Physiological parameters formation of drought resistance in the process of adaptation of plants Ulmus pumila L. to adverse environmental factors in the conditions of the Astrakhan region

Background.The studies were carried out in the Astrakhan region, where dust storms are common and there is a deficit of precipitation. Only a few species of trees and shrubs can grow in this region, one of which is Ulmus pumilaL. The adaptation of this species largely depends on the ability to adapt to drought by regulating the internal water environment during the growing season in semi-desert conditions. When there is a lack of moisture in the soil, drought-resistant elm trees have more pronounced protective self-regulatory reactions. Purpose. Assessment of physiological parameters of adaptation of Ulmus pumilaL. to unfavorable environmental factors in the conditions of the Astrakhan region. Materials and methods. The objects were two groups of plants: floodplain plantings and plantings of green umbrellas Ulmus pumilaL. in the Kharabalinsky district of the Astrakhan region. The degree of drought resistance of Ulmus pumilaL. was assessed by the state of water content of the leaves and the functioning of the plant pigment systems in the hot summer period. Results. It was found that the highest indicators of water-holding capacity were observed in plantings of green umbrellas. The chlorophyll content in the leaves of Ulmus pumilaL. varies on average from 31 to 30 mg/cm in two populations. Conclusion. Prolonged drought and high average daily temperatures in the Astrakhan region worsened the indicators of pigments in the leaves, but the life processes of plants in two plantings were stable and no suppression of taxa was observed. Ulmus pumilaL. has a high adaptation to small soils suitable for vegetation in the Astrakhan region.