Abstract: Four-day-old corn (Zea mays L. ) seedlings, which had grown in aerated 0.5 x Hoagland solution (pH 5.7) in dark were stressed by 50, 100 and 150 mmol/L NaCI solution for 6, 12 and 24 h respectively. The root segments (0 to 20 mm from the tip) were sampled for study. The results showed that the relative elongation rate (RER), H+-extrusion rate and Fe(CN)3-6 reduction rate of the roots declined with the increase of NaC1 concentration, but H+-extmsion rate restored somewhat with the time course. NADH oxidation rate increased up to 12 h with the increase of NaC1 concentration and then decreased significantly, while under the same concentration of NaC1 NADH oxidation rate decreased with the time course. The relative coeffecient (r) of RER and H+-extrusion rate under NaCI stress was 0.999 8. Therefore, it is suggested that the inhibition of the elongation growth by NaC1 stress is closely related to the inhibition of redox system and H + -ATPase activity of plasma membrane.

Key words: NaC1 stress, Corn roots, H+-extrusion, Redox system