Fig. 4.

Root elongation rates in stress-relief experiments. Plants were grown in Hoagland solution for 4 d and gradually treated with either 150 mm NaCl or 300 mm sorbitol. Average elongation rates (4 h) were measured on day 6, before and after transfer to a hypo-osmotic medium. The dashed lines across the figures indicate the mean elongation rate before transfer, the bars represent elongation rates after transfer; results are means of 34–119 roots. (A) Roots kept in 150 mm NaCl, or transferred to medium containing 75 mm NaCl (150 → 75) with the following additions as indicated: 50 µm DPI, 10 mm MnCl₂, 50 mm Tiron, a Fenton mixture (0·2 mm ascorbate + 0·2 mm CuCl₂ + 0·2 mm H₂O₂ ) or 100 µm H₂O₂. (B) Roots kept in 300 mm sorbitol, or changed to medium containing 150 mm sorbitol (300 → 150) with the following additions as indicated: 50 µm DPI, 10 mm MnCl₂, 50 mm Tiron. Different letters indicate significant differences among elongation rates after transfer within each stress treatment (P < 0·05).