Plant biostimulating effects of seaweed extracts explained by their plant hormone activities supported the idea to screen the hormone content of microalgae and study their biostimulating activities. Results obtained with bioassays and analytical methods confirmed that all microalgae produced plant hormones. However, hormone-like activities of sewage-grown microalgae was possible only with special bioassays. Wheat, maize and rapeseed field experiments verified the biostimulating effects of fast-growing microalgae.
