Study on the Effect of pH on Rhizosphere Soil Fertility and the Aroma Quality of Tea Trees and Their Interactions

Round 1

Reviewer 1 Report

The paper deals with the issue important in the production of tea trees, which indicates a somewhat local nature of the research, and thus limited interest in this topic. Regardless of this, the relationship between the pH of the rhizosphere and soil fertility as well as the quality and quantity of aromatic compounds in tea may be an important aspect for tea producers. Therefore, the research should be considered important and interesting. The paper was developed in the correct way, in accordance with the rules of writing scientific papers. Regardless of this, the authors did not avoid some imperfections. Below are my comments that should be considered and included in the new version of the work:
1. Summary: sentences in line: 11-12 are unclear - need to be reworded
2. Keywords: keywords duplicate those found in the title of the work - this should not be the case, it should be changed.
3. oolong tea notation - should be standardized (see lines 41 and 43)
4. Introduction - should be extended with the importance and influence of pH on soil properties and plant quality
5. Lack of clearly defined research hypotheses and goals of the work - it is necessary to supplement and adequately lead the discussion and formulate conclusions
6. in subchapter 2.1, the systematics of soils, the depth and the method of collecting soil samples should be provided. Description in lines 84 - 88 unclear - it should be corrected.
7. please use the generally used term - organic matter - OM in place of the strange abbreviation - OMC
8. The information under table 1 should be included in the Material and Methods chapter with appropriate comments
9. The quality of Figures 1, 3, 4 should be improved
10. Section 3.5 contains repeated thoughts from the previous ones (see lines: 323-329, 341-350). I believe that the text contained in this subchapter can be rewritten and merged with the earlier one.
11. Conclusions should be edited accordingly to the research hypotheses, so that they do not constitute repeated research results, but proper conclusions

Author Response

The paper deals with the issue important in the production of tea trees, which indicates a somewhat local nature of the research, and thus limited interest in this topic. Regardless of this, the relationship between the pH of the rhizosphere and soil fertility as well as the quality and quantity of aromatic compounds in tea may be an important aspect for tea producers. Therefore, the research should be considered important and interesting. The paper was developed in the correct way, in accordance with the rules of writing scientific papers. Regardless of this, the authors did not avoid some imperfections. Below are my comments that should be considered and included in the new version of the work:

1. Summary: sentences in line: 11-12 are unclear - need to be reworded

A: Thank you to the reviewers. The authors have revised it.

2. Keywords: keywords duplicate those found in the title of the work - this should not be the case, it should be changed.

A: Thank you to the reviewers. The authors have revised it.

3. oolong tea notation - should be standardized (see lines 41 and 43)

A: Thank you to the reviewers. The authors have revised it.

4. Introduction - should be extended with the importance and influence of pH on soil properties and plant quality

A: Thank you to the reviewers. The authors have made appropriate additions to the Introduction and highlighted them in red.

5. Lack of clearly defined research hypotheses and goals of the work - it is necessary to supplement and adequately lead the discussion and formulate conclusions

A: Thank you to the reviewers. The authors have revised the full text and hope that it meets the requirements.

6. in subchapter 2.1, the systematics of soils, the depth and the method of collecting soil samples should be provided. Description in lines 84 - 88 unclear - it should be corrected. 
   A: Thank you to the reviewers. The systematic classification of soils with different degrees of acidification is not clearly defined. The authors have revised the Materials and Methods to express it as soils with different pH values. For sampling of soils, etc., the authors revised and described the experimental design in detail in Materials and Methods.

7. please use the generally used term - organic matter - OM in place of the strange abbreviation – OMC

A: Thank you to the reviewers. The authors have made changes in the article as well as revised the text in the graph.

8. The information under table 1 should be included in the Material and Methods chapter with appropriate comments

A: Thanks to the reviewers. The authors have explained the method of determination of each index in Materials and Methods, and also provided the method of conversion of fertility indexes and supplementary materials.

9. The quality of Figures 1, 3, 4 should be improved

A: Thanks to the reviewer . The authors have revised the graphs and hopefully they will meet the requirements.

10. Section 3.5 contains repeated thoughts from the previous ones (see lines: 323-329, 341-350). I believe that the text contained in this subchapter can be rewritten and merged with the earlier one.
    A: Thank you to the reviewer. The authors have rewrited and merged the contents of the two sections in accordance with the suggestions of the reviewers.

