极端干旱区多枝柽柳茎水势变化影响因子分析

 以新疆塔里木河下游极端干旱环境下天然植物多枝柽柳为研究对象，基于对气象因子、土壤水盐和多枝柽柳茎水势特性的实地监测资料，研究了影响多枝柽柳茎水势变化的主导环境因子，揭示了反映多枝柽柳生长发育期茎干水分变化的环境因子的指示性和指示阈值。结果表明:①在众多环境因子中，土壤水分对多枝柽柳茎水势变化影响最强烈，多枝柽柳对土壤水分的吸收不存在最低土壤含水率阈值，但36%的土壤含水率为影响多枝柽柳茎水势变化的临界上限，超过36%则对其没有明显影响。②土壤pH值的变化可反映极端干旱区多枝柽柳茎水势特性的变化；7.95±0.03的土壤pH值为反映多枝柽柳茎水势发生变化的临界阈值，当土壤pH值大于7.95±0.03时利于多枝柽柳有效分泌盐碱，维持正常生长。该研究为减轻多枝柽柳受旱程度、维持多枝柽柳正常生长及时补充水分提供理论依据。

Factors Affecting Stem Water Potential of Tamarix ramosissima Ledeb. in the Extremely Arid Regions

Based on a series of investigations on weather factors,soil moisture,soil salt content and stem water potential of Tamarix ramosissima,we identified the main environmental factors affecting the stem water potential of T.ramosissima and detected the critical thresholds of the environmental factors.Results show that the soil water content is the most important factor affecting the stem water potential of T.ramosissima among all the environmental factors.There is no minimum threshold of the soil water content for T.ramosissima absorbing water from soil,and the highest threshold of the soil water content is 36%.When the soil water content is higher than 36%,there is no significant change on the stem water potential of T.ramosissima.The change of the soil pH value can reflect the change of the stem water potential of T.ramosissima.The soil pH value of 7.95±0.03 is the critical threshold affecting the change of the stem water potential of T.ramosissima,above which it is advantageous for T.ramosissima to effectively secrete the saline and grow normally.The study can provide crucial empirical data for keeping the normal growth of T.ramosissima.