Effect of chelating agents and metal ions on nickel bioavailability and chlorophyll fluorescence response in wheat- An approach for attenuation of Ni stress

The objectives of the study are to analyze the physiological changes, biochemical alterations and attenuation of nickel toxicity effects in wheat seedlings under combined applications of Ni ions, metal chelators (EDTA/Citric Acid) and metal ions (Zn2+ /Mg2+). Wheat (Triticum aestivum L cv UP262) seedlings were grown hydroponically using different concentrations of Ni up to 7 days along with chelators and metal ions for study. The seedling growth was maximum with NiCl2–Zn2+ (100μM) and minimum with NiCl2–EDTA (100μM) treatments. Total chlorophyll content was maximum in the seedlings treated with NiCl2-Zn2+ (100μM) and minimum in NiCl2-EDTA (100μM) treatments. NiCl2–EDTA (100μM) showed less Fo and Fm values and therefore, a trend in the decrease in OJIP transient indicates the maximum alteration of photochemical activity of PS-II in presence of NiCl2–EDTA (100μM) treatment. Similar observation was found by NiCl2 –EDTA (200μM) treatment where Fo and Fm values were noted to decline. High nickel content in roots of the seedlings was noted as compared to shoots