11. Conclusions should be edited accordingly to the research hypotheses, so that they do not constitute repeated research results, but proper conclusions

A: Thank you to the reviewer. The authors have reorganized the conclusions and hopefully they will meet the requirements.

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

 

Title: Study on the effect of pH on rhizosphere soil fertility and aroma quality of tea trees and their interactions

Dear Authors

 

The  manuscript is very interesting and fall within the scope of the journal. The experimental dataset undoubtedly are useful and constitutes scientific values. The presented manuscript deals with the current local problem.  The aim of this study was effects of soil acidification on the rhizosphere soil fertiluty and tea aroma quality were analyzed. In order to increase the usefulness of the article, Authors must refer to the following points.

1.      Abstract: The name of the statistical method according to which the long-term field experiment was conducted should be added. Add fertilizer objects. How many replications were there?

2.      Introduction: Line 29 – Geographical coordinates must be entered correctly.

3.      Materials and Methods: Subection 2.1. – The years of cultivation of tea trees, the area of the field experiment, the number of fertilizing objects, the fertilization used, the number of repetitions, the type of soil according to the WRB, the number of soil samples taken and the depth of soil sampling, how many tea trees were collected leaves and buds should be completed. Line 95 – there should be:…organic matter content…..

4.      Results and Discussion: This section has been well presented. Figure 1 and 3 – The description of Figure 1 and 3 (font size and color intensity) should be improved. Table 1 – All units should be corrected according to editorial requirements. Line 312 – there should be: Organic matter content; CEC: Cation exchange capacity;…..Figure 4. Note:….. there should be: Organic matter content; CEC: Cation exchange capacity;…..

5.      Conclusions: Conclusions must be redrafted. At the end of the conclusions, based on the research, optimal soil parameters for the production of the best quality tea should be proposed. The authors should propose directions for future research on plantations of tea tree cultivation.

6.      References: DOI numbers need to be added. Item 15 - Gholoubi et al. - not cited in the text of the manuscript.

 

Best regards

Minor editing of English language required

Author Response

Title: Study on the effect of pH on rhizosphere soil fertility and aroma quality of tea trees and their interactions
Dear Authors

 The  manuscript is very interesting and fall within the scope of the journal. The experimental dataset undoubtedly are useful and constitutes scientific values. The presented manuscript deals with the current local problem.  The aim of this study was effects of soil acidification on the rhizosphere soil fertiluty and tea aroma quality were analyzed. In order to increase the usefulness of the article, Authors must refer to the following points.

1. Abstract: The name of the statistical method according to which the long-term field experiment was conducted should be added. Add fertilizer objects. How many replications were there?

A: Thank you to the reviewer. The authors have made appropriate additions to the Abstract, including the specific number of replications and statistical methods, as well as the authors' description in Materials and Methods. Thanks.

2. Introduction: Line 29 – Geographical coordinates must be entered correctly.

A: Thank you to the reviewer. The authors provided geographic coordinates in the Introduction, Materials and Methods, so the authors deleted the geographic coordinates in the Introduction and retained the geographic coordinates in Materials and Methods.

3. Materials and Methods: Subection 2.1. – The years of cultivation of tea trees, the area of the field experiment, the number of fertilizing objects, the fertilization used, the number of repetitions, the type of soil according to the WRB, the number of soil samples taken and the depth of soil sampling, how many tea trees were collected leaves and buds should be completed. Line 95 – there should be:…organic matter content…..

A: Thank you to the reviewer. The authors have reorganized the Materials and Methods and improved the information.

4. Results and Discussion: This section has been well presented. Figure 1 and 3 – The description of Figure 1 and 3 (font size and color intensity) should be improved. Table 1 – All units should be corrected according to editorial requirements. Line 312 – there should be: Organic matter content; CEC: Cation exchange capacity;…..Figure 4. Note:….. there should be: Organic matter content; CEC: Cation exchange capacity;…..

A: Thanks to the reviewer . The authors have corrected Figures 1 and 3, as well as the incorrect words. Thank you very much .

5. Conclusions: Conclusions must be redrafted. At the end of the conclusions, based on the research, optimal soil parameters for the production of the best quality tea should be proposed. The authors should propose directions for future research on plantations of tea tree cultivation.

A: Thank you to the reviewer. The authors have reorganized the conclusions and hopefully they will meet the requirements.

6. References: DOI numbers need to be added. Item 15 - Gholoubi et al. - not cited in the text of the manuscript.

A: Thank you to the reviewer. The authors have added and also revised the references.

