ناصر عرب زاده
فضل اله عمادیان
غلامحسین رحمانی

In this research root and shoot osmotic and elastic parameters of Haloxylon aphyllum and Haloxylon persicum after dryness induction were studied. The main goal of the present work was to determine the strength mechanisms of these species against dryness. Pressure chamber technique was applied. Pressure-Volume curves were obtained by this method, and the parameters of water relations were obtained by their analysis. After compatibility with the conditions of garden house environment for one month, a relatively mild dryness was induced to the shrubs by lack of irrigation, so that after 2 weeks the potential of water in the shoot and roots of shrubs of Haloxylon aphyllum was respectively -16.5 and -14 bar, and that of shoot and roots of shrubs of Haloxylon persicum was respectively -14.1 and - 12.2 bar. A relatively harsh dryness was also induced in this same way but after preventing irrigation for 4 weeks, so that water potential in the shoot and roots of Haloxylon aphyllum was respectively -27.2 and -25.1 bar and that of the shoot and roots of Haloxylon persicum was reduced respectively as -25.1 and -23.8 bar. A relatively mild dryness and a relatively harsh dryness were repeated respectively for 6 periods and 11 concurrent periods. Evidence shrubs were irrigated evry 2 days. According to the results obtained, although the induction of relatively mild dryness to the shrubs of both types of Haloxylon increased the elasticity of root and shoot textures, at the same time no changed their osmotic potential. But although a relatively extreme induction of dryness reduced the osmotic potential of root and shoots of both types of Haloxylon and regulated their osmotic parameters, at the same time, increased their elasticity. Key words: Haloxylon, Drought, Resistance, Water potential, Osmotic potential, Tolerance

درختچه ها,هالوکسیلون,مقاومت به خشکی,گونه ها