Phytoncidal activity of the needles of Juniperus L. representatives in the technogenic conditions of the city of Dnipro

Abstract

The territory of the Dnipro urban agglomeration is one of the most polluted in Ukraine. The high concentration of industrial enterprises, roads, density of residential buildings and urban population are factors of anthropogenic pressure on urban ecosystems that significantly affect the quality of the habitat of living organisms and human life. Therefore, an urgent problem of modern urban planning and urban amenities is compliance with sanitary requirements for landscaping residential and industrial areas. The creation of decorative compositions with a predominance of tree and shrub species ensures the landscape attractiveness of the city, reduces the level of noise and dust pollution, improves temperature and wind conditions, improves public health by normalizing the psychological state of people and purifying the city air with phytoncides of plants, especially conifers. Taking into account the high decorative qualities and resistance of junipers to adverse climatic conditions, the aim of the study was to analyze the annual dynamics of phytoncidal activity of Juniperus media V. D. Dmitriev «Blue gold» and J. sabina L. «Tamariscifolia» needles in conditionally clean and polluted by vehicle emissions areas of Dnipro city. The plant material was collected at 4 monitoring points in Dnipro, 1 was a conditional control, and the other 3 were experimental plots with different levels of vehicle traffic. Needles were sampled at all periods of shoot ontogeny. The phytoncidal activity was determined by the method of «steaming» microbial test cultures with volatile needle secretions on test cultures of Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus sp., Bacillus subtilis, Esherechia coli, Pseudomonas fluorescens, Candida albicans. The results of the study show that the dynamics of phytoncidal activity of J. media and J. sabina needles during the year is the same in plants growing in a conditionally clean area and under the influence of motor vehicle traffic: the amount of released phytoncides increases in spring, during the period of intensive shoot growth, reaches a maximum at the stage of slowing down their growth (in summer), decreases in autumn, with the cessation of growth processes, and is minimal in winter, when there is no shoot growth. It has been shown that in a clean area, needle extracts of both representatives of the genus Juniperus have the greatest inhibitory effect on the growth of S. aureus colonies, and under the influence of vehicle emissions, the phytoncidal activity is highest against S. aureus and S. epidermidis strains. It was found that out of the two studied representatives of the genus Juniperus, J. media has the highest stability of the ability to secrete phytoncides under conditions of motor vehicle traffic load, which we recommend for use in urban landscaping.