Changes in the structural indices of annual shoots of Quercus rubra under anthropogenic impact

Abstract

Air pollution is one of the important problems of large cities. In connection with this, comprehensive study of the mechanisms of the corresponding reactions of tree species, introduced in the process of landscaping, to various environmental factors is required. The aim of this study is to analyze the influence of urban technogenic environmental pollution on the anatomical characteristics of Quercus rubra Linnaeus, 1753 annual shoots. The object of research was 35-year-old plants of Q. rubra, which grew in a non-polluted site (conditionally clean zone), the Botanical Garden of DNU (plot 1) and in a polluted site (roadside planting) (plot 2) of Dnipro City. Industrial emissions of the city's western, northeastern and northwest industrial complexes also have an effect on plants, depending on the wind direction. For anatomical research, the annual shoots were taken at the tips of the vegetation from the south-eastern side of the model trees at a height of 2 m and fixed in 70% alcohol. Cross sections were made at a distance of 1 cm from the beginning of growth. Phloroglucine was used to dye the cells. The influence of industrial and automobile emissions on the structural parameters of Q. rubra shoots was investigated. We established that the membrane thickened evenly in both control and experimental plants. Cork thickness of Q. rubra shoots, growing in the roadside plantation was higher than in plants of the Botanical Garden by 57.5%. Increasing its thickness in plants exposed to atmospheric air pollution has an adaptive value. Q. rubra shoots have a tabulate type of collenchyma, the tangent walls of whose cells thicken. The collenchyma cells of the control variant of shoots are larger. This tissue was thicker in Q. rubra shoots from the polluted site by 26.8% compared to those from the non-polluted zone. The parenchyma cells of the primary cortex were large and contained chloroplasts. The thickness of this histological element on the shoot circumference varied considerably both in the control and experimental variants, which is the result of its uneven formation. This is due to the fact that the shape of the shoot core resembles a pentagonal star, and the layers of phloem and xylem tissues repeat its shape. The thickness of each of them in the cross section of the shoots in various places varied little, while the parenchyma of the primary cortex above the ray cells was narrower, and between them was broader, as a result the thickness of the shoots was aligned in a circle. In areas where the parenchyma of the primary cortex was narrower, it was better developed in the shoots of experimental plants than the control ones, but where its layer was thicker, it was more developed in plants of the control variant. The diameter of the primary cortex in the shoots of the experimental variant in its narrower parts was 120.5% of the control, and in the broader -87.6%, which is due to unequal changes in the thickness of the primary cortex parenchyma, possibly with different rates of cell division. In the one-year Q. rubra shoots...

The state of bio-ecological characteristics of the one-year shoots of Robinia pseudoacacia L. Under the conditions of industrial pollution

“…The previous research showed that moderate doses of toxic substances stimulate the thickening of cork parenchyma more intensively in R. centifolia and R. rugosa, whereas severe contamination inhibits the development of this tissue. Bessonova and Kryvoruchko (2017) showed that in the shoots of Quercus rubra L. plants growing in roadside plantation, there was an increase of the cork and collenchyma thickness indices, 4 radial rows of cells in the reference area, 6 rows in the test area, which according to the authors, ensures better protection of internal tissues from the penetration of pollutants.…”

БІОІНДИКАЦІЇ СТАНУ ЕДАФОТОПУ ЗА ПОКАЗНИКАМИ АКУМУЛЯЦІЇ ВАЖКИХ МЕТАЛІВ ВЕГЕТАЦІЙНИМИ ОРГАНАМИ (на прикладі Тaraxacum officinale Wigg.)

“…Саме тому використання розповсюджених видiв урбанофлори в бiоiндикацiї дозволяє оцiнювати рiвень забруднення промислових агломерацiй. Аналiз наукової лiтератури свiдчить, що iндикаторними видами техногенного забруднення можуть слугувати сiльськогосподарськi культури [10,16,26]; деревнi рослини [5,7,22,28]; трав'янистi види [5,14,33].…”