Abstract: In order to ascertain the biochemical effects of Trifolium repens L. on grasses, the effects of different levels of Trifolium repens root exudates on the root, leaf superoxide dismutase (SOD), peroxidase (POD), and catalase activities (CAT) as well as malondialdehyde (MDA) contents of Lolium perenne, Festuca rubra, Festuca arundinacea, Poa pratensis, Agrostis stolonifera were studied in this paper. Results showed that the root exudates of white clover had concentration effect on the tested indexes of all the acceptors. The root exudates improved the superoxide dismutase and catalase activities of all tested turf grasses at low concentration (0.002 g·mL^-1), whereas inhibited the activities at high concentration (0.05 g·mL^-1) (P<0.05). The peroxidase activities and malondialdehyde contents of all tested acceptors were enhanced, while the root activities declined with the concentration increase of root exudates. These results indicated that white clover root exudates could cause the response of acceptors to stress. Meanwhile the allelochemical effects of root exudates on five tested acceptors were expressed by changing the enzyme activity and lipid peroxidation of seedling.

Key words: Trifolium repens L., Root exudate, Turfgrass, Allelopathy, Biochemical indexes

摘要： 为探讨根系分泌物在白三叶（Trifolium repens L.）入侵禾本科草坪过程中的生化效应，采用水培法收集其根系分泌物，检测不同浓度白三叶根系分泌物对多年生黑麦草（Lolium perenne L.）、紫羊茅（Festuca rubra L.）、高羊茅（Festuca arundinacea Schreb.）、草地早熟禾（Poa pratensis L.）和匍匐翦股颖（Agrostis stolonifera L.）叶片超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）的活性和丙二醛（MDA）含量以及根系活力的影响。结果表明：白三叶根系分泌物对5种草坪草上述生理生化指标均具有浓度效应。在低浓度下（0.002 g·mL^-1）对SOD和CAT活性具有促进效应，在高浓度下（0.05 g·mL^-1）则具有抑制效应。5种受体的POD活性和MDA含量均随白三叶根系分泌物浓度增大而升高，根系活力则随着其浓度增大而降低。因此，白三叶根系分泌物可引起受体植物对逆境的响应，5种草坪草化感效应的生化机制可能是分泌物中化感物质通过改变受体幼苗体内保护酶活性及脂膜过氧化来表现的。

关键词: 白三叶, 根系分泌物, 草坪草, 化感作用, 生化指标