Foliar Mn and Zn Treatments Improve Apple Tree Nutrition and Help to Maintain Favorable Soil pH

Round 1

Reviewer 1 Report

I find your work very remarkable, but there have been huge mistakes and deficiencies in your writing.

Corrections that need to be made are presented in detail below.

1)      The writing order of the sections in the article should be as follows.

Introduction>Materials and Methods>Results>Discussion>Conclusions

But I guess this article was written in the following by mistake

Introduction>Results>Discussion>Materials and Methods>Conclusions

2)      An abbreviation such as "417 tr ha^-1" or any abbreviation must be clearly written for once in the first place in the manuscript. (417 trees ha^-1)

3)      Table 2 presents the available plant nutrients in the soil. How, where and by which method (ICP or or any other method) the soil analysis is done should be written briefly in the text.

4)      Line 307-309 could not understood. This lines should write more clearly.

“We sample leaves in the spraying day about 1 hour before foliar fertilizing. Usually, we sampled leaves before the spraying, so the analyzes result from the day of the first treatment show start leaf manganese contents” (in the manuscript)

5)      Some results of the research were associated with the weather condition, but no citaitons were shared to prove this. If the weather is not as claimed, the associations will be wrong.

6)      Some of the results were shared in the Discussion section. According to the template, the discussion section should be as follows.

“4. Discussion

Authors should discuss the results and how they can be interpreted from the per-spective of previous studies and of the working hypotheses. The findings and their impli-cations should be discussed in the broadest context possible. Future research directions may also be highlighted.”

7)      In addition, references 2, 5 and 17 cannot be reached. References 6 and 16 were prepared in 6 and 16 Russian languages. It is not known whether the documents on the website were prepared by following any academic process. International article, proceeding and book etc. references should be added instead of removing them from the article.

8)      In the references section,

a)       the DOI information of any reference is not shared. The following information is available in the template:

“Include the digital object identifier (DOI) for all references where available”

b)      “Title of the article” is  it is sentence order. that is, the first letter of the article name should be capitalized and the other letters should be lowercase. (Template)

Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range. (Template)

c)       Punctuation should not be used after “Abbreviated Journal Name” but most references used "dot"

9)       The following sentence should be added at the bottom of the article:

“Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.”

Comments for author File: Comments.pdf

Minor editing of English language required

Author Response

Authors would like to thank Reviewer for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript.

1) Reviewer 1: The writing order of the sections in the article should be as follows.

Introduction>Materials and Methods>Results>Discussion>Conclusions

But I guess this article was written in the following by mistake

Introduction>Results>Discussion>Materials and Methods>Conclusions

Response: We agree with the remark of respected reviewer and moved sections according to the order Introduction>Materials and Methods>Results>Discussion>Conclusions

2) Reviewer 1: An abbreviation such as "417 tr ha^-1" or any abbreviation must be clearly written for once in the first place in the manuscript. (417 trees ha^-1)

Responce: We clarify these abbreviation in the first place in the manuscript (Line 15).

3) Reviewer 1: Table 2 presents the available plant nutrients in the soil. How, where and by which method (ICP or or any other method) the soil analysis is done should be written briefly in the text.

Response: We added the next information to the text of the manuscript: “The soil analyses were done in the agrochemical laboratory of I.V. Michurin Federal Scientific Centre.” and “The soil was analyzed to determine the content of nitrogen (by Kjeldahl), phosphorus (extracton with 0,5N CH3COOH followed by phosphomolybdenum blue method and SnCl2 staining and detecting at 750 nm), total exchangeable potassium was assyed by a flame photometer, exchangeable soil calcium was determined by complexometric method (titration of calcium with Trilon B at pH 12.5-13.0 using murexide as an indicator.” (Lines 168-174).

4) Reviewer 1: Line 307-309 could not understood. This lines should write more clearly.

