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A water regime, estimated based on transpiration rate, water content of shoots, concentration of cell sap, and water consumption per unit area, was studied for black saxaul. The seasonal course of black saxaul transpiration during the growing season increased by the middle of summer (July) and decreased towards autumn. The highest transpiration rate of black saxaul was found in Karnabchul, where ground waters poorly mineralized, located at a depth of 14-20 m in nonsaline soils. The lowest transpiration rate was detected in the Nishan steppe, where ground waters were also located at 14-20 m, however they were highly mineralized, and the soil profile was highly salinated. The Southwestern Kyzylkum, characterized by ground waters at a very deep location (more than 100 m) and low soil salinity, occupied an intermediate position in terms of transpiration rate. The maximal water consumption for transpiration during the vegetation period was observed in Karnabchulat 642.5 mm/ha, then in the Nishan steppe at 352.5. The minimal value was detected in the Southwestern Kyzylkum at 171.0.