How Nano Silica Helps Marigolds Absorb Less Heavy Metals

Jim Crocker
25th June, 2024

How Nano Silica Helps Marigolds Absorb Less Heavy Metals

This scanning electron microscope image reveals the spherical and porous structure of the nano silica particles, which enhances their capacity to absorb heavy metals.

Image adapted from: Samani et al. / CC BY (Source)

Key Findings

  • The study by the University of Zanjan found that applying 1000 mg/kg of nano silica increased soil pH by 6%, reducing the availability of heavy metals
  • Nano silica reduced the concentrations of lead, zinc, copper, nickel, and chromium in the soil by 12%, 11%, 11.6%, 10%, and 9.5%, respectively
  • Nano silica improved plant health by increasing phosphorus and potassium uptake by 25% and 26%, respectively, and enhancing soil enzyme activities
Soil contamination with heavy metals is a pressing issue that affects plant health and human well-being. Heavy metals such as lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), and chromium (Cr) can accumulate in plants, leading to reduced growth and potential health hazards when these plants enter the food chain. A recent study by the University of Zanjan explores the use of nano silica as a solution for mitigating heavy metal uptake in Calendula officinalis[1]. The study conducted greenhouse experiments to assess the impact of nano silica on heavy metal uptake and plant health. The researchers found that applying 1000 mg/kg of nano silica increased soil pH by 6% compared to the control treatment. This increase in soil pH is significant because it can influence the availability of heavy metals in the soil. The results showed that nano silica at this concentration decreased the concentrations of available Pb, Zn, Cu, Ni, and Cr in the soil by 12%, 11%, 11.6%, 10%, and 9.5%, respectively, compared to the control. One of the key findings was that nano silica significantly reduced heavy metal accumulation in C. officinalis, except for zinc. In fact, in the 1000 mg/kg nano silica treatment, Zn concentrations in shoots and roots increased by 13.28% and 13%, respectively, compared to the control. This suggests that while nano silica is effective in reducing the uptake of most heavy metals, its effect on zinc uptake is different and requires further investigation. In addition to reducing heavy metal uptake, nano silica also improved the overall health of the plants. The application of nano silica led to a 25% increase in phosphorus (P) and a 26% increase in potassium (K) uptake by the plants. These nutrients are essential for plant growth and development. Furthermore, the highest amount of urease enzyme activity was 2.5% higher, dehydrogenase enzyme activity was 23.6% higher, and alkaline phosphatase enzyme activity was 13.5% higher in the 1000 mg/kg nano silica treatment compared to the control. The findings of this study are consistent with previous research on the use of natural compounds and plant growth regulators to mitigate heavy metal stress in plants. For instance, earlier studies have shown that proline, an osmoprotectant, can improve the growth, photosynthetic performance, and antioxidant capacity of wheat plants exposed to Ni stress[2]. Similarly, the combined application of indole-3-acetic acid (IAA) and compost has been found to alleviate the adverse effects of Ni on cauliflower by reducing Ni uptake and improving plant attributes such as height, root length, and chlorophyll content[3]. Moreover, the use of plant hormones like abscisic acid (ABA) and 6-benzylaminopurine (6-BAP) has been shown to enhance plant growth and reduce oxidative stress in rice plants exposed to chromium contamination[4]. These studies collectively highlight the potential of various natural compounds and growth regulators in mitigating heavy metal stress in plants. The current study by the University of Zanjan builds on these findings by demonstrating the effectiveness of nano silica in reducing heavy metal uptake and improving plant health. The increase in soil pH and reduction in available heavy metals in the soil indicate that nano silica can immobilize heavy metals, making them less available for uptake by plants. This is crucial for preventing the accumulation of toxic metals in edible plant tissues. In conclusion, the application of nano silica at a concentration of 1000 mg/kg has been shown to enhance root and shoot length, dry weight, and soil enzyme activity in C. officinalis. It also increased the uptake of essential nutrients like phosphorus and potassium while reducing the uptake of harmful heavy metals. These findings suggest that nano silica could be a promising solution for mitigating heavy metal contamination in soils, thereby contributing to sustainable agriculture and improved plant health.

EnvironmentBiotechPlant Science

References

Main Study

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

Published 25th June, 2024

https://doi.org/10.1186/s12870-024-05311-1

Related Studies

2) Proline-mediated redox regulation in wheat for mitigating nickel-induced stress and soil decontamination.

https://doi.org/10.1038/s41598-023-50576-5

3) Exploring the synergistic effects of indole acetic acid (IAA) and compost in the phytostabilization of nickel (Ni) in cauliflower rhizosphere.

https://doi.org/10.1186/s12870-024-04920-0

4) Mitigating chromium toxicity in rice (Oryza sativa L.) via ABA and 6-BAP: Unveiling synergistic benefits on morphophysiological traits and ASA-GSH cycle.

https://doi.org/10.1016/j.scitotenv.2023.168208


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