“We sample leaves in the spraying day about 1 hour before foliar fertilizing. Usually, we sampled leaves before the spraying, so the analyzes result from the day of the first treatment show start leaf manganese contents” (in the manuscript)

Response: We edited sentences in the lines (156-161): “Leaf samples were taken from the middle of annual shoots from the mid-height of canopies. We sampled 4 leaves per tree in the middle of the canopy from the mid of annual shoots from 8 random trees from each side. Subsequently, we selected 32 leaf sub-samples for each replica constituting a pooled sample which was used for analyses. The leaves were also sampled 1 hour before spraying to provide a baseline for the assessment of the foliar fertilization effect”.

5) Reviewer 1: Some results of the research were associated with the weather condition, but no citations were shared to prove this. If the weather is not as claimed, the associations will be wrong.

Response: We edited sentences in the lines (314-315): “Drought is one of the a major abiotic stress factors that adversely effects crop productivity, causing a reduction in fruit yield [43]. Cv. Bogatyr was selected in 1926 but began to be plant in the orchards since 1972 [44]. This cultivar has relatively high frost resistance but weak drought resistance.”

Lines (364-370) “In 2022, we noted the highest leaf manganese contents. In this year the precipitation amount during studied period was 515.9 mm, which was largest during our experimental years (2020 – 242.7 mm; 2021 – 325.5 mm). Earlier, Sud et al. [55] reported that the value of manganese in green tea shoot had a significant positive correlation with accumulative rainfall. “ 

Lines (334-336): “The weather, in particular, relative humidity, could strongly affect the permeability of cuticle for ions (the increase in humidity from 50% to saturation also increase in permeability.     

6) Reviewer 1: Some of the results were shared in the Discussion section. According to the template, the discussion section should be as follows.

“4. Discussion

Authors should discuss the results and how they can be interpreted from the per-spective of previous studies and of the working hypotheses. The findings and their impli-cations should be discussed in the broadest context possible. Future research directions may also be highlighted.”

Response: We moved Figures with scatter plots to the Result section.

7) Reviewer 1: In addition, references 2, 5 and 17 cannot be reached. References 6 and 16 were prepared in 6 and 16 Russian languages. It is not known whether the documents on the website were prepared by following any academic process. International article, proceeding and book etc. references should be added instead of removing them from the article.

Response: Reference 2 could be reached. In the attached screenshots there are two versions (small scale 30% and large scale 100%). The source was accessed 02.09.2023.

Reference 5 was also accessed 02.09.2023. The screenshot_3 was done to confirm this, also this information is available to download (attached pdf-file).

Reference 6 is in English language (screenshot_4).

We add the next information (Lines 64-65) “the main part of the root system is in the soil layer 0.2-0.8 m deep and 1.0-1.5 m around”.

We agreed with the remark of respected reviewer about academic process concerning sources 16 and 17 and replaced them with the scientific works of Michurinsk scientists where the rootstock B118 was bred and well studied. These papers are only in Russian language. One these work with description of B118 made by the author of this rootstock Prof, V.I. Budagovskii (B-series) :

Budagovskii, V.I. Cultivation of low-vigorous fruit trees. Kolos: Moscow, Soviet Union, 1976; 304 p. (in Russian)

Suvorov N.N. Evaluation of promising hybrid forms of low-vigorous apple clonal rootstocks. Candidate of Science (Agric),  Michurinsk State Agrarian University, Michurinsk, Russia, 12.04.2001. (in Russian)

8) In the references section,

1. a)Reviewer 1: the DOI information of any reference is not shared. The following information is available in the template:

“Include the digital object identifier (DOI) for all references where available”

Response: We included the DOI information where available.

1. b) Reviewer 1: “Title of the article” is it is sentence order. that is, the first letter of the article name should be capitalized and the other letters should be lowercase. (Template)

Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range. (Template)

Response: We changed the capitalization of letters in the title of the articles according to template. 

