Influence of urban environment factors on morphometric parameters and accumulation of secondary metabolites in Cercis canadensis L. and Cercis siliquastrum ‘Alba’

Abstract

Consideration of the role of green spaces in urban landscaping is extremely important, as they not only decorate the urban landscape, but also effectively reduce air pollution, regulate the microclimate and play an important role in improving the ecology and quality of life of residents. The purpose of the study was to determine the influence of urban environmental factors on the development and secondary metabolism of plants of the genus Cercis L. Plants growing in Kyiv (Ukraine) under conditions with different air humidity, anthropogenic load, and excess or lack of insolation were selected for the study. Plant growth processes were studied by morphometric parameters of annual shoots of Cercis siliquastrum ‘Alba’ and Cercis canadensis L. growing under different conditions. Morphometric methods, fluorescence microscopy, high-performance thin-layer chromatography and regression analysis were used in the study. The research data show that insufficient sunlight has a negative impact on shoot growth. The specificity of the phenolic profiles that can be used to distinguish between the species Cercis canadensis L. and Cercis siliquastrum ‘Alba’ was established. The principal component analysis confirmed that phenolic profiles depend on habitat conditions and affect plant growth and development. The Gaussian model was used to analyse the growth dynamics of annual shoots during the growing season, which allowed us to describe the specifics of internode formation during the growing season quite accurately. This model allowed us to detect the phenomenon of the last internodes falling off at the end of the growing season, which caused the deviation of the morphometric parameters of metameres from the normal distribution along the time axis. Anatomical studies confirmed that the separation of one or more of the last internodes was due to active corking of the internal tissues of the stem, blocking of the xylem and formation of a separating layer, which led to the fall of the shoot tip. This phenomenon shows signs of plant adaptation to low temperatures in winter. The tops of the shoots often do not have time to lignify and accumulate the required amount of cryoprotectants. With the formation of a separating layer, the available energy resources are redistributed to the lateral buds, which receive the necessary resources to prepare for the winter period and provide new growth in the next growing season. The adaptive potential of the two species of the genus Cercis L. confirms the prospects of their use in urban ecosystems, which can positively affect the conservation of biodiversity in general