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Preliminary Study for the Allelopathic Effect of Water Extracts from Solidago canadensis Leaves

The allelopathy of the exotic invasive plant, Solidago canadensis L. was studied. S. canadensis leaves were extracted with water and partitioned against ethyl acetate and n-butanol sequentially. The two organic fractions, original water extract and the residual water after the organic solvent extraction were tested for inhibitory activity on seed germination and seedling growth of wheat (Triticum aestivum), setaria (Setaria viridis) and its own species. Germination rate, vigor and index were recorded as germination parameters, and radicle and plumule growth and fresh weight of seedlings were recorded as seedling growth parameters. Results showed that the water extracts of S. Canadensis leaves had significant impacts on the seed germination and seedling growth of the three tested plants. n-Butanol fraction showed the strongest allelopathic effect, while the residual water after the organic solvent extraction had no significant phytotoxic effect compared with the control. n-Butanol fraction at 0.5 mg•ml-1 could significantly inhibited the seed germination of the same species, and that at 5 mg•ml-1 could significantly inhibited the seedling growth of the same species. n-Butanol fraction at 1.5 mg•ml-1 could significantly inhibited the seed germination and seedling growth of wheat. n-Butanol fraction at 5 mg•ml-1 could significantly inhibited the seed germination and seedling growth of setaria. The allelochemicals were mainly contained in n-butanol fraction of water extracts from S. canadensis leaves.