Maize and Wheat Response to Drought Stress under Varied Sulphur Fertilisation

Round 1

Reviewer 1 Report

This is a very interesting study. The author systematically studied the influence of long-lasting water stress and application of sulphur on growth, yield, and mineral composition of wheat and maize. And they finally found out the sulphur fertilisation may be recommended in wheat cultivation when plants are exposed to moderate water stress. The Manuscript may be published in the Agronomy after major revision. My review comments as follows.

1. The research content of the manuscript cannot support the title of the manuscript. It should be closely related to the research content and need to be modified.
2. The introduction does not provide sufficient background and relevant references and must be improved.
3. The long-lasting water stress-controlled methods should be explained in details, which is important to evaluate if the experimental design was scientific?
4. Meteorological data during the test in the field should be supplemented.
5. Why wheat was collected at full maturity stage, while maize was collected at full bloom stage ( BBCH 67 ).
6. Results and Discussion (3.2.1. Macroelements), The order of macroelements analysis should be consistent with the order in the table.
7. The result and discussion was not sufficiently in-depth, and further in-depth discussion is required
8. Minor revision, especially English revision and format, is required.

Author Response

Dear Reviewer,

Thank you very much for your very constructive and valuable opinions and suggestions that will improve our manuscript. Thank for your times and engagement.

Preparing the current version of manuscript we took into account almost all suggestions and recommendations.

Below is presented general information about  a correction that  was done:

A chapter Introduction was modified. On line with recommendation of all Reviewers we have considerably expanded information about drought  and  drought and sulphur fertilization. We have presented an aim of our research against the background of literature data. We introduced relevant references including three new ones:

Seleiman, M.F.; Al-Suhaibani, N.; Ali, N.; Akmal, M.; Alotaibi, M.; Refay, Y.; Dindaroglu, T.; Abdul-Wajid, H.H.; Battaglia, M.L. 2021. Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects. Plants 2021, 10, 259.

Usmani MM, Nawaz F, Majeed S, Shehzad MA, Ahmad KS, Akhtar G, Aqib M, Shabbir RN. 2020. Sulfate-mediated Drought tolerance in Maize involves Regulation at physiological and
Biochemical Levels. Scientific Reports 10:1147 

Lee B-R, Zaman R, Avice J-C, Ourry A and Kim T-H. 2016 Sulfur Use Efficiency Is a Significant Determinant of Drought Stress Tolerance in Relation to Photosynthetic Activity in Brassica napus Cultivars. Front. Plant Sci. 7:459.doi: 10.3389/fpls.2016.00459

And four from previous list of references:

Ding L, Lu Z, Gao L, Guo S and Shen Q (2018) Is Nitrogen a Key Determinant of Water Transport and Photosynthesis in Higher Plants Upon Drought Stress? Front. Plant Sci. 9:1143. doi: 10.3389/fpls.2018.01143

Fahad S, Bajwa AA, Nazir U, Anjum SA, Farooq A, Zohaib A, Sadia S, Nasim W, Adkins S, Saud S, Ihsan MZ, Alharby H, Wu C, Wang D and Huang J.  2017. Crop Production under Drought and Heat Stress: Plant Responses and Management Options. Front. Plant Sci. 8:1147. doi: 10.3389/fpls.2017.01147

Chan KX, Wirtz M, Phua SY, Estavillo G.M., Pogson B.J. 2013. Balancing metabolites in drought: the sulfur assimilation conundrum. Trends in Plant Science 18(1): 18-29 doi.org/10.1016/j.tplants.2012.07.005

HuY.  Schmidhalter U. 2005. Drought and salinity: A comparison of their effects on mineral nutrition of plants. J. Plant Nutr. Soil Sci. 168, 541–549 

A chapter Materials and Methods was supplemented. We provided more details about a location of experiment and conditions under which plants were cultivated. A description of chemical and statistical analyses was also supplemented and relevant publications are added

Egner, H.; Riehm, H. Doppellaktatmethode. In Methodenbuch Band I. Die Untersuchung von Boden; Thun, R.;Hersemann, R.; Knickmann, E., Eds.; Neumann Verlag: Radebeul Berlin, 1955; pp. 110–125.

