盐胁迫下三角叶滨藜根系超滤特性的分析

对耐盐蔬菜三角叶滨藜(Atriplex triangularis)在盐胁迫下的蒸腾吸水量、Na+吸收和根系径向反射系数进行了测定,分析其根系超滤特性与植物耐盐性的关系。结果表明,随着盐胁迫强度的增加,三角叶滨藜的Na+吸收量逐渐增多、蒸腾吸水量和根系径向反射系数则逐渐降低;但以根外溶液盐浓度为基础的Na+相对吸收量却呈降低趋势,同时进入木质部的Na+的量也不随根的径向反射系数的减小而显著增多。说明三角叶滨藜在盐胁迫下一方面通过改变根系的超滤特性,降低根系径向反射系数来防止木质部拉力过大导致的木质部空化的危险,另一方面通过减少对盐分的吸收来避免盐分过多积累对植株的伤害。

Ultrafiltration characteristics of roots of arrowleaf saltbush under salt stress

Salt absorption, transpiration induced water uptake and the radial reflection coefficient of the root system of arrowleaf saltbush (Atriplex triangularis) were measured in order to analyze ultrafiltrational characteristics of its root system in relation to salt tolerance of the plant. Results show that increase in salinity stress in the root environment resulted in increase in Na⁺ uptake, and decrease in transpirational water uptake and in radial reflection coefficient as well. However, the relative amount of Na⁺ uptake based on the salt concentration of the solutions from root bathing showed a tendency of declining with the increase in salinity stress. The amount of Na⁺ being taken into the xylem did not exhibit any significant increase with the decreasing radial reflection coefficient of the root. This indicated that arrowleaf saltbush was able to change the ultrafiltration characteristics of its root system and reduce radial reflection coefficient of the root, thus lowering the risk of higher xylem tension leading to xylem cavitation and able to reduce salt absorption to avoid damage of salt over-accumulation to the plant.