Leaf water extracts from invasive Acer negundo do not inhibit seed germination more than leaf extracts from native species

This study was undertaken to test the hypothesis about the allelopathic activity of the alien (invasive) tree species Acer negundo in Eurasia compare with native tree species. Research of allelopathic effects of invasive plants is important for its management because of their influence on native communities. Two experiments in Petri dishes were conducted. The effect of water extracts from leaves on the seed germination of herbaceous plants was assessed. Leaves were collected in the summer and autumn season in areas invaded by A. negundo in Yekaterinburg, Russian Federation. Four treatments (invasive A. negundo and native tree species Sorbus aucuparia , Prunus padus , and Salix caprea ) were tested on seeds of three recipient plant species ( Festuca rubra , Sinapis alba , and Trifolium repens ). We found that water extracts from A. negundo leaves weakly inhibit seed germination compared to distilled water. However, the inhibitory effect of A. negundo was no greater than effects of extracts from leaves of native P. padus and S. caprea . Seed germination was most strongly inhibited with extracts from a native shrub S. aucuparia , and the delay in comparison with distilled water was 1–2 days. Therefore, in Petri dishes water extracts from leaves of A. negundo do not inhibit seed germination of test plants more than native tree species. Our data do not support a hypothesis that allelopathy can explain the ability of A. negundo to influence native communities.