1. c)Reviewer 1: Punctuation should not be used after “Abbreviated Journal Name” but most references used "dot"

Response: the template indication “Abbreviated Journal Name” is not real abbreviation. According to the grammar section of Oxford Dictionaries if the abbreviation consists only of the first part of a word, then you should put a full stop at the end: Wed. [= Wednesday], Dec. [= December]. We used dot in the abbreviated journal names according to grammatical rules in such cases.

9) Reviewer 1: The following sentence should be added at the bottom of the article:

“Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.”

Response: We added this sentence at the bottom of the article.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript entitled ‘Enhancement of N, P, K uptake by Mn and Zn foliar treatments in apple tree growing at optimal soil pH’ is a clear study of the effects of foliar spraying of Mn, Zn and other trace elements on the uptake of N, P, and K by apple trees under the conditions of suitable soil acidity and alkalinity. The results of this study have a guiding value for fertilization measures and management of traditional orchards and deserve further research. However, some of the content in the manuscript needs to be improved. Here are some specific comments:

1） Line2: The title states that it was under optimal soil pH conditions, however, did the experiments carried out in the text over a period of 3 years were under optimal soil pH conditions, it does not seem to have been;

2） Line20, Line254: Please use the correct representation of latitude and longitude (e.g. 50N, 40E);

3） Line43: Some abbreviations in the text should show the full name when they first appear to minimize confusion for the reader. For example, ‘eC values’ can be changed to ’electrical conductivity (EC) values’;

4） Line91: In Figure 1, please indicate the time in the horizontal coordinate in the form of '04.29' instead of '29.04', including the figures in the following text; In addition, please give the necessary annotations in the text as to what "d.m." stands for；

5） Lin272: I am confused about the period of foliar spraying in this section, and it is recommended to express it clearly in plain language.

6） Lin329: ’Single-element Mn sprayings showed a larger effect on foliar N than mixtures with other fertilizers.’ However, in the experiment, the treatment of T3 also contained Fe;

7） Overall, this study is greatly influenced by the external environment and is difficult to avoid. I have doubts about some of the data. However, in future research, I suggest increasing the number of sampling and measurements to reduce errors.

Author Response

Authors would like to thank Reviewer for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript.

1）Reviewer 2:  Line2: The title states that it was under optimal soil pH conditions, however, did the experiments carried out in the text over a period of 3 years were under optimal soil pH conditions, it does not seem to have been;

Response: We did not include soil pH as an artificially varying factor in our experimental design but monitored the actual soil pH and accepted the “optimal pH” as it is outlined in literature. By mentioning the optimal pH in the title of the article we would like to highlight that low and rare fertilizer application favorably affected the soil pH and enhanced the nutrient uptake. Still, we changed the article title to “Foliar Mn and Zn treatments improve apple tree nutrition and helps to maintain the favorable soil pH”

2）Reviewer 2: Line20, Line254: Please use the correct representation of latitude and longitude (e.g. 50N, 40E);

Response: We changed it to (52°36'57.1"N 40°17'04.1"E).

3）Reviewer 2: Line43: Some abbreviations in the text should show the full name when they first appear to minimize confusion for the reader. For example, ‘eC values’ can be changed to ’electrical conductivity (EC) values’;

Response: We expanded the abbreviations: “electrical conductivity”, “Budagovskii 118”, “Biologische Bundesanstalt, Bundessortenamt and Chemical industry”, “cultivar”.

4）Reviewer 2: Line91: In Figure 1, please indicate the time in the horizontal coordinate in the form of '04.29' instead of '29.04', including the figures in the following text; In addition, please give the necessary annotations in the text as to what "d.m." stands for；

Response: we changed the time designation according to the recommendation of the Reviewer and expanded the annotation, i.e. d.m. – dry matter in Figures 1, 3, and 5. 

5）Reviewer 2:  Lin272: I am confused about the period of foliar spraying in this section, and it is recommended to express it clearly in plain language.

Response: we changed the description of the treatments as follows: Development stage; Preparation, Active substance content, and the Application rate. Also, we indicated the day of spraying.

