Abstract: Wheat seedlings (Tritium aestivum "No. 1 Yuyuan") with 3 leaves were transplanted to 1/2 strangth Hoagland nutrient solution containing 100 mmol/L NaCl and supplemented with different concentrations of CaCI2, which were mode isosmotic by adding polyethylene glycol (PEG) and aerated by pump. Results showed that the Na+ content of shoots and roots, relative leaf expansion rate, plasma membrane permeability, the levels of membrane lipid superoxidation and the molar percentage of monogalacrosyl diglyceride(MGDG), digalactosyl diglyceride(DGDG) phosphatidyl choline(PC) and phosphatidyl ethanolamine(PE) in membrane lipids of roots increased, the plant dry weight, K+ content, SOD activity and the molar percentage of phosphatidic acid(PA), phospatidyl inositol (PI), phosphatidyl glycerol(PG) and polyphosphoglyceric acid(PPG) decreased in roots. There was no change in sulfolipid(SL). However, the above mentioned salt injury effects were all alleviated by the different Na+/Ca2+ ratios. The maximum alleviation of salt injury effect was at Na+/Ca2+ ratio of I0. As three kinds of free radical scavengers were used to pretreat wheat seedlings prior to NaC1 treatment the malondialdehyde(MDA) content decreased unanimously, but increased with SOD inhibitor sodium diethyldithiocarbamate (DDTC) pretreatment to wheat seedlings. Obviously, the salt injury effects induced by NaC1 was relatied to the extent of superoxidation of membrane [ipids and also to the composkion of membrane of Ca2+ on lipids including their fatty acids as well. On the other hand, the alleviating effect of Ca2+ on NaC1 induced injury in wheat seedlings was also in relation to them.

Key words: Na/Ca ratio, Wheat seedlings, Plasma membrane permeability, Menbrane lipids superoxidation, Membrane lipids component