三角叶滨藜根吸水特点与其抗盐性的关系

采用压力室和冰点渗透压计测定了三角叶滨藜在不同浓度NaCl的根系环境溶液中根木质部的压力势和伤流液的渗透势,并利用原子吸收分光光度计测定了植株和伤流液以及环境溶液中Na 含量。结果表明:随着根环境溶液NaCl浓度的增加,三角叶滨藜植株和木质部伤流液中Na 含量虽呈上升趋势,但根系的过滤系数和体内Na 相对累积量逐渐降低,说明三角叶滨藜根细胞对盐分有很强的过滤作用;木质部伤流液的渗透势随着环境溶液渗透势的降低而降低,但根木质部溶液的水势则逐渐高出根外环境溶液的渗透势;表明三角叶滨藜能够利用较低的木质部负压来抵抗根外溶液的低渗透势而反渗透吸水,并利用根细胞对盐分的过滤作用来避免从环境摄取过量的盐分。

Characteristics of water absorption by Atriplex triangularis roots under salt stress

In this study, Atriplex triangularis plants were grown in a nutrient solution containing different concentrations of NaCl, and the pressure potential of root xylem, osmotic potential of its sap, and Na contents in plant, sap and nutrient solution were measured with pressure chamber, freezing-point osmometer, and atomic absorption spectrometer, respectively. The results showed that with the increasing salinity of nutrient solution, the Na content in plant and in xylem sap increased, but the ultrafiltration coefficient of root system and the relative accumulation amount of Na in plant decreased, illustrating that the root cells of A. triangularis had a strong filtration action. The osmotic potential of root xylem sap decreased with decreasing osmotic potential of nutrient solution, but the water potential (osmotic potential plus pressure potential) of the solution in root xylem increased steadily till higher than the osmotic potential of nutrient solution. It was concluded that A. triangularis could use the lower negative pressure in root xylem to absorb water via anti-osmosis to counteract the low osmotic potential of nutrient solution, and avoid the absorption of excess amount of salt via high-efficient ultrafiltration of root cells.