6）Reviewer 2:   Lin329: ’Single-element Mn sprayings showed a larger effect on foliar N than mixtures with other fertilizers.’ However, in the experiment, the treatment of T3 also contained Fe;

Response: We added the following clarification in the Results Section (Lines ...): “Starting from June, Fe preparations has been included in the T3 treatment. Taking into account the timing of foliar fertilizing, it is more likely that the overall effect of this treatment was caused by the Mn included in the sprayings from the very beginning.”

7）Reviewer 2:    Overall, this study is greatly influenced by the external environment and is difficult to avoid. I have doubts about some of the data. However, in future research, I suggest increasing the number of sampling and measurements to reduce errors.

Response: We agree with respected reviewer that the study is greatly influenced by weather and other external impacts. This problem is common for field studies in plant nutrition, it is also a source of contradictory results one can find in the literature. In our future research we will do our best to improve the experimental design to make it more robust.

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript entitled "Enhancement of N, P, K uptake by Mn and Zn foliar treatments in apple tree growing at optimal soil pH" focuses on the study of micronutrient uptake by foliar fertilization of apple trees. Although foliar fertilization is not a completely innovative topic, the article draw the reader's attention as the authors present the issue relating to the possible impact on soil and human health due to the intensive cultivation of apple orchards.

Before being considered for publication, the manuscript needs major revisions.

Title:

-It's too long and unclear. It is suggested to rewrite it. For example it could be "Effects of Mn and Zn foliar treatments on the Nutrition of Apple Trees".

Abstract: 

- It is suggested to rewrite it. The first part (lines 12-18) is too descriptive and not suitable for a section like this. It would be better to move it to the introduction. 

Introduction:

- Should be rewritten. There are many unrelated to each other  concepts and no reference is made to foliar fertilization. 

- The sentence in lines 40-43 is obvious and the bibliographic reference unclear. Furthermore, the sentence "recently this trend has changed, so the chemical fertilizer application rates are pushed down now" should also be clarified. 

-To improve the quality of the paper, the authors could include data relating to areas cultivated with intensive apple orchards in Russia and the rest of the world. 

- Finally, the objectives should also be improved and the phrase "this effect is thought to be mediated by upregulation of the plant metabolism [30, 31, 32]" should be eliminated.

Materials and methods:

- It is recommended to include a complete characterization of the experimental soils.

- Line 272-279: this part is unclear. This information could be reported in a table to make it easier for the reader's understanding.

- How many leaves were sampled from each tree?

Results:

- The presentation of results needs to be improved.

- Figures: Statistical analysis is missing. The letters relating to the significant differences are necessary to better understand the results and to make the paper publishable.

- Lines 83-86: the concepts repeat themselves.

Conclusions:

- It is necessary to rewrite this part because the results are presented again. Innovative solutions for apple producers to improve production should be included in this section.

References:

- They must be completely overhauled to improve the formatting. Some are not clear, others should be updated.

Minor comments:

- Keywords: they must be different from those of the title to give greater visibility to the manuscript;

- Line 40: delete sentence, it's obvious;

- Line 79: Delete "As stated above" (it's a new paragraph);

- Table 1: "42.1bb" is an error. Please correct;

- Review the English language.

English language needs to be improved

Author Response

Authors would like to thank Reviewer for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript.

Title:

1) Reviewer 3 -It's too long and unclear. It is suggested to rewrite it. For example it could be "Effects of Mn and Zn foliar treatments on the Nutrition of Apple Trees".

Response: We agree with the Reviewer’s suggestion. The title has been changed to “Foliar Mn and Zn treatments improve apple tree nutrition and helps to maintain the favorable soil pH”.

Abstract: 

2) Reviewer 3 - It is suggested to rewrite it. The first part (lines 12-18) is too descriptive and not suitable for a section like this. It would be better to move it to the introduction. 

