Hawthorn in the Arid Conditions of Dagestan

The common hawthorn (Crataegus rhipidophylla Gand.) is a typical representative of arid woodland species of Piedmont Dagestan. It grows in the lower, middle, and upper mountain zones. Identification of patterns of intraspecific and interpopulation diversity, including quantitative traits of annual shoots and their adaptive manifestations under conditions of introduction, makes it possible to determine the optimum of the species and the adaptive potential to specific arid growing conditions. The results of an ecological–geographical experiment on the altitudinal gradient of common hawthorn using the example of an annual shoot are presented. This study was carried out using a unique research assembly “System of experimental bases located along an altitude gradient (1100 and 1700 m above sea level).” Plants grown from seeds collected in different conditions of arid areas were studied. To study adaptive changes using the example of an annual shoot under introduction conditions, ten quantitative traits and one qualitative trait (hairs) of the shoot and leaf were studied. The research results were processed and evaluated using descriptive statistics, correlation, cluster, and two-factor analysis of variance. The degree and structure of variability in the quantitative traits of the annual shoot and leaf were revealed, and the presence of population–geographic differentiation was established based on the traits of “shoot length,” “number of leaves,” and “number of thorns” depending on the germination conditions of the samples. Differences between the samples in terms of the quantitative and qualitative characteristics were determined; with growing altitude above sea level, the increase in the “number of thorns” and hairs on the shoot and leaf can be considered as one of the adaptive mechanisms of vegetative organs to the abiotic factors of the arid climate in mountain conditions.