Physiological changes of three woody plants exposed to progressive salt stress

The saline character of water imposes restrictions on plant growth and survival in the Taklamakan Desert, China. Experiments were conducted on woody plant species, Tamarix ramosissima, Populus euphratica, and Haloxylon ammodendron grown under different levels of salinity to elucidate their adaptation to a saline environment. H. ammodendron accumulated large amounts of Na+ and Cl- in leaves. P. euphratica restricted redundant Na+ and Cl- transport to the shoots treated with lower NaCl concentrations. Na+ in leaves of T. ramosissima accumulated significantly only under higher NaCl concentrations (>= 200 mM NaCl). The analyzed plants' exposure to high saline concentrations induced oxidative stress as evidenced by the increase of H2O2 and malondialdehyde and changes in photosynthetic pigments, gas-exchange characteristics, and antioxidant enzyme activities. T. ramosissima and H. ammodendron exhibited a greater ability to adapt to saline-induced oxidative stress due to more efficient antioxidant enzyme system to prevent oxidative damage.