Growth and Metabolic Responses of Rhazya stricta Decne to Habitat Diversity in Makkah Region, Saudi Arabia

THE PRESENT study is an attempt to clarify the effect of habitat (Mountain, plain and wadi) diversity on growth behavior and metabolic activities of one common perennial dwarf shrub (Rhazva stricta). Plain was attained the highest moisture availability and lowest salt stress while the highest content of coarse sand recorded in wadi which led to loss water, mountain holds in its notches an adequate amount of moisture for growth of some species. Leaf area, height of plant, crown diameter, and the biomass of above ground organs furthermore, abundance measurements (absolute density, frequency and cover) were significantly varied with habitat types. The favorable habitat types for the plant growth and productivity were plain and wadi as compared with mountain. Carbohydrates and proteins (total and soluble) in different phenophases of plant were significantly varied with habitat types. The highest essential elements in all studied habitats for the plant organs (root, leaves) were Ca and K. In mountain K/Na ratio is low in mountain compared with the other habitats. This result may indicate that the plant in mountain use sodium as osmoregulatory substance, while in plain and wadi the contribution of K to the osmotic balance is larger than Na. Total flavonoids, total phenolics and essential oil were accumulated more in the plant which grow under sever mechanical stress (mountain habitat type).