Abstract: There exists a redox system at the surface of the roots and shoots in winter wheat． The oxidation rate of NADH of the shoots is the highest at the fastest growth stage under normal water supply．The growth of roots and shoots is significantly inhibited under osmotic stress．In plasma membrane of roots and shoots，the force of reducing K₃ Fe(CN)₆ is increased under stress，and that of shoots is m ore stimulated，however，the oxidation rate of NADH is higher than that of control at the stress beginnings and final stages，and no significant differences is observed at other periods．