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.