LAUSR

The toxic effects of lead (10 and 50 μM) in the nutrient solution and distilled water on Scots pine (Pinus sylvestris L.) seedlings were studied. It was shown that due to the rapid lead immobilization by the components of the nutrient solution, its measured concentrations were tens of times lower than the nominal ones already after 15 minutes after addition. The pronounced toxic Pb effects were manifested only on seedlings exposed to lead in distilled water, since the availability and stability of lead in such conditions were significantly higher and lasted longer than in the nutrient solution. The most pronounced toxic Pb effect was manifested in a decrease in the physiological activity of root cells and an increase in their oxidative status due to the accumulation of MDA and 4-hydroxyalkenals. Against this background, a decrease in the content of gallic acid equivalents, catechins and proanthocyanidins was noted in the roots of seedlings, while the contents of catechins and proanthocyanidins in the needles doubled. Lead exposure was also accompanied by large-scale imbalances in the contents of mineral nutrients (magnesium, calcium, potassium, iron, zinc and copper) in seedlings. It has been shown that Scots pine seedlings accumulate about 0.15 μmol/g of Pb in needles without showing any visible damage, with 0.8 μM of available lead in the nutrient solution.