Response: We agree with this suggestion, so we moved the first part of the abstract to the introduction and rewrote the rest of the abstract.

Introduction:

3) Reviewer 3 - Should be rewritten. There are many unrelated to each other concepts and no reference is made to foliar fertilization. 

Response: The main topic of the issue is “Precision Management Systems for Sustainable orchards and Vineyards The idea of “sustainable orchards” has several interpretations depending on the context (economic sustainability, environmental sustainability, etc.). This was the reason for invoking different concepts in the Introduction. We believe that the reader will need them to understand the differences, pro et contra of different orchard types. At the same time, we agree with respected Reviewer that the introduction should be enriched with references on foliar fertilization, it has been done in the revised version of the manuscript.

4) Reviewer 3 - The sentence in lines 40-43 is obvious and the bibliographic reference unclear. Furthermore, the sentence "recently this trend has changed, so the chemical fertilizer application rates are pushed down now" should also be clarified. 

Response: It is not entirely clear what the respected Reviewer meant “bibliographic reference unclear”: Gerry Nielsen is famous Canadian scientist in the field of fertilization and fertigation of delicious fruit trees worked at Pacific Agri-Food Research Centre (Summerland Research Station). One of the co-authors of this manuscript had the good fortune to meet this man personally at a conference in Bolzano (Italy) in 2017 and could be convinced of his high professionalism and erudition.

We edited the sentence “recently this trend has changed, so the chemical fertilizer application rates are pushed down now”: “Recently this trend to boost apple productivity by increasing the application of chemicals including fertilizer in high density orchards has changed to the opposite trend for reduction of the application of the chemicals to save the environment”.

5) Reviewer 3 - To improve the quality of the paper, the authors could include data relating to areas cultivated with intensive apple orchards in Russia and the rest of the world. 

Response: The comprehensive information about the areas cultivated in Russia and the rest of the world will be a lot of data which might be more pertinent for a review paper. Still, following the advice of the Reviewer 3, we added the required information in the amount which will not distort the structure of the manuscript.

6) Reviewer 3 - Finally, the objectives should also be improved and the phrase "this effect is thought to be mediated by upregulation of the plant metabolism [30, 31, 32]" should be eliminated.

Response: We have taken into account the remark of a respected Reviewer 3 and edited the objectives paragraph accordingly.

Materials and methods:

7) Reviewer 3 - It is recommended to include a complete characterization of the experimental soils.

Response: We included the soil profile description.

8) Reviewer 3 - Line 272-279: this part is unclear. This information could be reported in a table to make it easier for the reader's understanding.

Response: We reported the information about the foliar sprayings in a table and added the treatment dates.

9) Reviewer 3 - How many leaves were sampled from each tree?

Response: We sampled 4 leaves per tree in the middle of the canopy from the mid of annual shoots from 8 random trees. Subsequently, we selected 32 leaf sub-samples for each replica constituting a pooled sample which was used for the analyses.

Results:

10) Reviewer 3 - The presentation of results needs to be improved.

Response: We would appreciate a more specific indication of what should be improved. In the absence of those, we used the following notes of the reviewer as a guidance.

11) Reviewer 3 - Figures: Statistical analysis is missing. The letters relating to the significant differences are necessary to better understand the results and to make the paper publishable.

Response: We have identified significant differences with symbols ‘*’ and ‘#’ The symbol # - significant differences between lines, the symbol * - significant differences between bars).

2) Reviewer 3 - Lines 83-86: the concepts repeat themselves.

Response: we edited the sentences on the lines 83-86 to avoid the repetition.

Conclusions:

13) Reviewer 3 - It is necessary to rewrite this part because the results are presented again. Innovative solutions for apple producers to improve production should be included in this section.

Response: We have revised the conclusions according to the reviewer's suggestion

References:

14) Reviewer 3 - They must be completely overhauled to improve the formatting. Some are not clear, others should be updated.

Response: It is difficult to do so in the absence of specific directions of the reviewer, but we did our best to follow this advice.  

