中文摘要：

以化感水稻PI312777和非化感水稻Lemont与稗草在自然条件下土壤共培种植产生的抑草圈现象为研究对象,采用土壤三明治法测定了12 cm有效抑草圈处稗草根际土壤以及经水和70％（体积分数）乙醇提取后的土壤对稗草的抑制作用,以及提取物的生物活性.结果表明：与对照相比,化感水稻PI312777抑制圈土壤显著抑制受体稗草根的生长,而该土壤中水和70％（体积分数）乙醇提取物对莴苣的抑制率分别为42.6％和21.4％.表明水稻有效抑草圈的土壤中含有水溶性和醇溶性化感物质,以水为溶剂提取水稻有效抑草圈土壤物质的效率更高.

英文摘要：

The allelopathic potentials of different allelopathic rice accessions were evaluated by the method of weed inhibitory circle.The rhizosphere soils of barnyardgrass at 12 cm distance from rice seedlings,the effective inhibition distance on target weed,were sampled to explore the inhibitory effect.The effects of rhizosphere soils and the soils extracted by water and 70％ aqueous ethanol on bamyardgrass were determined by rhizosphere soil method.The bioactivities of the extracts on lettuce were simultaneously determined.The results showed that the soils at the effective inhibition distance had significant inhibitory effect on the root length of bamyardgrass.The inhibitory rates of water extracts and ethanol extracts on root length of lettuce were 42.6％ and 21.4％,respectively.These results indicated that the soils at the effective inhibition distance contained both water-soluble and ethanol-soluble compounds.Water was more effective solvent for the extraction of allelochemicals from paddy soils.