Abstract: In order to understand the mechanism of the allelopathic effect, some physiological characteristics of Italian ryegrass treated by the aqueous extracts of alfalfa (Medicago sativa L. ‘Alfaking’), hairy vetch (Vicia villosa Roth.), yellow sweetclover (Melilotus officinalis Desr.), white clover (Trifolium repens L. ‘Haifa’), red clover (Trifolium pratense L.) and alsike clover (Trifolium hybridum L.) were investigated during the seed germination and seedling growth stage. Results showed that the amylase activity and seed vigor of Italian ryegrass were both significantly lowered by the aqueous extracts of the legumes (P<0.05). The seed vigor of Italian ryegrass treated by the aqueous extracts of yellow sweetclover was the lowest and 67.8% lower than control. It was also found that the concentrations of soluble sugar and chlorophyll in Italian ryegrass seedling were significantly reduced by the allelochemicals extracted from tested legumes (P<0.05). The activities of superoxide dismutase and peroxidases in Italian ryegrass seedling were changed greatly by the allelochemicals. In addition, the concentration of malondialdehyde in Italian ryegrass seedling treated by the aqueous extracts was significantly higher than that in control (P<0.05). The peroxidase activities of Italian ryegrass seedling treated by the aqueous extracts of alsike clover were the highest and 110.6% higher than control. The allelopathic inhibition effects of the aqueous extracts on the seed germination and seedling growth of Italian ryegrass were mainly caused by lowering the decomposition and supply efficiency of nutrient in the endosperm. The results also indicated that the cytomembranes of Italian ryegrass seedling were damaged by the allelochemicals extracted from tested legumes.

Key words: Legumes, Allelopathy, Italian ryegrass, Nutrient, Membrane damage

摘要： 为探明豆科牧草化感物质对多花黑麦草（Lolium multifolorum）种子萌发和幼苗生长的化感抑制机理，测定了紫花苜蓿（Medicago sativa L. ‘Alfaking’）、毛苕子（Vicia villosa Roth.）、黄花草木樨（Melilotus officinalis Desr.）、白三叶（Trifolium repens L. ‘Haifa’）、红三叶（Trifolium pratense L.）和杂三叶（Trifolium hybridum L.）这6种豆科牧草水浸提液对多花黑麦草种子萌发及幼苗生长过程中主要生理生化指标的影响。结果表明：供试豆科牧草水浸提液显著降低多花黑麦草种子的淀粉酶活性和种子活力（P<0.05），黄花草木樨处理组种子活力最低，比对照低67.8%；各处理组可显著降低多花黑麦草幼苗的可溶性糖和叶绿素含量（P<0.05）；显著提高多花黑麦草幼苗体内超氧化物歧化酶、过氧化物酶的活性以及丙二醛含量（P<0.05），杂三叶处理组过氧化物酶活性达最高，比对照高110.6%。豆科牧草的化感物质可能主要通过抑制多花黑麦草种子胚乳养分的分解和供应来抑制种子萌发及幼苗生长，豆科牧草的化感物质对多花黑麦草幼苗细胞膜亦有一定的损伤作用。

关键词: 豆科牧草, 化感作用, 多花黑麦草, 营养, 膜损伤