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Cadmium binding and soil microbial diversity in Vetiveria zizanioides

Cd on soil microbial communities. Interestingly, the (i) Root extraction and disposal. It is recommended
population of Proteobacteria was found to increase in that if feasible, the root system of the plant should
the presence of V. zizanioides, indicating a potential be completely removed to prevent the re-release of
synergy between these bacteria and the plant, similar to Cd into the environment. The roots should then be
findings by Calcagnile et al. for Salix species, which disposed of properly, for instance, by incineration
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also demonstrated an increase in Proteobacteria under at high temperatures or burial in hazardous waste
Cd stress. This finding is consistent with Long et al. landfills to ensure that Cd does not leach into other
31
who reported that Proteobacteria was the dominant areas (Phytoremediation Resource Guide, 1999). 50
bacterial group in soil planted with V. zizanioides. (ii) Soil remediation after root removal. After root
In contrast to V. zizanioides, Populus species have extraction, the soil can be treated using methods like
been found to boost the microbial diversity of beneficial soil washing, bioremediation with microorganisms,
fungi and bacteria in Cd-contaminated soils, a or the addition of amendments (e.g., biochar,
mechanism that contributes to improved bioremediation compost) that can immobilize the residual Cd and
efficiency. Similarly, the cultivation of Populus species reduce its bioavailability. This ensures that the
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resulted in a significant increase in beneficial microbial remaining Cd in the soil does not become accessible
activity, leading to improved phytoremediation to plants. 51
potential. While the findings for V. zizanioides indicate (iii) Long-term monitoring. Even after root extraction
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that Cd negatively impacts plant growth and microbial and soil treatment, continuous monitoring of Cd
diversity, investigations on other species like Populus, levels in the soil is essential. Periodic soil testing
Salix, and C. arietinum provide additional insights into will help determine if any Cd remains or if additional
the complex interactions between plants, microbes, and remediation is required to ensure soil health and
HMs. Future studies should continue exploring a broader
range of species to better understand the full potential of prevent re-contamination. Completely removing
phytoremediation and bioremediation processes. the root system is ideal to prevent re-contamination,
On the other hand, extrapolating results from but if this is not possible, treating the soil and
laboratory or greenhouse experiments to field monitoring it over time for cadmium levels should
conditions is a challenging task, especially in the be prioritized to ensure long-term soil safety.
context of HM remediation. Controlled environments,
such as pot cultures, provide valuable insights but fail 5. Conclusion
to replicate the complexities of natural ecosystems,
where factors such as soil heterogeneity, microbial In the present study, the effect of V. zizanioides on
diversity, and environmental variability influence the Cd-contaminated soil microbial structure was
remediation processes. Studies have shown that while investigated. First, the plant growth on the different Cd
laboratory conditions can demonstrate the potential for concentration was studied by measuring the leaves and
phytoremediation, field studies are crucial to account roots dry weight. Then, V. zizanioides grass potential
for the unpredictable variables present in natural in HM removal from soil was analyzed. Finally, the
settings. 46,47 These factors include soil type, climatic impact of V. zizanioides grass and Cd-contamination
conditions, and the interaction of plant species with on the microbial structure of soil was studied by NGS.
the environment, which can significantly affect the The results proved that HM contamination destroys
efficiency of HM removal. Furthermore, the presence the soil biodiversity. Planting V. zizanioides enriches
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in the soil of different species of the same HM, like in the soil microbiome and helps to reduce the negative
the case of As, might reduce the ability of the plants due impacts of contaminants on the microorganisms. In
to the toxicity of the different species. Therefore, for conclusion, the combination uses of phytoremediation
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a comprehensive understanding of phytoremediation and bioremediation (stimulation of the native
potential, it is essential to conduct field trials that microorganisms) provides a more efficient approach to
incorporate these natural variables. addressing soil contamination. Although analyzing the
The management of Cd-contaminated plants and soil, physicochemical properties and elemental content of the
particularly regarding root disposal and the prevention soil after the experiment would have provided valuable
of soil re-contamination, have been reviewed and insights, we recommend that future studies include this
explained by several scientific sources and studies, as aspect to gain a more comprehensive understanding of
follows: the phytoremediation process.

Volume 22 Issue 2 (2025) 39 doi: 10.36922/AJWEP025040021