Fig. 5.

a-d. Impact of Pb and Hg on magnitude of oxidative stress (a) and changes in activities of ascorbate peroxidase (APX, b), catalase (CAT, c) and glutathione reductase (GR, d). Enzyme actities have been expressed in enzyme units (EU) mg^− 1 protein min^− 1 in soybean root nodules exposed to Pb (30 ppm) and Hg (0.5 ppm). All data are presented as the mean ± standard error (SE). The measurements were made using five biological replicates. The statistical analyses were carried out using one-way analysis of variance (ANOVA) and means were compare using Tukey’s test. NS = Non-significant, *P ≤ 0.05 and **P ≤ 0.01