Effect of nickel uptake on selected growth parameters of Amaranthus viridis L.

Nickel is an essential element for normal physiological functions in plants. At higher doses (>50 mg/kg, as per WHO) it is toxic to plants and humans, which can bring about oxidative stress affecting the physiological functions of plants and is also considered carcinogenic to human beings. To manage nickel pollution in environment, proper chemical or phytoremediation techniques are required. In this regard nickel accumulator plants would offer a cost effective and environmental friendly phytoremediation method. In the present study, the nickel phyto-accumulation potential of Amaranthus viridis from soil was evaluated to check the tolerance level and the impact on selected morphological parameters like total biomass, plant height, root length and number of leaves. Nickel uptake by A. viridis was studied from Ni contaminated soil amended with20, 40, 60, 80 mg/Kg of Ni exposure under controlled conditions. Toxic effects and tolerance of the plant to toxic doses of nickel was evaluated by correlating the uptake per gram of biomass with various parameters of plant like its height, biomass, root length and, number of leaves.  Supply dependent maximum nickel uptake of 108 µg/gm and corresponding decrease in growth parameters were recorded up to 60 mg/Kg exposure. This study indicates the uptake of nickel by A. viridis increases with increase in supply up to 60mg/kg and beyond 60 mg/kg, the uptake decreases. The study also shows uptake of nickel per gram of biomass has a significant  negative correlation mainly with parameters like plant height (R= -0.71 at 0.05 level of significance) and total biomass (R = -0.83 at 0.05 level of significance) where as other parameters like length of root and number of leavers are not significantly affected (P>0.05) with uptake of nickel per gram of biomass.