摘要 : The allelopathic effects of rice weeds, namely <i>Echinochloa crus-galli, Cyperus difformis, Paspalum paspalodes</i> [<i>P. distichum</i>] and <i>Sagittaria trifolia</i>, of north Iran were evaluated against seeds of rice cv. Taro... 展开 The allelopathic effects of rice weeds, namely <i>Echinochloa crus-galli, Cyperus difformis, Paspalum paspalodes</i> [<i>P. distichum</i>] and <i>Sagittaria trifolia</i>, of north Iran were evaluated against seeds of rice cv. Tarom in 2008. Roots, stems and leaves of each weed were collected from different paddy fields after maturity. The seedling growth (radicle and hypocotyl length) and seed germination of Tarom were inhibited significantly by the leachates of the weed species. There were also differences in allelopathic potential among the different parts of the weeds. The stem leachates of <i>S. trifolia</i> (68.50%) had the highest inhibitory effect on the test crop. High performance thin layer chromatography revealed the presence of terpenoids, coumarins and phenolic compounds in the roots, stems and leaves of the weeds. The leaf of <i>P. paspalodes</i> had the highest coumarin content, while the root of <i>C. difformis</i> contained the highest amount of phenolic compounds. Terpenoid content was higher in roots and stems compared to leaves of the weeds. 收起