Allelopathic effects from aqueous extracts of exotic Thalia dealbata on six aquatic plant species

Key words: 
• botany /
• Thalia dealbata /
• allelopathy /
• aquatic plant /
• aqueous extract /
• seed germination

Abstract: To test the allelopathic effects of Thalia dealbata on seed germination and seedling growth，aqueous extracts of the T. dealbata rhizome and root were applied to six aquatic plants；namely，Nymphoides peltatum，Vallisneria natans，Nasturtium officinale，Iris pseudacorus，Phragmites australis，and Polygonum hydropiper using the bioassay method. Results showed that the aquatic rhizome and root extracts at a concentration of 50 gL-1 had highly significant （P ＜ 0.01） allelopathic effects on seed germination for all six aquatic plant species. Seedling shoot length for the six listed species above were reduced 29.2%，64.9%，42.3%，87.1%，18.2%，and 75.6%，respectively；and seedling root length was reduced 50.5%，90.1%，72.7%，76.2%，29.9%，and 74.2%，in that order. Also the seed germination index was more sensitive to extract application than germination percentage and other indexes with allelopathic sensitivity in the order of Polygonum hydropiper ＞ Nasturtium officinale ＞ V. natans ＞ I. pseudacorus ＞ Nymphoides peltata ＞ Phragmites australis.［Ch，３ fig. 1 tab. 26 ref.］