Reviewer 3 Report

Review comments on the manuscript entitled "Study on the effect of pH on rhizosphere soil fertility and aroma quality of tea trees and their interactions":

- The topic of the article is interesting and practical. The way the results are presented in graphs is attractive and innovative. However, with the following comments the manuscript may be improved.

1) Materials & Methods section: What experimental design is used in this study? What kind of means comparison test was used to compare the means (LSD, Tukey, Duncan, or ...)?

2) In 3.1. section (Effect of Soil pH Value on Soil Fertility): In your opinion, what could be the reasons for improving OC, CEC, and available forms of N, P, and K with increasing pH? The relevant reasons can be better explained according to the soil reaction.

3) In section 3.2: Is there a biochemical relationship between aroma and pH changes? For example, the effect of pH on the biosynthesis pathways of terpenoids may be explained in more detail, with the help of relevant references.

4) Subtitle 3.3 (Effect of soil pH on odor activity value (OAV) of key compounds in tea leaves) is placed inside the caption of Figure 1. Please move it into the text.

5) Line 219: The sentence "And the odor ..." has started with the word "And", please correct it.

6) Line 264: The word "floral" is repeated twice.  Instead of the latter, the word "burnt" should be replaced.

7) Directing the discussion towards the biosynthetic pathway of geraniol can enrich the discussion.

English writing needs minor revision and corrections.

Author Response

Comments and Suggestions for Authors

Review comments on the manuscript entitled "Study on the effect of pH on rhizosphere soil fertility and aroma quality of tea trees and their interactions":

- The topic of the article is interesting and practical. The way the results are presented in graphs is attractive and innovative. However, with the following comments the manuscript may be improved.

1) Materials & Methods section: What experimental design is used in this study? What kind of means comparison test was used to compare the means (LSD, Tukey, Duncan, or ...)?

A: Thank you to the reviewer. The authors have refined the experimental methods and added statistical methods for the data.

2) In 3.1. section (Effect of Soil pH Value on Soil Fertility): In your opinion, what could be the reasons for improving OC, CEC, and available forms of N, P, and K with increasing pH? The relevant reasons can be better explained according to the soil reaction.

A: Thank you to the reviewer. The authors have added some discussion to the text and highlighted it in red.

3) In section 3.2: Is there a biochemical relationship between aroma and pH changes? For example, the effect of pH on the biosynthesis pathways of terpenoids may be explained in more detail, with the help of relevant references.

A: Thank you to the reviewer. The authors have added discussion to the text and highlighted it in red.

4) Subtitle 3.3 (Effect of soil pH on odor activity value (OAV) of key compounds in tea leaves) is placed inside the caption of Figure 1. Please move it into the text.

A: Thank you to the reviewer. The authors have adjusted.

5) Line 219: The sentence "And the odor ..." has started with the word "And", please correct it.

A: Thank you to the reviewer. The authors have revised it.

6) Line 264: The word "floral" is repeated twice.  Instead of the latter, the word "burnt" should be replaced.

A: Thank you to the reviewer. The authors have revised it.

7) Directing the discussion towards the biosynthetic pathway of geraniol can enrich the discussion.

A: Thank you to the reviewers. The authors have added some discussion of the synthetic pathway of geraniol and cited relevant references.

Reviewer 4 Report

This research project sampled rhizosphere soil to analyze for soil fertility and tea tree leaves to analyze for aroma / volatile compounds. Available nutrients altered with soil pH but total nutrients did not change with pH. Floral mainly come from geraniol and the floral aroma dominated the aroma for high quality tea leaves. The manuscript is generally well written but is lacking some key detail that could improve the understanding of the research. I’ve outlined the major comments bellow followed by the line-by-line comments.

 

General comments:

·        For the in text citation, I believe you need to put the year in parentheses.

·        More information in the introduction on why the rhizosphere soil characteristics are important in general then tailor it to there is limited information on tea tree and rhizosphere soil. This would round out the introduction on why rhizosphere soil was specifically used versus bulk soil.  

·        At the end of the conclusion section, there is no “so what does this research mean.” So we know pH alters the nutrient availability and aroma of tea tree leaves. Is there a pH rage that will produce subpar tea and not go to market? Is there a range that the highest grade of tea can come from? How does this alter what the grower of tea trees will do?

Line-by-line comments:

Line 42: “famous tea tree” how is this relevant and is there a citation to back up this is a famous or well-known plant of the area?

