Abstract: Different concentrations of NaC1 and isoosmotic polyethylene glycol(PEG)were used to treat the seedlings of halophyte Suaede salsa and non-halophyte Prosopis chilensis. Membrane lipid peroxidation malondialdehyde(MDA)content,SOD activity and plasmalemma permeability were determined at different time of treatment. The seedlings of Suaeda salsa showed no or a little response to 0--1. 488 MPa NaCl,but marked response to 1. 984 MPa NaC1. However,there was a greater response to isoosmotic PEG in plasmalemma permeability, SOD activity and MDA content. Prosopis chilensis showed an contrary trend to Suaeda salsa. The MDA content decreased unanimously as three kinds of free-radical scavengers were sprayed on the seedlings of the above plants before NaCl or PEG treatment, but increased with pretreatment of SOD inhibitor. Obviously, the decrease of SOD activity and the increase of MDA content were related to plasma injury, and free-radical did participate the course of salt and/or water stress injury. Their effects of both salt and water stress shared common features in response to the integrity of the cell membrane.

Key words: Salt stress, Water stress, Suaeda salsa, Prosopis chilensis, Membrane lipid peroxidation