Comprehensive Analysis of Biochemical Adaptations of Balsamic Poplar (Populus balsamifera L.) to Technogenic Stress in Sanitary Protective Plantations

A comprehensive study of the biochemical adaptations of balsam poplar (Populus balsamifera L.) growing in sanitary protection plantations of the Sterlitamak Industrial Center (SIC) was conducted. A deterioration in the vital condition of balsam poplar under conditions of industrial pollution was established. An increase in the content of gross forms of heavy metals in the soils of the industrial zone was detected, with maximum concentrations in the surface layer (0–20 cm). It was found that an excess of some heavy metals leads to a decrease in the magnesium content in poplar leaves under SIC conditions. In the zone of the highest concentration of toxicants (2–3 km from sources of petrochemical and chemical pollution), an increase in the level of hydrogen peroxide in the leaves by 41.22% was recorded compared to the conditional control zone (10–15 km from the industrial zone). Industrial emissions from city enterprises stimulated oxidative processes in poplar leaves, manifested by an increase in malondialdehyde content (by 33.73%) compared to the conditional control zone. A decrease in flavonol content and catalase activity, an enzyme in the plant antioxidant system, was demonstrated under SIC conditions. Apparently, under stress, plants utilize catalases, flavonols, and other phenolic compounds to reduce the intensification of lipid peroxidation processes. It was found that under SIC pollution, the decrease in flavonols can be compensated for by an increase in anthocyanins. During the active growing season (June-July), a decrease in chlorophyll content was recorded in the leaves of trees in the industrial zone compared to the control zone. It is concluded that technogenic pollution leads to the accumulation of heavy metals in soils, the development of oxidative stress, and the restructuring of the antioxidant system in poplar leaves. A decrease in chlorophyll content can serve as a diagnostic sign of physiological damage to balsam poplars due to exposure to industrial pollution. The detected biochemical changes represent a complex of adaptive responses by plants to industrial stress.

Populus balsamifera, anthocyanins, catalase, relative vital state, lipid peroxidation, flavonols, chlorophylls