Abstract

Osmotic parameters of Haloxylon aphyllum were studied after inducing dryness. Water relations parameters with improving resistance to dryness of this species through inducing severe dryness and clarification of physiologic mechanisms of this plant in response to a low water and dryness were among the objectives of this study. For this purpose, the method of pressure chamber was employed. By this method, the pressure-volume curve was drawn and the parameters of water relations of the plant were obtained from analyzing them. A relatively mild dryness was induced to plants through a lack of irrigation. After two weeks, Haloxylon water potential reached -16.5 bars. A severe dryness was also induced to that but after four weeks of no irrigation, it was reduced to -27.2 bars. Relatively mild and severe dryness were repeated for six and 11 periods respectively. In both series of experiment, the control water potential that were being watered every two days once, remained fixed at about -12.7 bars. Based on the results, although the relatively mild dryness increased the elasticity of plant textures, but it had not a meaningful impact on its osmotic potential. Although the use of a relatively severe dryness decreased both osmotic potential and osmotic adjustment, but at the same time, it increased the elasticity too.

Key words: Haloxylon, water relations, water stress, drought resistance, osmotic potential, elasticity.