Abstract:Wild rice,Oryza rufipogon,is the presumed ancestor of Asian cultivated rice,O.sativa,and is the most important genetic resource for rice improvement.Aqueous leachates of leaf,stem,and root parts of Sagittaria trifolia and O.rufipogon were made to determine the effects on their seed germination and seedling growth.All aqueous leachates significantly promoted seed germination of S.trifolia and O.rufipogon when compared with distilled water control.The seed germination of O.rufipogon significantly increased from 25% under control to 39%-54% with the application of aqueous leachates of leaf of S.trifolia,and leaf,stem and root plant part of O.rufipogon,respectively.The seed germination of S.trifolia significantly increased from 0 under control to 9%-81% with the application of aqueous leaf,stem and root leachates of S.trifolia and O.rufipogon,respectively.Aqueous leachates of all plant parts had a strong promotion effect on shoot elongation of both species seedlings.The leaf leachates of O.rufipogon,and leaf,stem and root of S.trifolia had a strong inhibitory effect on root elongation of both species seedlings,while the stem and root leachates of O.rufipogon had a strong promotion effect on root elongation of S.trifolia.It was apparent that S.trifolia was more susceptive to allelopathic effects than O.rufipogon.Seedling root length may be the strongest morphological trait for allelopathic assessment of wetland plants.The results from this study suggest that allelopathy may play an important role in protection of endangered species.