Nano silica's role in regulating heavy metal uptake in Calendula officinalis.

Background: Soil contamination with heavy metals poses a significant threat to plant health and human well-being. This study explores the potential of nano silica as a solution for mitigating heavy metal uptake in Calendula officinalis.

Results: Greenhouse experiments demonstrated, 1000 mg•kg nano silica caused a 6% increase in soil pH compared to the control treatment. Also in 1000 mg. kg nano silica, the concentrations of available Pb (lead), Zn (zinc), Cu (copper), Ni (nickel), and Cr (chromium) in soil decreased by 12%, 11%, 11.6%, 10%, and 9.5%, respectively, compared to the control. Nano silica application significantly reduces heavy metal accumulation in C. officinalis exposed to contaminated soil except Zn. In 1000 mg.kg nano silica shoots Zn 13.28% increased and roots Zn increased 13% compared to the control treatment. Applying nano silica leads to increase the amount of phosphorus (P) 25%, potassium (K) 26% uptake by plant, In 1000 mg.kg treatment the highest amount of urease enzyme activity was 2.5%, dehydrogenase enzyme activity, 23.6% and the highest level of alkaline phosphatase enzyme activity was 13.5% higher than the control treatment.

Conclusion: Nano silica, particularly at a concentration of 1000 mg.kg , enhanced roots and shoots length, dry weight, and soil enzyme activity Moreover, it increased P and K concentrations in plant tissues while decreasing heavy metals uptake by plant.