Schachtschabel, P. Das Pflanzenverfügbare Magnesium Des Boden Und Seine Bestimmung 1954. 67, 9–23.

Rinkis, G. Optimalisation of Mineral Nutrition of Plants; Zinatne: Riga, Latvija, 1972.

A chapter Results and Discussion was also improved. The chapter contains a lot of numerical data, hence is not easy for depiction and interpretation. We modified a description of obtained data and for each statement we added a source (figure or table). For higher clarity, we reformatted the description, inserted more paragraphs, introduced some slight change in an order of macroelements description and added two additional references:

Tränkner M., Tavakol E., Jákli B. 2018. Functioning of potassium and magnesium in photosynthesis, photosynthate translocation and photoprotection.  Physiologia Plantarum 163: 414–431

Li Y, , Sun CH , Huang Z , Pan J , Wang L, Fa X. 2009). Mechanisms of Progressive Water Deficit Tolerance and Growth Recovery of Chinese Maize Foundation Genotypes Huangzao 4 and Chang 7-2, Which are Proposed on the Basis of Comparison of Physiological and Transcriptomic Responses. Plant Cell Physiol. 50(12): 2092–2111 doi:10.1093/pcp/pcp145

Responses to the Reviewer's comments:

 The research content of the manuscript cannot support the title of the manuscript. It should be closely related to the research content and need to be

In our opinion, the title is short and concise and adequately reflects the research carried out

2. The introduction does not provide sufficient background and relevant references and must be

This has been corrected

3. The long-lasting water stress-controlled methods should be explained in details, which is important to evaluate if the experimental design was scientific?

Soil moisture was maintained throughout the entire vegetation period of the cultivated plants at 30%, 45%, and 60% field capacity. Additional information on the growing conditions of the plants has been completed.

4. Meteorological data during the test in the field should be supplemented.

Additional information on the growing conditions of the plants has been completed.

5. Why wheat was collected at full maturity stage, while maize was collected at full bloom stage ( BBCH 67 ).

In pot experiments, it is very difficult to bring maize to full maturity,

6. Results and Discussion (3.2.1. Macroelements), The order of macroelements analysis should be consistent with the order in the

This chapter has been rearanged

7. The result and discussion was not sufficiently in-depth, and further in-depth discussion is required

We have expanded this chapter and introduced supplementary literature

8. Minor revision, especially English revision and format, is required.

The manuscript has been proofread by a professional English language service (Cambridge Proofreading®)

Reviewer 2 Report

The authors compared the reactions of wheat and maize to long-lasting moderate and severe drought stress and examined the response to drought stress under sulphur fertilization. Although the concept looks interesting, the manuscript is poorly written. Some sections need to be improved.

1. Introduction

The introduction doesn't provide sufficient background and doesn't include all relevant references. The information provided is incomplete. The introduction requires significant supplementation and expansion. The authors cited only 5 references, including 2 own publications.

The latest references should be added.
It should be emphasized in more detail what is the novelty of the present study against the background of literature data.

2. Materials and Methods

Please describe the location of the experiments in detail.

line 45: Why are these names in italics? Please correct it.

The methods and statistical analysis are too briefly described.

Subsection 3.1. Plant growth and yield should be described and discussed in more detail.

The directions of further research should be indicated in the Conclusions.

Author Response

Dear Reviewer,

Thank you very much for your very constructive and valuable opinions and suggestions that will improve our manuscript. Thank for your times and engagement.

Preparing the current version of manuscript we took into account almost all suggestions and recommendations.

Below is presented general information about  a correction that  was done:

A chapter Introduction was modified. On line with recommendation of all Reviewers we have considerably expanded information about drought  and  drought and sulphur fertilization. We have presented an aim of our research against the background of literature data. We introduced relevant references including three new ones:

Seleiman, M.F.; Al-Suhaibani, N.; Ali, N.; Akmal, M.; Alotaibi, M.; Refay, Y.; Dindaroglu, T.; Abdul-Wajid, H.H.; Battaglia, M.L. 2021. Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects. Plants 2021, 10, 259.