Line 46: Is aroma used only during research to evaluate the quality to tea leaves or is it also used for general production to evaluate the quality of their crop?

Line 97: the c in content should be lower case.

Line 109: it should state, “heated in a 50°C hot water bath…”

Line 153 and 162: Only chemical properties were measured in this experiment, not physical properties such as bulk density, water content, Ksat, etc..

Line 300: wasn’t geraniol and ionone also a major contributor to the volatile compounds for this soil pH (P3)? Similarly, wasn’t cyclocitral also a major contributing volatile compound for P4? Explain why these major compounds are not listed here for the overall odor characteristics.

Line 308-Figure 3: the yellow color is hard to read. Please change the color to a darker one.

Line 344 and 345: Only soil chemical properties were measured in this experiment.

Line 354: all the abbreviations in this conclusions paragraph have been defined earlier in this manuscript.

Line 362: Only soil chemical properties were measured in this manuscript.

The English is generally well written, but there are some tense errors and run-on sentences that make it difficult to read in certain section. Try working with smaller sentences. Present tense can be used to general problems the tea tree farming operations face today (Example - this first sentence of the abstract). 

Author Response

Comments and Suggestions for Authors

This research project sampled rhizosphere soil to analyze for soil fertility and tea tree leaves to analyze for aroma / volatile compounds. Available nutrients altered with soil pH but total nutrients did not change with pH. Floral mainly come from geraniol and the floral aroma dominated the aroma for high quality tea leaves. The manuscript is generally well written but is lacking some key detail that could improve the understanding of the research. I’ve outlined the major comments bellow followed by the line-by-line comments.

 

General comments:

• For the in text citation, I believe you need to put the year in parentheses.

A: Thank you to the reviewers . The authors will follow up with revisions according to the journal's requirements. Thank you very much.

• More information in the introduction on why the rhizosphere soil characteristics are important in general then tailor it to there is limited information on tea tree and rhizosphere soil. This would round out the introduction on why rhizosphere soil was specifically used versus bulk soil.  

A: Thank you to the reviewers . The authors have made appropriate additions to the Introduction and hope that it meets the requirements.

• At the end of the conclusion section, there is no “so what does this research mean.” So we know pH alters the nutrient availability and aroma of tea tree leaves. Is there a pH rage that will produce subpar tea and not go to market? Is there a range that the highest grade of tea can come from? How does this alter what the grower of tea trees will do?

A: Thank you to the reviewers. The authors have revised the Conclusions and hope that they meet the requirements.

Line-by-line comments:

Line 42: “famous tea tree” how is this relevant and is there a citation to back up this is a famous or well-known plant of the area?

A: Thank you to the reviewer. The authors have added references.

Line 46: Is aroma used only during research to evaluate the quality to tea leaves or is it also used for general production to evaluate the quality of their crop?

A: Thank you to the reviewer. Aroma can be used to evaluate the quality of finished tea and also the quality of tea tree leaves. Aroma is often used to evaluate the quality of semi-finished and finished tea in the study of tea processing. In the planting process, the aroma of fresh leaves of tea tree is used to evaluate the quality of raw materials used to produce finished tea.

Line 97: the c in content should be lower case.

A: Thank you to the reviewer. The authors have revised it.

Line 109: it should state, “heated in a 50°C hot water bath…”

A: Thank you to the reviewer. The authors have revised it.

Line 153 and 162: Only chemical properties were measured in this experiment, not physical properties such as bulk density, water content, Ksat, etc..

A: Thank you to the reviewer. The authors have revised it to "Soil basic chemical indexes of different samples".

Line 300: wasn’t geraniol and ionone also a major contributor to the volatile compounds for this soil pH (P3)? Similarly, wasn’t cyclocitral also a major contributing volatile compound for P4? Explain why these major compounds are not listed here for the overall odor characteristics.

A: Thank you to the reviewer. First, for the floral aroma in P1, P2, P3, and P4, the contribution of geraniol amounted to 82.91%, 83.70%, 87.69%, and 88.51%, respectively. Second, for the overall aroma of P1, P2, P3, and P4, geraniol's contribution rate amounted to 65.74%, 71.05%, 74.97%, and 77.20%, respectively. Thus, the authors have proposed that geraniol is the main contributor to the floral aroma and also to the odor characteristics. In addition, the odor characteristics of the different compounds are detailed by the authors in the annexed material (Tables S3-S6).

Line 308-Figure 3: the yellow color is hard to read. Please change the color to a darker one.

