Alleviating Cd Stress in Sunflower (Helianthus annuus) through the Sodium Silicate Application
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript reports on the potential of silicate soil amendment on the remediation of Cd by sunflower plants. The introduction briefly introduces the mechanism of Si in reducing the toxicity of heavy metals, i.e., via chemical reactions in the soil (L74-77). The stimulating effect of Si to elevate the plant’s resistance towards external stress is not presented until section 4.3 (L487). This structure makes certain claims in the middle sections confusing. For example, L186-888 suggests that Si “strengthened the tolerance of plants to Cd”. But this could be due to the less availability of Cd in the soil. In other words, with Si, the plants are exposed to less Cd, and the stress is less. This does not mean the tolerance of the plant becomes higher.
The second major problem is with the writing. There are too many confusing long sentences. The authors tend to present or compare several things in one long sentence. But very often it is very confusing. A few quick examples are L194-202, L242-246, L248-252, L257-262, L288-296, etc. Please recheck the whole manuscript, but not limited to the few indicated sentences, and make sure the content is presented correctly and understandably.
The following are a few specific comments.
1. Resolution of the graphical abstract is too low.
2. L59-62. Any literature information on the distribution of heavy metals in sunflower plants? Specifically, how likely can they accumulate in the edible seeds? The indication of “edible cash crop” makes it sound like the sunflower plants will be used to accumulate Cd, and later the seed will be harvested for eating and cash purposes. But the plants in this manuscript are only until the blooming stage. Please indicate the reason.
3. L75-77. Can this also be the mechanism for Cd, i.e., decreasing Cd uptake in the presence of Si? Is there any literature about the uptake of Cd in the presence of Si, e.g., for the listed few plants L78-82?
4. L135-136. Revise the first “belowground”. Is this how the Cd accumulation in Fig 2d-f calculated? They do not seem consistent.
5. L224 and Fig 2. Fig c and d are not consistent with the description at the caption. Please recheck.
6. L234. “p>0.05”? There are several such mistakes where no significant difference is denoted as p<0.05 (e.g., L236, L273, etc.).
7. L309. Figure 3e.
8. L438-441. The authors use data in Fig 2 to claim that Si treatment prevents migration of Cd from root to the aboveground parts. However, without Si treatment, Cd can still accumulate more at the plant root (the Si0 series in Fig 2). The data do not support the claim.
Comments on the Quality of English LanguageToo many long confusing sentences.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe relevance and importance of the research presented by the authors of this article is beyond doubt.
A few points:
1. In my opinion, the title of the article does not fully reflect the results presented. The title mentions “Improving the Cd-contaminated soil remediation..”, however, the authors presented only data on the accumulation/content of Cd in sunflower, but no data on the Cd loss in the soil. Either the article title needs to be corrected, or the extremely missing data on the Cd loss in soil must be provided.
2. In the experiment there is no control variant with the original soil (without the addition of Cd)! This variant is a must have!
3. In table 2 it is necessary to clarify the content of Cd and Si per kg of which soil (dry weight soil?)
4. In Fig. 2 a, b, c, it is also necessary to clarify the units of measurement (mg/kg of what dry weight plant, root, stem, leaf?)
5. Fig. 2 d, e, f units of measurement are also unclear, decipher them.
6. Line 500-502 - Are there other mechanisms known to increase the strength and stability of cell membranes in plants when adding Cd, in addition to increasing the activity of antioxidant enzymes and reducing ROS levels. If yes, describe in more detail, it will greatly enrich the article.
7. The authors report that with this phytoremediation method, Cd accumulates in sunflower. Another question arises about the disposal of environmentally unsafe plants. The authors write nothing about this.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsDear authors,
The manuscript with the ID sustainability-286291, titled "Enhancing the remediation of Cd-contaminated soil and reducing Cd stress in sunflower (Helianthus annuus L.) through the use of sodium silicate", presents the findings of an experiment on using exogenous Si for phytoremediation of Cd in soil.
The paper is well written and the results are presented in the context of literature data.
Upon thorough examination of the writing and chemical formulas, the work can be considered suitable for publishing in its current state.
Good luck!
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsSustainability – 2862911
The main question addressed by this research is the exogenous effects of silicon (Si) on the phytoremediation of sunflower, particularly in Cd-contaminated soil in China. The study investigates changes in growth rate, photosynthesis, and the concentration of antioxidant enzymes in sunflowers under different concentrations of Si application. The novelty lies in examining the synergistic effect of phytoremediation by sunflowers with exogenous Si application, an area that has been relatively unexplored despite extensive research on phytoremediation.
Major comment:
1. The results presented in relation to objective 1, which pertains to the growth process of sunflowers and their ability to remove Cd, are clear. However, information regarding objective 2, which focuses on the detoxification mechanisms occurring in sunflowers, is lacking. Rather than elucidating detoxification mechanisms, the data primarily demonstrate the mitigating effect of Si on Cd stress. Further detailed analysis is necessary to support claims about detoxification mechanisms.
2. How do you define the ‘biomass’ in this study? The taller the sunflower, the weightier the sunflower in dry weight. So, I think the dry weight of sample in same size of specimen (for example, per cm of stem_) is required to see the increase of ‘biomasses.
3. Are there any potential risks of Cd release into the soil, particularly due to high Cd concentration in roots.
Minor comment:
2. The duration of the phytoremediation process should be specified.
4. Explanation of the rationale behind the chosen concentrations of Si application (ranging from 0 to 1500 ppm) is necessary.
5. Information about soil moisture content should be provided.
6. Estimation of Cd balance, including remaining Cd, uptake, transpiration, and removal rate, should be included.
7. Detailed description of cultivation methods, including watering procedures during the experiment, is needed.
8. Figures should be provided in higher resolution, and any missing figures or tables (such as Figure 3 (f) or (g)) should be addressed.
9. Table 1 lacks explanations about the characters associated with each number (e.g., 40.53... cA).
Thorough English check:
Typos (Table 1) and redundancies, etc. should be corrected.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsNA.
Author Response
Once again, thank you very much for your comments and suggestions.
Reviewer 2 Report
Comments and Suggestions for AuthorsPerhaps this article title would be better: Alleviating Cd stress in sunflower (Helianthus annuus L.) through the sodium silicate application
As recommendations for the authors: In your subsequent experimental work, you need to take a more careful approach to experiment planning and be sure to take into account the control option
Author Response
我们衷心感谢审稿人的仔细阅读。正如审稿人所建议的那样，我们已将“硅酸钠通过促进向日葵（向日葵）的发育、生理学和抗氧化酶活性来缓解镉胁迫”更正为“向日葵（向日葵）的缓解镉胁迫”。 通过硅酸钠应用”。P1，第 2-6 行。
在未来的实验工作中，我和我的团队将更仔细地计划我们的实验，以确保将控制选项考虑在内。
再次非常感谢您的意见和建议。
Reviewer 4 Report
Comments and Suggestions for AuthorsThank you for your sincere response.
Author Response
Once again, thank you very much for your comments and suggestions.
