Characteristics of The Assimilation Apparatus of Species From the Genus Picea A. Dietr. In The Conditions of Different Pollution Levels

In the course of our investigations, we have found a suppressed state of assimilation organs in the trees of Picea abies and P. pungens from plantations with moderate and high pollution levels. It causes a decrease of morphometric characteristics (needle length, width, thickness, cross-section perimeter, surface area, and shoot length) and anatomical parameters [thickness of the epidermis, hypodermis, endoderm, diameter of central conducting cylinder (CCC), resin duct numbers, and their diameter] in both species. However, regarding the endoderm thickness and central conductor cylinder indices in P. pungens in conditions of urban technogenic environments, we observed an increase of these parameters in contrast to P. abies, which can be explained as the adaptive response spruce species to technogenic stress. It is shown that the higher pollution levels in both species cause 1.6-fold decrease in shoot length and 1.4 times shorter needle lifespan, respectively, along with worsening of tree ornamental traits. At the same time, a 1.3-fold increase in the needle number per shoot was observed as compared to the control being probably an adaptive response to adverse environmental conditions. Our investigations have shown that emissions from industry and transport suppress anatomical and morphometric indices of two-year-old needles and shoots of second order in P. abies and P. pungens, but the latter species demonstrates anatomical changes of adaptive nature.