The effect of some soil physical properties on plant growth index of black saxaul Haloxylon aphyllum

Regeneration of black saxual (Haloxylon aphyllum) is an important project for sand dune fixation in desert area of Iran. Success of this project is largely depending on climate conditions and soil physical properties. In order to determine some inhibitor factors of black saxual growth, a project were conducted in a 2 ha black saxual site in Semnan, Iran. Morphological traits as: plant height, canopy cover, collar diameter and collar first sympodial interval and growth index were recorded on 5 year old shrubs. At the mean time soil properties as: EC, pH, SP and Texture (silt, clay, sand), were measured. The relationships among plant growth indices and soil properties showed a negative correlation (P0.05) between growth index and saturation percent (SP). It was concluded that SP factor was the most important factor to inhibit black saxual growth in Semnan province, Iran.