Effect of the Extract from the Soil around the Alfalfa Roots on Three Species of Plant Seed Germination and Seedling Growth

[Objective] The ability of the allelopathy of the different concentrations of extracts from the soil around the alfalfa roots with 15 year-old and 4 year-old and its effect on following crop growth were researched.[Method] The Medicago sativa L.,Panicum miliaceum L.and Avena nuda L.seeds were cultured on the paper containing the different concentrations of extracts.[Results] There was not efficiency of the extracts from the soil around the Medicago sativa L.roots on seed germination of Panicum miliaceum L.,but the significant inhibition efficiency on Avena nuda L.and Medicago sativa L.seed germination.The inhibition intensive to seed germination was Avena nuda L. Medicago sativa L.,and the higher the concentration was,the stronger the inhibiting ability was.The inhibition ability of the extract from the soil around the Medicago sativa L.roots with 15 year-old was higher than 4 year-old to seed germination.There was not efficiency of the extracts on the root length and plant height of Panicum miliaceum L.but the significant inhibition efficiency on the root growth of Medicago sativa L.The extract from the soil around the Medicago sativa L.roots with 4 year-old could promote the growth of the root and aerial parts of Avena nuda L.and the higher the concentration was,the more the promoting role was.[Conclusion] The ability of the allelopathy of the extracts from the soil around the Medicago sativa L.roots with 15 year-old is higher than 4 year-old,which had the inhibition to Avena nuda L.and Medicago sativa L..The extract from the soil around the Medicago sativa L.roots with 4 year-old could promote the seedling growth of Avena nuda L.It was recommended that the Avena nuda L.be grown after the alfalfa harvesting.