Solidago canadensis L. and S. gigantea Aiton. are highly invasive species which widely spread in Europe and threaten local plant communities. Distribution of natural hybrid of S. canadensis and local species S. virgaurea L., known as S. x niederederi Khek., also expands rapidly. One of reasons why invasive species are so successful is their allelopathic activity.
The aim of this work was to compare allelopathic effect of all Solidago species occurring in Lithuania on germination of Solidago seeds (autotoxicity). Solidago canadensis and S. ×niederederi were used as target species. The aqueous extracts of dried green leaves in six concentrations were used. Total percentage of germination, radicle and hypocotyl length of seedlings were measured and the response ratio to treatment was counted. A factorial ANOVA was used to analyze the effect of each factor. In case of significant interactions, a t-test was used to test differences between mean values of treatments.
The inhibitory effect of Solidago leaf extracts was target species specific. S. canadensis was much more sensible to Solidago leaf extracts than S. ×niederederi (F=68.85, p<0.001). The inhibitory potential of all four tested Solidago species did not differ statistically (F=1.40, p=0.251). Therefore, stronger allelopathic effect in nature could be achieved only by higher biomass of invasive species.