Phytotoxicity tests were performed on the following higher plants: great duckweed (Spirodela polyrhiza (L) Schleid.), garden cress (Lepidium sativum L.), and spiderwort (Tradescantia). Toxic and genotoxic effects of water and foam of the Ignalina NPP heated water canal that are characterised by high concentration of various contaminates, including heavy metals, were investigated applying the model mixtures prepared basing on the concentrations of heavy metals found in the water of heated canal in 1996. It was established that the stamen-hair system of spiderwort was the most sensitive to model and natural mixtures of heavy metals. The great duckweed was less sensitive to the impact of mixtures of heavy metals, and garden cress was the least sensitive of the tested plants. Investigation of the phytotoxicity of model and natural mixtures of heavy metals showed that spiderwort, great duckweed, and garden cress are sufficiently sensitive and useful as a complex of test-organisms. This complex indicates the level of the phytotoxicity of the investigated water samples, and moreover, it allows to clarify the physiological a1d genetic aspects of the effects induced by heavy metals.
Keywords: phytotoxicity, heavy metals, Tradescantia, Spirodela polyrhiza, Lepidium sativum.