Fetsiukh A. Physiological Aspects of Salix viminalis L. Tolerance to Technogenic Pollution Conditions

The relevance of the Ph.D. thesis lies in the global problem of technogenic environmental pollution and the search for safe ways to restore it in modern conditions. Adaptive reactions of energy plants, namely basket willow (Salix viminalis L.), under growing conditions on the territory of the Stebnyk tailing, which contains 22 million tons of salt-clay waste from flotation enrichment was investigated by the author. The processes of the formation of physiological adaptive reactions of S. viminalis, antioxidant system and proteins in plant organs, the composition of endophytic bacteria of the roots, as well as the phytoremediation properties of willow under the technogenically polluted substrate on the Stebnyk tailing was comprehensively investigated. Willow plants were stressed in the conditions of growth on a technogenically polluted substrate and showed adaptive reactions. Slight suppression of the growth parameters of S. viminalis during growth on Stebnytsk tailing substrate was revealed both under the laboratory and field conditions. The doctoral candidate determined the integral indicator of the growth stability of S. viminalis. A significant decrease in the zinc content in the experimental substrate of the tailing, compared to the initial content before growing willow plants was established. The author evaluated the ecological informativeness of the content of the HM by ecological-geochemical coefficients. The highest concentration coefficient was for cadmium, which significantly exceeded the average content of the element in arable lands of Ukraine, and molybdenum. Studies of the biogeochemical activity of plants have confirmed that willow plants have a high ability to accumulate heavy metals from the substrate of the Stebnyk tailing. The screening of S. viminalis root bacteria under exposure to rhizospheric bacteria Salicornia europaea L. and technogenically polluted substrate of the Stebnyk tailing was performed. The positive effect of rhizospheric bacteria of S. europaea on increasing the relative number of bacteria in the samples was emphasizes. The genera Marinobacterium, Idiomarina, Marinamicrobium, and Halomonas were identified, which were represented in the samples from the most polluted areas of the tailing. The author noted the presence of ACC (1-aminocyclopropane-1-carboxylic acid)-utilizing bacteria of the precursor of "stress" ethylene. Changes in ACC concentration were more visible under the conditions of S. europeae rhizobacteria treatment. The accumulation of proteins in the stems and roots of 30-day-old S. viminalis during growth on the polluted substrate of the tailing under laboratory conditions was revealed. Qualitative and quantitative differences in the spectra of low-molecular-weight proteins were observed in the control and experimental variants. The protein changes were more visible in the organs of the experimental S. viminalis. The effect of technogenic pollution on the antioxidant system of 30-day-old S. viminalis, which was shown in a decrease in the content of phenolic compounds and in an increase in the content of AsA, DHA, and DKG in the leaves and roots of S. viminalis in comparison to control plants was established. The obtained results may indicate the adaptation of S. viminalis plants to the influence of technogenic pollution of the Stebnyk tailing. Enzymatic activity of 30-day-old S. viminalis was the highest in the leaves of the experimental plants, compared to the control. An increase in total peroxidase activity is observed in plants growing on a contaminated substrate. The accumulation of proline in the stems and roots of the 30-day-old S. viminalis experimental variant compared to the control was established. The author explains the results of the study by physiological drought, which occurs as a result of the salinization of the tailing substrate. As a result of conducted field experiment, the author notes the activity of peroxidase and the accumulation of proline in the stems of willow plants under conditions of technogenic pollution. However, an increase in catalase activity was found in the roots. The adaptation mechanisms of S. viminalis were shown in an increase in the amount of alcohol- and water-soluble sugars in the leaves and roots of plants. The increase in the number and changes in the activity of enzymes showed the participation of the antioxidant system in the adaptation of S. viminalis to technogenic pollution under the conditions of the Stebnyk tailing. The author noted that S. viminalis showed phytoremediation properties. The obtained data of the doctoral candidate is a starting point for understanding the mechanisms of S. viminalis adaptation to the complex influence of salinity and heavy metals under the conditions of technogenic pollution on the Stebnyk tailing.