and abscisic acid, were isolated. 5‐Methoxyflavone, 5,2′‐dimethoxyflavone and methyl caffeate significantly inhibited the root and shoot growth of cress at concentrations of ≥0.03–0.3 m mol L⁻¹ and their concentrations required for 50% growth inhibition were 0.079–0.24, 0.23–1.1 and 0.59–0.88 m mol L⁻¹, respectively. The other isolated substance, abscisic acid, has been reported to have strong growth inhibitory activity. Its concentrations required for 50% growth inhibition on cress were 0.31–0.61 μ mol L⁻¹. The present study suggests that cogongrass rhizomes might have allelopathic potential and that those four substances might contribute to that potential.

中文翻译：

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香茅根茎的植物生长抑制活性及具有化感作用的活性物质

香茅（Imperata cylindrica[L.] Raeusch。）是多年生根茎草，属于禾本科，广泛分布于世界各地的热带，亚热带和温带地区。草具有很强的侵入性，建议具有化感作用。但是，关于禾本科植物根茎中的化感物质的信息很少。因此，研究了香茅根茎中的化感作用潜力和物质。茅草根茎的提取物抑制of草，黑麦草，提摩西，水芹，生菜和苜蓿的根和芽生长。在提取物的生物测定指导下，分离出四种生长抑制物质5-甲氧基黄酮，5,2'-二甲氧基黄酮，咖啡酸甲酯和脱落酸。5-甲氧基黄酮，5，^-1及其抑制50％生长所需的浓度分别为0.079-0.24、0.23-1.1和0.59-0.88 m mol L ^-1。据报道，另一种分离的物质脱落酸具有很强的生长抑制活性。水芹对50％生长抑制所需的浓度为0.31-0.61μmol L ^-1。目前的研究表明，禾本科植物的根茎可能具有化感作用的潜力，而这四种物质可能有助于这种潜力。