Abstract:Water physiology and drought-tolerance of Calligonum arborescens,Tamarix ramosissima and Haloxylon ammodendron under drought stress were studied in Taklimakan Desert Highway shelterbelt.Results are as follows:(1)Water potential of 3 kinds seedling was decreased with the increase of drought stress.The biggest drop of water potential were in the second cycle of drought treatment,while in the third cycle of drought,water potential had a greater recovery.C.arborescens had the highest water potential,Haloxylon the lowest.(2)PV water parameters of C.arborescens were decreased with the increase of drought.The osmotic potential in the third cycle of drought began to rise,and the initial plasmolysis relative water content (RWCtlp) showed a decreasing trend.AWC presented a “down-up-down” fluctuating.Drought tolerance of C.arborescens had little change with drought enhanced,it is mainly by reducing water loss adapt to arid environments.(3)T.ramosissima water parameters of PV are little difference between Ⅰ and Ⅱ,but plants withered in the first 60 days treatment Ⅲ.There is little difference in PV water parameters of T.ramosissima between Ⅰ and Ⅱ,treatment Ⅲ first 60 day on dry death.Its Ψsat and Ψtlp reduced in the first period of drought,recovered in the second period,but its apoplastic water content (AWC) was constantly increasing.Drought tolerance of T.ramosissima reduced drastically with enhanced drought,so it is the worst to drought tolerance.It is mainly adapted to arid environments through increased water loss.(4)Ψsat and Ψtlp of Haloxylon were close between Ⅱ and Ⅲ and were lower than Ⅰ.RWCtlp and AWC were increased with the enhanced of drought.AWC of Haloxylon of Ⅱ and Ⅲ were higher than Ⅰduring the same period.Drought tolerance of Haloxylon was enhanced with drought been exacerbated.It coped with drought stress by increasing body water content and reducing water loss.(5)Drought tolerance of three plants is:Haloxylon>C.arborescens>T.ramosissima,so the most suitable desert shelterbelt species is Haloxylon.