Effect of salinity on concentrations of hydrogen peroxide (A) and superoxides (B) along the maize leaf elongation zone. The plants were grown at 1 mM NaCl (control) or 80 mM NaCl (salt). Data are means ± SE (n=5). If not shown, error bars are smaller than the symbol size. Asterisks represent significant difference of salt stress treatment vs, control for each equivalent position along the elongation zone (P<0.05). The horizontal bars underneath the figure represent the two zones analyzed by SSH.