Bioecological analysis of Picea pungens needles in the deterioral conditions of the DTEK Prydniprovsk thermal power plant

Abstract

Crucial for the research on adaptiogenesis of introduced coniferous species is the study the anatomical structure of their vegetative organs, especially the needles, which provides the productivity of individual trees and plantings in general. In conditions of anthropogenic pressure of the environment there are changes in the thickness and structure of the histological elements of vegetative organs of coniferous species, in the first place, protective tissues. Therefore, the study of the anatomical structure of the needles is relevant in the context of studying the ways and mechanisms of adaptation of gymnosperms to industrial emissions and the finding sensitive phytoindicators of environmental pollution and the condition of coniferous plants in man-made zones. However, today the chronic effect of phytotoxicants on the anatomical structure of needles is insufficiently studied. Ecological and anatomical studies of P. pungens in the conditions of the steppe zone of Ukraine for the effects of technogenesis are practically absent. Prydniprovsk TPP is the largest source of pollution in the city of Dnipro (Ukraine): its emissions make up 68,9 % of the volume of toxic compounds of all enterprises and transport facilities. The main pollutants of emissions from Prydniprovsk TPP are SO2, NO2, solids, CO. In order to reduce the negative impact of the TPP emissions, green plantations mainly from softwood are created around it, which purify the atmosphere and improve the environment throughout the year. In view of this, the purpose of the work is to analyse the state of morphological and anatomical indices of the Picea pungens Engelm f. glauca Beissn. needles under the influence of emissions from Prydniprovsk TPP. The research is conducted according to generally accepted methods (Zlobin et al., 2009; Albrechtova, 2003; Permjakov, 1988). It has been found that the length and weight of needles in experimental specimens of P. pungens decrease with respect to the values of these indices in plants of relatively pure zone; therefore, they are sensitive growth parameters to the action of environmental pollution. Nevertheless, the intensity of the growth of P. pungens needles does not change; therefore, it is not an informative feature for assessing the living conditions of the prickly fir in the industrial zone. The analysis of the micromorphological features of P. pungens needles showed resistance to anthropogenic pressure of its characteristics, such as width and thickness, although the area of needles decreases, which is associated with a significant decrease in the technogenic conditions of the environment of its length. In plants of P. pungens, growing on the territory adjacent to Prydniprovsk TPP, the size of the constituents of needles of P. pungens (epidermis and hypoderms), as well as the number, diameter and type of placement of resin passages in the mesophyll of the needles do not differ significantly from such indices in plants of relatively pure zone indicating the stability of these features and the resistance of the needles of the investigated species to the emissions of TPP. The thickness of the assimilation parenchyma from the adaxial side of the needle of P. pungens in the conditions of technogenesis increases. Among the histological elements of the needles P. pungens the greatest influence of man-made emissions is experienced by the components of the central conductive cylinder: the layer of endoderm thickens by 15,9 %, as compared with the control value, which we consider as an adaptive reaction of plants to man-made stress; the diameter of the central conductive cylinder and the thickness of xylem increases. Probably this is due to the need for better water supply of plants. Thus, in the conditions of technogenesis, stability of the histological characteristics and plasticity of the morphometric characteristics of the needles P. pungens were revealed. The formation of adaptive mechanisms of compensatory type in the needles of P. pungens under the influence of phytotoxicants was found: there is an increase of the size of the endoderm, mesophyll, xylem and the central conductive cylinder of the needles. It is shown that the ratio of particles of histological structures of needles (in %) to the action of pollutants of TPP remains practically unchanged. The informative test parameters for monitoring studies of the condition of coniferous plants in man-made zones (mass, length and area of needles) are suggested. Estimation of P. pungens resistance to the components of the thermal power plant's emissions as a medium-resistant species. It is recommended to use P. pungens in landscaping of contaminated areas.