Usmani MM, Nawaz F, Majeed S, Shehzad MA, Ahmad KS, Akhtar G, Aqib M, Shabbir RN. 2020. Sulfate-mediated Drought tolerance in Maize involves Regulation at physiological and
Biochemical Levels. Scientific Reports 10:1147 

Lee B-R, Zaman R, Avice J-C, Ourry A and Kim T-H. 2016 Sulfur Use Efficiency Is a Significant Determinant of Drought Stress Tolerance in Relation to Photosynthetic Activity in Brassica napus Cultivars. Front. Plant Sci. 7:459.doi: 10.3389/fpls.2016.00459

And four from previous list of references:

Ding L, Lu Z, Gao L, Guo S and Shen Q (2018) Is Nitrogen a Key Determinant of Water Transport and Photosynthesis in Higher Plants Upon Drought Stress? Front. Plant Sci. 9:1143. doi: 10.3389/fpls.2018.01143

Fahad S, Bajwa AA, Nazir U, Anjum SA, Farooq A, Zohaib A, Sadia S, Nasim W, Adkins S, Saud S, Ihsan MZ, Alharby H, Wu C, Wang D and Huang J.  2017. Crop Production under Drought and Heat Stress: Plant Responses and Management Options. Front. Plant Sci. 8:1147. doi: 10.3389/fpls.2017.01147

Chan KX, Wirtz M, Phua SY, Estavillo G.M., Pogson B.J. 2013. Balancing metabolites in drought: the sulfur assimilation conundrum. Trends in Plant Science 18(1): 18-29 doi.org/10.1016/j.tplants.2012.07.005

HuY.  Schmidhalter U. 2005. Drought and salinity: A comparison of their effects on mineral nutrition of plants. J. Plant Nutr. Soil Sci. 168, 541–549 

A chapter Materials and Methods was supplemented. We provided more details about a location of experiment and conditions under which plants were cultivated. A description of chemical and statistical analyses was also supplemented and relevant publications are added

Egner, H.; Riehm, H. Doppellaktatmethode. In Methodenbuch Band I. Die Untersuchung von Boden; Thun, R.;Hersemann, R.; Knickmann, E., Eds.; Neumann Verlag: Radebeul Berlin, 1955; pp. 110–125.

Schachtschabel, P. Das Pflanzenverfügbare Magnesium Des Boden Und Seine Bestimmung 1954. 67, 9–23.

Rinkis, G. Optimalisation of Mineral Nutrition of Plants; Zinatne: Riga, Latvija, 1972.

A chapter Results and Discussion was also improved. The chapter contains a lot of numerical data, hence is not easy for depiction and interpretation. We modified a description of obtained data and for each statement we added a source (figure or table). For higher clarity, we reformatted the description, inserted more paragraphs, introduced some slight change in an order of macroelements description and added two additional references:

Tränkner M., Tavakol E., Jákli B. 2018. Functioning of potassium and magnesium in photosynthesis, photosynthate translocation and photoprotection.  Physiologia Plantarum 163: 414–431

Li Y, , Sun CH , Huang Z , Pan J , Wang L, Fa X. 2009). Mechanisms of Progressive Water Deficit Tolerance and Growth Recovery of Chinese Maize Foundation Genotypes Huangzao 4 and Chang 7-2, Which are Proposed on the Basis of Comparison of Physiological and Transcriptomic Responses. Plant Cell Physiol. 50(12): 2092–2111 doi:10.1093/pcp/pcp145

Responses to the Reviewer's comments:

1. Introduction

The introduction doesn't provide sufficient background and doesn't include all relevant references. The information provided is incomplete. The introduction requires significant supplementation and expansion. The authors cited only 5 references, including 2 own publications.

The latest references should be added.

It should be emphasized in more detail what is the novelty of the present study against the background of literature data.

As mentioned above, the introduction has been significantly expanded and relevant literature items have been added

2. Materials and Methods

Please describe the location of the experiments in detail.

Additional information has been completed.

line 45: Why are these names in italics? Please correct it.

This has been corrected

The methods and statistical analysis are too briefly described.

Additional information has been completed.

Subsection 3.1. Plant growth and yield should be described and discussed in more detail.

We have expanded this chapter and introduced supplementary literature

The directions of further research should be indicated in the Conclusions.

