محمدحسین راشد محصل

An experiment was conducted for evaluation the allelopathic potential of extract soybean shoot on seed germination and seedling growth of four weed species tumble pigweed, smooth pigweed, common lambsqurters and black nightshade. For each species a factorial experiment was used in a completely randomized design with three replications. Plant shoots were gathered in flowering stage and individually dried and then ground. Water extracts with concentrations of 5, 10, 20 and 40 % were prepared and distilled water was used as control. Seeds of weed sat in petri dishes. Then, their germination percentage determined after 11 days. The results showed that root length, germination rate and percentage reduced in weed species when concentration rate was increased. Black nightshade had most germination percentage (88.14), root length (46.4 mm) and germination uniformity (1.5 days). Therefore, it affected with soybean shoot extract less than other weed species. Tumble pigweed had most germination rate (3 days) and its required time to achieved 10, 50 and 90% maximum germination, was about 2, 2.5 and 4 days respectively. Therefore, It was better than other species. Most inhibition effect of extracts on germination percentage belonged to smooth pigweed.