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.