Heavy metals in plants were prepared for analyzing by dry combustion
at 450 °C, the rest was dissolved by an acid mixture (HNO3+HCl)
(Methodological Guidelines on the Determination of Heavy Metals in
Agricultural Soils and Crops, 1992). The content of heavy metals in extracts
from plants was determined by atomic absorption spectrophotometry
(Scientific Buck 200 A). The nitrogen content in grain of
barley was analyzed by the optical method with indophenol greens
(Mineev, 1989).