Conclusions were supplemented with this suggestion

Reviewer 3 Report

Dear authors,

Thank you for the opportunity to meet the manuscript entitled: "Maize and wheat response to drought stress under varied sulphur fertilization". Drought stress is currently probably the most limiting factor in field crop production. It is therefore necessary to find an effective way to mitigate the negative effect of this factor. Therefore, I evaluate the choice of topic positively, although I have some fundamental comments and remarks on the creation of this manuscript:

To study the effect of drought on plant growth and development, it is currently necessary to monitor not only the basic production parameters, but also the change in the physiological status of plants. From this point of view, I consider this research to be insufficient.

The authors did not sufficiently process the chapter Introduction. It lacks basic information on the topic and also uses few literary sources. This section must be modified.

It is a great challenge to compare two different types (C3 and C4) of plants. It is necessary to approach the evaluation very sensitively. The authors have often failed to do this. Eg: L83-89 In my opinion, it is inappropriate to compare the size of the reduction in both monitored crops. Wheat was also harvested at the full maturity stage, while corn was not. This can have a significant effect on the results.

It is often not clear from the evaluated results whether the authors evaluated the influence of factors on the traits individually or in interactions. Therefore, I recommend for each statement to indicate the source (figure) where the results are presented. It is not enough to mark Figure 1, 2, 3 at the end of the sentence. It is also important to always mention which plant the authors are writing about. The Results chapter is very confusing.

Some results are misinterpreted in the Abstract and Results, respectively:

L6 "Moderate drought stress did not significantly change the wheat grain yield" Based on the results of Figure 1b, I do not agree.

L6-7 "... applying sulphur considerably improved wheat productivity." Not true. Wheat production was reduced by the application of S fertilizer (Figures 1c and 2c)

L78-79 Incorrect conclusion. Based on Figure 2, it can be concluded that wheat reacted negatively to sulphur fertilization, while a slight increase in fresh mass was found when fertilizing maize with elemental sulphur. It is also not clear why the authors evaluated that wheat is more tolerant to water stress. In both cases, the results were equally statistically significant.

In general, the results presented in this manuscript did not provide any new information. It has only been confirmed that the effect of drought stress is more significant than sulphur fertilization. However, as I mentioned above, it would be beneficial to find out what effect sulphur fertilization in combination with drought stress has on the physiological status of plants. Unfortunately, this has not been the subject of research.

Author Response

Dear Reviewer,

Thank you very much for your very constructive and valuable opinions and suggestions that will improve our manuscript. Thank for your times and engagement.

Preparing the current version of manuscript we took into account almost all suggestions and recommendations.

Below is presented general information about  a correction that  was done:

A chapter Introduction was modified. On line with recommendation of all Reviewers we have considerably expanded information about drought  and  drought and sulphur fertilization. We have presented an aim of our research against the background of literature data. We introduced relevant references including three new ones:

Seleiman, M.F.; Al-Suhaibani, N.; Ali, N.; Akmal, M.; Alotaibi, M.; Refay, Y.; Dindaroglu, T.; Abdul-Wajid, H.H.; Battaglia, M.L. 2021. Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects. Plants 2021, 10, 259.

Usmani MM, Nawaz F, Majeed S, Shehzad MA, Ahmad KS, Akhtar G, Aqib M, Shabbir RN. 2020. Sulfate-mediated Drought tolerance in Maize involves Regulation at physiological and
Biochemical Levels. Scientific Reports 10:1147 

Lee B-R, Zaman R, Avice J-C, Ourry A and Kim T-H. 2016 Sulfur Use Efficiency Is a Significant Determinant of Drought Stress Tolerance in Relation to Photosynthetic Activity in Brassica napus Cultivars. Front. Plant Sci. 7:459.doi: 10.3389/fpls.2016.00459

And four from previous list of references:

Ding L, Lu Z, Gao L, Guo S and Shen Q (2018) Is Nitrogen a Key Determinant of Water Transport and Photosynthesis in Higher Plants Upon Drought Stress? Front. Plant Sci. 9:1143. doi: 10.3389/fpls.2018.01143

Fahad S, Bajwa AA, Nazir U, Anjum SA, Farooq A, Zohaib A, Sadia S, Nasim W, Adkins S, Saud S, Ihsan MZ, Alharby H, Wu C, Wang D and Huang J.  2017. Crop Production under Drought and Heat Stress: Plant Responses and Management Options. Front. Plant Sci. 8:1147. doi: 10.3389/fpls.2017.01147