A: Thank you to the reviewer. The authors have revised Figure 3.

Line 344 and 345: Only soil chemical properties were measured in this experiment.

A: Thank you to the reviewer. The authors have corrected all the changes to "soil chemical indexes".

Line 354: all the abbreviations in this conclusions paragraph have been defined earlier in this manuscript.

A: Thank you to the reviewer. The authors have revised the full text.

Line 362: Only soil chemical properties were measured in this manuscript.

A: Thank you to the reviewer. The authors have corrected all the changes to "soil chemical indexes".

Round 2

Reviewer 3 Report

The manuscript in its current form can be accepted.

Author Response

Comments and Suggestions for Authors

The manuscript in its current form can be accepted.

A: Thanks to the reviewers.

Reviewer 4 Report

This manuscript has gone through major revisions. The methods section and results and discussion section have a great more detail and are more comprehensive. The discussion portion now includes more information on the importance of soil pH relative to the tea tree that helps put the results into context. I’ve outlined a few comments below.

Pages number got out of order starting at the top of page 6 - it starts at 181. I’ve included the page number below to help in the comments.

Line 299 (page 3): What is this previously established method? Is this a new citation or are you referencing the GC-MS method? Please be more specific.

Line439-446 (page 4): Can you please email in text. I know the information is under Table 1, but it would be helpful to have this information in text.

Line 202-204 (page 6): Put the pH numbers in parentheses next to the percentages.

Line 214-218 (page 6): This is a run on sentence. Please break it up into 2 sentences.

Line 91-93 (page 13): Sentence doesn’t make sense, “however, not the lower pH value, the better, the appropriate pH value to help the transformation of soil nutrients, and soil fertility, and thus protect the quality of tea.” Are you trying to say the plant naturally makes the soil acidic, but it produces the highest quality of tea leaves at a pH of about 5?

I would end the conclusion section with a statement about why it is important to have a higher pH. Something like, optimizing soil pH for oolong tea tree is important for producing the highest quality of tea, which has economic benefits (more money) for farmers.

English is overall easy to follow. There are a few run on sentences and grammatical errors (but it doesn't take away from the content). 

Author Response

Comments and Suggestions for Authors

This manuscript has gone through major revisions. The methods section and results and discussion section have a great more detail and are more comprehensive. The discussion portion now includes more information on the importance of soil pH relative to the tea tree that helps put the results into context. I’ve outlined a few comments below.

Pages number got out of order starting at the top of page 6 - it starts at 181. I’ve included the page number below to help in the comments.

A: Thanks to the reviewers. The authors have revised it. It may be a Word version problem, the line number will be confused. The author also converted a PDF version to submit.

Line 299 (page 3): What is this previously established method? Is this a new citation or are you referencing the GC-MS method? Please be more specific.

A: Thanks to the reviewer. This was a method previously established by the authors and the reference was omitted. The authors have added it (Wang et al., 2023). Thank you very much.

Line439-446 (page 4): Can you please email in text. I know the information is under Table 1, but it would be helpful to have this information in text.

A: Thanks to the reviewers. The authors had previously misunderstood the reviewer. The author has made appropriate additions to the text and highlighted them in red.

Line 202-204 (page 6): Put the pH numbers in parentheses next to the percentages.

A: Thanks to the reviewers. The authors have added.

Line 214-218 (page 6): This is a run on sentence. Please break it up into 2 sentences.

A: Thanks to the reviewers. The authors have revised it.

Line 91-93 (page 13): Sentence doesn’t make sense, “however, not the lower pH value, the better, the appropriate pH value to help the transformation of soil nutrients, and soil fertility, and thus protect the quality of tea.” Are you trying to say the plant naturally makes the soil acidic, but it produces the highest quality of tea leaves at a pH of about 5?

 A: Thanks to the reviewers. The point the authors are trying to make here is that although the tea tree is an acidophilic plant, it is not the case that the lower the soil pH, the better, but rather that it is most beneficial to improve the quality of the tea leaves at the right pH, especially when the pH is around 5. (Tea tree is an  plant, however, not the lower the pH value, the better, the appropriate pH value to help the transformation of soil nutrients, and soil fertility, and thus improve the quality of tea.)

I would end the conclusion section with a statement about why it is important to have a higher pH. Something like, optimizing soil pH for oolong tea tree is important for producing the highest quality of tea, which has economic benefits (more money) for farmers.

A: Thanks to the reviewers. The authors have added.