Abstract:The effects of extracts from root of Rheum tanguticum on seed germination and seedling growth of Triticum aestivum and Elymus nutans were determined. The main results were as follows: Strong allelopathic effects of the aqueous extracts were observed. Higher concentration of the aqueous extracts could inhibit the seed germination and seedling growth of T. aestivum and E. nutans, while lower concentration of the aqueous extracts could accelerate seedling growth of T. aestivum. The crude anthraquinone extracts only inhibited the seedling growth of E. nutans and the inhibiting effects became stronger with the increased concentration. The crude polysaccharide extracts inhibited the root growth of T. aestivum and E. nutans, and high concentrations of polysaccharide extracts prolonged seed germination of E. nutans.