EN
The objective of this research was to determine if copper concentration in the top plant tissue can be a reliable indicator of Cu toxicity. A four-year microplots experiment was carried out with 4 copper treatments: 0, 30, 60, and 90 kg ha 1. Spring wheat, red clover, and maize were grown on the microplots filled with sandy acid soil. In the first and second year, after application of the highest Cu rate, wheat and clover yields dramatically decreased. In spite of the fact that the yield decreases were very deep, the Cu tissue concentrations didn't reflect them; there never was an excessive Cu accumulation in top plants. This study and inspection of the published researches reveal that the Cu concentration in plant top tissue or in grain is not a sensitive or reliable indicator of Cu phytotoxicity, and it carries a possibility of misleading assessment.