The Influence of Heavy Metal Pollution on the Pigment Content in the Assimilation Apparatus of Poplar Cultivars in the Conditions of the Iron Ore Region

Abstract

We carried out studies of the translocation of heavy metals in the soils of Kryvyi Rih. The peculiarities of the accumulation of heavy metals in the assimilation apparatus of seven poplar cultivars were clarified. The maximum rates of translocation of heavy metals were detected at the monitoring site of the industrial site of Northern Iron Ore Dressing Combine (henceforth referred to as Pivnichnyi HZK or PivnHZK). In the leaves of poplars “Lvivska,” “Hradizhzka,” and “I-45/51,” cadmium, one of the highly toxic elements, accumulates 25–30 times more than in the leaves of control plants. High rates of accumulation of heavy metals lead to a violation of the functioning of the plant organism at the physiological and biochemical levels, as evidenced by changes in the content of chlorophyll a and b. The amount of the main pigments of photosynthesis in the leaves of poplar cultivars under conditions of environmental pollution with heavy metals is lower than in the control, which indicates the inclusion of plant signaling mechanisms. At the same time, the amount of carotenoids in the organs of assimilation of poplars growing on the industrial sites of Northern and Central Iron Ore Dressing Combines (henceforth referred to as Central HZK or CHZK) increases and indicates the realization of their protective functions. The investigated cultivars can be divided into two groups according to the intensity of changes in pigment content. The first group (with a decrease in chlorophylls up to 2 times and an increase in the amount of carotenoids up to 2.5 times) includes “I-45/51,” “Lvivska,” and “Hradizhzka,” and the second group (with a decrease in chlorophylls by more than 2 times and an increase in the amount of carotenoids by more than 2.5 times) includes “Keliberdynska,” “Robusta,” “Sacrau-59,” and “Tronco.” This fact indicates better adaptation and greater resistance of cultivars of the first group to the action of heavy metals.