Fig. 4From: Characterisation of early responses in lead accumulation and localization of Salix babylonica L. rootsDistribution of PI fluorescence density detected by Image J in different zones of S. babylonica roots treated with 100 μmol/L Pb for 3, 6, 12, and 24 h. Vertical bars denote the SE. Different letters indicate significant differences (p < 0.05)Back to article page