Abstract
Cu is a microelement that plays an exclusively catalytic role in plants in numerous enzymes and acts in nitrite reduction as a component of nitrite-reductase. Copper compounds are used in agriculture against a large number of parasitic fungi so that very high concentrations of Cu can be found in the aerial parts of plants and in the soil. The effects of repeated spraying with copper oxychloride solution on the development and active principle content of Datura metel L. were studied.