Chan KX, Wirtz M, Phua SY, Estavillo G.M., Pogson B.J. 2013. Balancing metabolites in drought: the sulfur assimilation conundrum. Trends in Plant Science 18(1): 18-29 doi.org/10.1016/j.tplants.2012.07.005

HuY.  Schmidhalter U. 2005. Drought and salinity: A comparison of their effects on mineral nutrition of plants. J. Plant Nutr. Soil Sci. 168, 541–549 

A chapter Materials and Methods was supplemented. We provided more details about a location of experiment and conditions under which plants were cultivated. A description of chemical and statistical analyses was also supplemented and relevant publications are added

Egner, H.; Riehm, H. Doppellaktatmethode. In Methodenbuch Band I. Die Untersuchung von Boden; Thun, R.;Hersemann, R.; Knickmann, E., Eds.; Neumann Verlag: Radebeul Berlin, 1955; pp. 110–125.

Schachtschabel, P. Das Pflanzenverfügbare Magnesium Des Boden Und Seine Bestimmung 1954. 67, 9–23.

Rinkis, G. Optimalisation of Mineral Nutrition of Plants; Zinatne: Riga, Latvija, 1972.

A chapter Results and Discussion was also improved. The chapter contains a lot of numerical data, hence is not easy for depiction and interpretation. We modified a description of obtained data and for each statement we added a source (figure or table). For higher clarity, we reformatted the description, inserted more paragraphs, introduced some slight change in an order of macroelements description and added two additional references:

Tränkner M., Tavakol E., Jákli B. 2018. Functioning of potassium and magnesium in photosynthesis, photosynthate translocation and photoprotection.  Physiologia Plantarum 163: 414–431

Li Y, , Sun CH , Huang Z , Pan J , Wang L, Fa X. 2009). Mechanisms of Progressive Water Deficit Tolerance and Growth Recovery of Chinese Maize Foundation Genotypes Huangzao 4 and Chang 7-2, Which are Proposed on the Basis of Comparison of Physiological and Transcriptomic Responses. Plant Cell Physiol. 50(12): 2092–2111 doi:10.1093/pcp/pcp145

Responses to the Reviewer's comments:

To study the effect of drought on plant growth and development, it is currently necessary to monitor not only the basic production parameters, but also the change in the physiological status of plants. From this point of view, I consider this research to be insufficient.

We are aware that the research could be more wide ranging, including the assessment of physiological parameter. However, interactions of mineral elements in plant nutrition are very important and have a significant impact on the physiological status of plants. In our opinion, topics related to mineral element interactions are underestimated and relatively unrecognised.

The authors did not sufficiently process the chapter Introduction. It lacks basic information on the topic and also uses few literary sources. This section must be modified.

As mentioned above, the introduction has been significantly expanded and relevant literature items have been added

It is a great challenge to compare two different types (C3 and C4) of plants. It is necessary to approach the evaluation very sensitively. The authors have often failed to do this. Eg: L83-89 In my opinion, it is inappropriate to compare the size of the reduction in both monitored crops. Wheat was also harvested at the full maturity stage, while corn was not. This can have a significant effect on the results.

We followed this suggestion

It is often not clear from the evaluated results whether the authors evaluated the influence of factors on the traits individually or in interactions. Therefore, I recommend for each statement to indicate the source (figure) where the results are presented. It is not enough to mark Figure 1, 2, 3 at the end of the sentence. It is also important to always mention which plant the authors are writing about. The Results chapter is very confusing.

As mentioned above,  for higher clarity, we reformatted the description, inserted more paragraphs, introduced some slight change in an order of macroelements description and added two additional references. We modified a description of obtained data and for each statement we added a source (figure or table).

Some results are misinterpreted in the Abstract and Results, respectively:

We have changed these parts of the text

L6 "Moderate drought stress did not significantly change the wheat grain yield" Based on the results of Figure 1b, I do not agree.

