Abstract: Plant hydraulic lifting is a phenomenon that the roots in deep wet soil uptake water from subsoil and carry water though the transport tissues to the roots in topsoil and into dry topsoil around them when transpiration is lower at night. The method in which the roots were separated into those in topsoil and subsoil was used to study the hydraulic lifting of Populus euphratica seedling roots in their whole growing season. The results are as follows; (1) There is a hydraulic lifting function in roots of P. euphratica seedlings; (2) Hydraulic lifting occurred from 21:00  to 6:00 am next morning. The total uptake water volumes of the seedling roots of 3 P. euphratica plants in growing season were 2.78, 2.31 and 2.46 kg, and their average daily volumes were 0.022 6, 0.018 7 and 0.020 kg, respectively; (3) The proportion of hydraulic lifting water volume of P. euphratica seedling roots varied in a range of 13%-20% of evaporation from topsoil. During the period from June to August when transpiration was significant, the average daily hydraulic lifting water volume was also high; (4) There was a significant correlation between root biomass and hydraulic lifting water volume in subsoil.

Key words: Populus euphratica, seedling root, hydraulic lifting, transpiration, desert riparian forest area, Tarim River