Ni accumulation and its effects on physiological and biochemical parameters of Eichhornia crassipes

• E. crassipes accumulated Ni(II) efficiently both in roots and leaves.
• E. crassipes maintained its photosynthetic activity under Ni stress.
• E. crassipes developed a rapid response to Ni accumulation by increasing the antioxidant enzyme system.
• Oxidative damage occurred at Ni concentrations higher than 3 mg l−1.
• E. crassipes could grow under Ni(II) stress and protect itself by altering metabolic processes.

Ni accumulation and concomitant physiological and biochemical responses were studied in Eichhornia crassipes 1 exposed to different concentrations (1, 2, 3 and 4 mg l−1 Ni) for 72 h. E. crassipes 1 rapidly sorbed Ni during the first 24 h. Ni concentration in roots was significantly higher than in aerial parts. Continuity of the photosynthetic activity was observed by a significant increase of pigment concentrations during the first 48 h, followed by a decrease at 72 h. In aerial parts, MDA concentration increased significantly during first 48 h at the highest Ni concentration exposure. However, was evidently counteracted by the compensatory protective mechanism of increased antioxidant enzyme activities. In roots, a significant increase in enzyme activities of antioxidant system did not prevent lipid peroxidation observed by an increase in MDA concentration at 72 h of exposure. Our results suggest that E. crassipes 1 was able to tolerate Ni stress increasing the activity of its antioxidant system at short exposure times and low Ni concentrations studied.