To better clarity (Fig. 1a): 

“Under both optimal water conditions (60% FWC) and moderate water stress (45% FWC) grain yields of wheat grown without sulphur application were not significantly different. Applying elemental sulphur caused an increase in grain yield under moderate stress whereas sulphate was more effective in wheat grown under adequate water supply.”

L6-7 "... applying sulphur considerably improved wheat productivity." Not true. Wheat production was reduced by the application of S fertilizer (Figures 1c and 2c)

Thank you for noticing because the figures (1c, 2c) were formatted incorrectly, and we have corrected them

L78-79 Incorrect conclusion. Based on Figure 2, it can be concluded that wheat reacted negatively to sulphur fertilization, while a slight increase in fresh mass was found when fertilizing maize with elemental sulphur. It is also not clear why the authors evaluated that wheat is more tolerant to water stress. In both cases, the results were equally statistically significant.

As suggested, we have removed direct comparisons between wheat and maize and this sentence has been deleted.

In general, the results presented in this manuscript did not provide any new information. It has only been confirmed that the effect of drought stress is more significant than sulphur fertilization. However, as I mentioned above, it would be beneficial to find out what effect sulphur fertilization in combination with drought stress has on the physiological status of plants. Unfortunately, this has not been the subject of research.

What is new in our study is the determination of the interaction of drought and sulphur fertilisation with their different forms, especially the elemental form of sulphur.

Reviewer 4 Report

The problem of drought has been a growing problem in agricultural production in recent years. Therefore, in my opinion, the research on the impact of drought on plants and the possibility of alleviating the effects of this stress, e.g. through sulfur fertilization, is up-to-date and interesting. Manuscript is basically well written, the results are presented and discussed clearly. I have some comments that may improve the quality of the manuscript:

 

1. The introduction is too general. More information should be provided on the effect of drought and sulfur fertilization on the yield and composition of plants. Including various forms of sulfur. There is no information at all as to whether such studies have already been conducted, or whether there are any dependencies. What has already been explained and what still requires further research.

 

2. Table 1. - the content of available forms should be given in mg kg^-1. It should be stated which methods were used to determine the soil properties given in the table.
3. Line [40-41] - On the basis of which standards (limit numbers) the level of soil abundance in macro and microelements was determined.
4. Table 2 - it is worth specifying which dose per hectare corresponded to the sulfur doses used in the research
5. Please provide more details about the conditions under which the experiment was conducted. They were conducted in a vegetation hall, in a greenhouse? Were the parameters, i.e. temperature, lighting adjustable?
6. How many wheat or maize plants were planted in each vase
7. Line [120 and other] - it is more appropriate to use the term 'in maize biomass' instead of 'in maize shoots'
8. Table 6 and 7 - it is probably in mg kg^-1 and not in g kg^-1?
9. Table 8 - twice there is S-SO₄ as a form of sulfur

Author Response

Dear Reviewer,

Thank you very much for your very constructive and valuable opinions and suggestions that will improve our manuscript. Thank for your times and engagement.

Preparing the current version of manuscript we took into account almost all suggestions and recommendations.

Below is presented general information about  a correction that  was done:

A chapter Introduction was modified. On line with recommendation of all Reviewers we have considerably expanded information about drought  and  drought and sulphur fertilization. We have presented an aim of our research against the background of literature data. We introduced relevant references including three new ones:

Seleiman, M.F.; Al-Suhaibani, N.; Ali, N.; Akmal, M.; Alotaibi, M.; Refay, Y.; Dindaroglu, T.; Abdul-Wajid, H.H.; Battaglia, M.L. 2021. Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects. Plants 2021, 10, 259.

Usmani MM, Nawaz F, Majeed S, Shehzad MA, Ahmad KS, Akhtar G, Aqib M, Shabbir RN. 2020. Sulfate-mediated Drought tolerance in Maize involves Regulation at physiological and
Biochemical Levels. Scientific Reports 10:1147 

Lee B-R, Zaman R, Avice J-C, Ourry A and Kim T-H. 2016 Sulfur Use Efficiency Is a Significant Determinant of Drought Stress Tolerance in Relation to Photosynthetic Activity in Brassica napus Cultivars. Front. Plant Sci. 7:459.doi: 10.3389/fpls.2016.00459

And four from previous list of references:

