ADAPTIVE VARIABILITY OF PRUNUS ARMENIACA L. NATURAL CENOPOPULATIONS BY LEAF MORPHOLOGICAL TRAITS ALONG AN ALTITUDE GRADIENT (DAGESTAN)

The article presents the results of a study of the adaptive variability of morphological traits of leaves of natu- ral cenopopulations of Prunus armeniaca L. (common apricot) along the altitudinal gradient using the example of Intramountain Dagestan. Three model cenopopulations of Intramountain Dagestan along the Avarskoye Koysu River basin, which differ most strongly along the altitudinal gradient (600–1420 m above sea level), were selected as reference points. Analysis of the adaptability of P. armeniaca cenopopulations in the conditions of Dagestan showed a significant role of the altitude above sea level on the variability of leaf morphological traits. It was found that the greatest dependence on the altitude gradient have the traits “width of the leaf blade” and “length to the wide part of the leaf,” as well as index indicators calculated on their basis. Analysis of the variability of quan- titative leaf traits by the variation coefficient (CV, %) showed that the variability of traits decreases along the alti- tude gradient, which may indicate a decrease in the population optimum of the species with altitude above sea level. The results of the comparative analysis were confirmed by the results of ANOVA and regression analyses. The variance components for the ovoidness indices were 62.8%, and roundness – 37.1%, leaf width – 22.5%, length to the wide part of the leaf – 17.4% and SLA – 15.6%. Based on the results of regression analysis, it was revealed that the altitudinal level negatively effects on the leaf size of natural coenopopulations of P. armeniaca by narrowing of the leaf width and shortening of the length to the wide part of the leaf, which ultimately results in the formation of oval-ovate leaves. The determination coefficients (r2 ) showed a noticeable linear relationship be- tween the selected traits and the altitudinal gradient, with the exception of leaf width. The index of vitality of cenopopulations (IVC) showed a deterioration in growing conditions in the direction from low-mountain cenopopulations to mid-mountain ones (from 1.04 to 0.96), while the low value of dimensional plasticity (ISP=1.08) indicates the relative stability of leaf traits along the altitudinal gradient.