Abstract: Drought stress and water quality are the main causes of alteration in plant physiological processes and reduction of plant growth. The aim of this study is to evaluate the response of Tamarix aphylla seedlings to two types of irrigation and three periods of water regime under greenhouse condition. The effect of Primary Treated Wastewater (PTW) compared with Well Water (WW) at drought stress using three intervals irrigation on growth, biomass production and its allocation, physical properties and chemical constituents of wood is studied. The experiment was carried out during the successive season of 2010/2011. The results indicate that fresh weight of stem and foliage are increased without any significant for the seedlings irrigated by PTW compared to WW. However, fresh weight of roots and oven-dry weight of foliage are significantly increased. No significant differences are observed for the specific gravity and fiber length of wood produced from seedlings irrigated by either WW or PTW. The results indicated that irrigation with PTW influenced the chemical composition of T. aphylla wood. Under drought stress, all growth parameters and biomass production are decreased by increasing the irrigation periods from one to five weeks. Chemically, the contents of lignin and ash are significantly increased under drought stress; however, the cellulose, extractive and hemicellulose contents express inverse trends. The study conclude that the use of PTW significantly increase the produced biomass and some of wood quality. Planting seedlings under drought stress have significant effects on the properties of one year-old Tamarix seedling.