Study on allelopathy of root, stem, and leaf aqueous extracts of different medicago sativa varieties

chinois. 对10个苜蓿（Medicago sativa L．）品种根、茎、叶水提液对受体苜蓿阿尔冈金种子萌发、幼苗生长和幼苗生物量积累进行研究，结果表明：10个苜蓿品种根、茎、叶水提液均对受体苜蓿种子发芽存在抑制作用，且浓度越大，抑制作用越明显；低浓度根水提液促进受体苜蓿根的生长，而高浓度反之，茎、叶水提液抑制受体苜蓿根的生长；根、茎、叶水提液抑制幼苗的生长；在低浓度处理下，大部分品种根、茎水提液对受体苜蓿根的鲜重表现为促进作用，而大部分品种叶的水提液表现为抑制作用，在高浓度下所有品种根、茎、叶水提液均为抑制作用；对于幼苗的鲜重，除0．01％根的水提液部分品种表现为促进作用，大部分品种都为抑制作用。

anglais. It is well known that the biomass productivity of alfalfa （Medicago sativa L. ） decreases gradually after the fifth year of being planted due to the allelopathic impacts and the land has to be cultivated by other crops in rotation. Although there are numerous varieties with different allelopathy, the study on al- lelopathy differences among varieties is scarce. The effects of the aqueous extract of the roots, stems and leaves of ten alfalfa varieties were studied on seed germination and seedling growth of M. sativa L. cv. Algonquin. The results indicate that the extracts from roots, stems and leaves restrained the seed germination with increased intensity along with increased extract concentration. The extracts from roots promoted the root growth at lower concentration but delayed the root growth at higher concentration and the extracts from stems and leaves delayed the root growth. The extracts from roots, stems and leaves inhibited the seedling growth. At lower concentration, the extracts from the roots and stems of most varieties promoted root biomass accumulation, while the extracts from the leaves of most varieties had negative effects. More- over, at higher concentration, all extracts inhibited root biomass accumulation. All the extracts except the 0.01% roots extracts of some varieties inhibited the stem and leaf biomass accumulation.