CHANGE OF SMALL-LEAFED LIME'S PHENOTYPIC FEATURES IN URBAN ENVIRONMENT
The influence of air pollution with industrial emissions on small-leafed lime has been investigated, because lime tree's leaf is very sensitive to environmental pollution. Changes of lime lamina phenotypic features in various places of its habitat in Vladikavkaz under different level of pollution have been studied. During five years, at 5 plots which were located in various distance from sources of industrial pollution, the leaf's morphometric parameters (petiole length, leaf length, width and its size) (Nikolaevskiy, 1966; Nikolaevskaya, 1999; Kulagin, 1974), veins' number and length (Nikolaevskiy, 1996) have been taken into account. Leaf shape, noting the degree of its asymmetry has been also analyzed. Both fresh and dried leaves of annual shoots have been the subject of our analysis. Slightly contaminated plot located far away from industrial plants and motor high-ways with index of air pollution (API) of 2,0 was a control sample. Every year on experimental plots situated in different places with various level of air pollution, leaves from the 2 sides of each of the 8-9 model trees - not less than 50 pieces from the each side of the tree, in total 25,000 samples, have been selected. Determination of leaf lamina size was made at the end of July (after growth processes cessation) at different streets with various level of air pollution. Atmospheric pollution influences the size of leaf lamina. The higher is the level of air pollution, the smaller is the leaf size. Side shoots' leaves are less affected to this influence. The number of leaf veins is an indicator of the level of leaf anatomical structure variability under the influence of air pollution. Thus, in areas with a high level of API, there is a clear tendency to the reduction of veins number, regardless of leaf proportions. We have also established that leaf thickness depends on the API index - the higher is the API index, the less is the leaf thickness.