Allelopathic effect of aqueous extracts of Canadian goldenrod on germination and growth of radish

In this study we tested the effects of Solidago canadensis extracts on seed germination and early growth of radish (Raphanus sativus). The aqueous extracts of 2.5% (m/v) concentration were prepared from roots, rhizomes, stems, leaves and inflorescences and applied onto the filter paper in Petri dishes where radish seeds were sown. We determined the germination rate and seedling growth for four days. The extracts from leaves and inflorescences delayed germination, whereas extracts from stems and roots had no significant effect on seed germination. The extracts from rhizome had a slightly stimulatory effect on the seed germination and promoted shoot length of radish seedlings, while extracts from leaves inhibited root and shoot length and seedlings development.