||Contamination by arsenic (As) and antimony (Sb) is not only a serious environmental problem in highly-industrialized countries of the world, however also in Slovakia, mainly due to mining and power industry. The sites contaminated by these elements can be found across the whole Slovakia, from Malé Karpaty Mountains, Horná Nitra region, Liptov region to surrounding of Košice city in east Slovakia. As and Sb belong to toxic and dangerous elements for all living organisms. Despite an intensive research in the last years there is still only limited knowledge about the effect and phytotoxicity of As and Sb, and especially on interaction of toxic (As, Sb) and beneficial (Si) metalloids in plants what is the research aspect of this project. Therefore, the main aim of this project is to obtain a complex characterization of beneficial effects of Si on toxicity of individual elements and their combination on molecular-biological, biochemical, anatomical-morphological and physiological level. As a model object, important agricultural crops will be investigated.