RESUMO
The continuous increase in the heavy metals concentration in the soil due to anthropogenic activities has become a global issue. The chromium, especially hexavalent chromium, is highly toxic for living organisms due to high mobility, solubility, and carcinogenic properties. Considering the beneficial role of nanoparticles and bacteria in alleviating the metal stress in plants, a study was carried out to evaluate the role of cerium dioxide (CeO2) nanoparticles (NPs) and Staphylococcus aureus in alleviating the chromium toxicity in sunflower plants. Sunflower plants grown in chromium (Cr) contaminated soil (0, 25, and 50 mg kg-1) were treated with CeO2 nanoparticles (0, 25, and 50 mg L-1) and S. aureus. The application of Cerium Dioxide Nanoparticles (CeO2 NPs) significantly improved plant growth and biomass production, reduced oxidative stress, and enhanced the enzymatic activities in the sunflower plant grown under chromium stress. The application of S. aureus further enhanced the beneficial role of nanoparticles in alleviating metal-induced toxicity. The maximum improvement was noted in plants treated with both nanoparticles and S. aureus. The augmented application of CeO2 NPs (50 mg l-1) at Cr 50 mg kg-1 increased the chl a contents from 1.2 to 2.0, chl b contents 0.5 to 0.8 and mg g-1 FW, and decreased the leakage of the electrolyte from 121 to 104%. The findings proved that the application of CeO2 nanoparticles and S. aureus could significantly ameliorate the metal-induced stress in sunflower plants. The findings from this study can provide new horizons for research in the application of nanoparticles in phytoremediation and bioremediation.
RESUMO
Cadmium (Cd) toxicity strongly influences plants growth and seed germination in crop plants. This pot trial had aimed evaluate the benefits of two different kinds of phosphorus (P)-fertilizer in the phytoremediation of Cd by Solanum nigrum L. The current pot experiment was conducted to evaluate the role of P-fertilizers in phytoremediation of Cd by Solanum nigrum L. Single superphosphate (SSP) contain 7 to 9% P and Di-ammonium Phosphate (DAP) contain 46% P had been applied in single and combine form in soil with different ratios (0:0, 100:0, 0:100, 50:50%) accompanied by diverse Cd levels (0, 25, 50 mg kg-1). Three weeks seeding were transferred into pots, and plants had been harvested afterward seventy days of growth in the pots. Significantly inhibited plant growth was observed in shoots and roots of Cd contaminated plants. Cadmium stress had stimulated oxidative stress in subjected plants. However, supplementation of P-fertilizers in an optimum manner significantly increased plant biomass along with enhancing antioxidants enzymatic activities and inhibiting oxidative stress. Maximum plant-growth had been noted in SSP + DAP supplemented plants in contrast to single SSP, DAP supplemented plants. Higher Cd concentrations observed in SSP + DAP supplemented plants over single treatment. It has been concluded that combination of SSP + DAP might be a better option to improve growth as well as uptake capacity of Solanum nigrum L. under Cd stress. However, a field study is recommended for detailed future investigations.