Minor comments:

15) Reviewer 3 - Keywords: they must be different from those of the title to give greater visibility to the manuscript;

Response: We edited the keywords according to the Reviewer’s suggestion.

16) Reviewer 3 - Line 40: delete sentence, it's obvious;

Response:  We deleted “The roots mainly occupy the permanently irrigated soil volume.” according to the Reviewer’s suggestion

17) Reviewer 3 - Line 79: Delete "As stated above" (it's a new paragraph);

Response:  We deleted “As stated above” according to the Reviewer’s suggestion.

18) Reviewer 3 - Table 1: "42.1bb" is an error. Please correct;

Response:  We corrected this error.

19) Reviewer 3 - Review the English language.

Response:  We did our best to improve the English quality.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

1) Line 40 citation is incorrect. It should be [9-11].

2) Line155 and Line 180 headings are numbered with wrong numbers.

3) Line 314 "summer draught" or "summer drought" ?

4) I think the line spacing between lines 115-142, 155-179, 334-336, 384-402 is not appropriate according to the template. Because the file that I am reviewed is PDF, I could not clearly decide whether these situations are wrong or not. The spaces before and after the line spacing are not arranged according to the template in my opinion.

Author Response

Authors would like to thank Reviewer for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript.

1) Reviewer 1:  Line 40 citation is incorrect. It should be [9-11].

Response: We changed the numbers according to the Reviewer remark.

2) ) Reviewer 1:  Line155 and Line 180 headings are numbered with wrong numbers.

Response: We corrected the heading numbers.

3) Reviewer 1: Line 314 "summer draught" or "summer drought" ?

Response: We corrected this typo “summer drought”.

4) Reviewer 1: I think the line spacing between lines 115-142, 155-179, 334-336, 384-402 is not appropriate according to the template. Because the file that I am reviewed is PDF, I could not clearly decide whether these situations are wrong or not. The spaces before and after the line spacing are not arranged according to the template in my opinion.

Response: We corrected the spacing.

Reviewer 2 Report

The author has revised the paper accordingly and I have nothing further to add.

Author Response

Authors would like to thank Reviewer for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript.

Reviewer 3 Report

Dear authors,

there are still some points that need to be improved before the paper can be considered for publication. It is recommended to include a chemical-physical characterization of the experimental soils, not the pedological one. 

Furthermore, the symbols relating to the statistical analysis inserted in the figures are not clear, letters should be inserted. 

Finally, the references section should be formatted following the journal's guidelines and articles in Russian are difficult to find, if possible, replace them with papar in English.

I kindly ask the authors to send a version with the track changes, otherwise identifying the revisions made is not easy.

Best regards

Author Response

Authors would like to thank Reviewer for taking the necessary time and effort to review the manuscript. We sincerely appreciate all your valuable comments and suggestions, which helped us in improving the quality of the manuscript.

Dear authors,

there are still some points that need to be improved before the paper can be considered for publication.

Reviewer 3 : It is recommended to include a chemical-physical characterization of the experimental soils, not the pedological one. 

Response: We added the data about the humus content, field capacity, and cation exchange capacity.

Reviewer 3 : Furthermore, the symbols relating to the statistical analysis inserted in the figures are not clear, letters should be inserted. 

Response: We replaced the symbols with letters.

Reviewer 3 : Finally, the references section should be formatted following the journal's guidelines and articles in Russian are difficult to find, if possible, replace them with papar in English.

Response: We did our best to format the reference section following the journal guidelines. We found new articles in English to replace them Russian sources according to the respected Reviewer suggestion, because it would be very hard to find the thesis of Mr. Suvorov where is the perfect study of root architectonics  of some apple cultivars grafted on B118 rootstock, so we add the Figure from this thesis.

Reviewer 3 : I kindly ask the authors to send a version with the track changes, otherwise identifying the revisions made is not easy.

Response: We are attaching the word version with the track changes.