Ding L, Lu Z, Gao L, Guo S and Shen Q (2018) Is Nitrogen a Key Determinant of Water Transport and Photosynthesis in Higher Plants Upon Drought Stress? Front. Plant Sci. 9:1143. doi: 10.3389/fpls.2018.01143

Fahad S, Bajwa AA, Nazir U, Anjum SA, Farooq A, Zohaib A, Sadia S, Nasim W, Adkins S, Saud S, Ihsan MZ, Alharby H, Wu C, Wang D and Huang J.  2017. Crop Production under Drought and Heat Stress: Plant Responses and Management Options. Front. Plant Sci. 8:1147. doi: 10.3389/fpls.2017.01147

Chan KX, Wirtz M, Phua SY, Estavillo G.M., Pogson B.J. 2013. Balancing metabolites in drought: the sulfur assimilation conundrum. Trends in Plant Science 18(1): 18-29 doi.org/10.1016/j.tplants.2012.07.005

HuY.  Schmidhalter U. 2005. Drought and salinity: A comparison of their effects on mineral nutrition of plants. J. Plant Nutr. Soil Sci. 168, 541–549 

A chapter Materials and Methods was supplemented. We provided more details about a location of experiment and conditions under which plants were cultivated. A description of chemical and statistical analyses was also supplemented and relevant publications are added

Egner, H.; Riehm, H. Doppellaktatmethode. In Methodenbuch Band I. Die Untersuchung von Boden; Thun, R.;Hersemann, R.; Knickmann, E., Eds.; Neumann Verlag: Radebeul Berlin, 1955; pp. 110–125.

Schachtschabel, P. Das Pflanzenverfügbare Magnesium Des Boden Und Seine Bestimmung 1954. 67, 9–23.

Rinkis, G. Optimalisation of Mineral Nutrition of Plants; Zinatne: Riga, Latvija, 1972.

A chapter Results and Discussion was also improved. The chapter contains a lot of numerical data, hence is not easy for depiction and interpretation. We modified a description of obtained data and for each statement we added a source (figure or table). For higher clarity, we reformatted the description, inserted more paragraphs, introduced some slight change in an order of macroelements description and added two additional references:

Tränkner M., Tavakol E., Jákli B. 2018. Functioning of potassium and magnesium in photosynthesis, photosynthate translocation and photoprotection.  Physiologia Plantarum 163: 414–431

Li Y, , Sun CH , Huang Z , Pan J , Wang L, Fa X. 2009). Mechanisms of Progressive Water Deficit Tolerance and Growth Recovery of Chinese Maize Foundation Genotypes Huangzao 4 and Chang 7-2, Which are Proposed on the Basis of Comparison of Physiological and Transcriptomic Responses. Plant Cell Physiol. 50(12): 2092–2111 doi:10.1093/pcp/pcp145

Responses to the Reviewer's comments:

1. The introduction is too general. More information should be provided on the effect of drought and sulfur fertilization on the yield and composition of plants. Including various forms of sulfur. There is no information at all as to whether such studies have already been conducted, or whether there are any dependencies. What has already been explained and what still requires further research.

As mentioned above, the introduction has been significantly expanded and relevant literature items have been added

2. Table 1. - the content of available forms should be given in mg kg-1. It should be stated which methods were used to determine the soil properties given in the table.

The unit in the table has been corrected, methods have been added

3. Line [40-41] - On the basis of which standards (limit numbers) the level of soil abundance in macro and microelements was determined.

Soil abundance limits values were determined based on the soil test methods used, literature references for the methods used have been added in the test methods chapter

4. Table 2 - it is worth specifying which dose per hectare corresponded to the sulfur doses used in the research

Direct conversion of fertiliser doses applied in pot experiments to field conditions is due to their different specificity and such conversions are not practical

5. Please provide more details about the conditions under which the experiment was conducted. They were conducted in a vegetation hall, in a greenhouse? Were the parameters, i.e. temperature, lighting adjustable?

Additional information has been completed.

6. How many wheat or maize plants were planted in each vase

Additional information has been completed.

7. Line [120 and other] - it is more appropriate to use the term 'in maize biomass' instead of 'in maize shoots'

In our opinion, the term shoots is more precise than the term biomass, which may suggest the whole plant (above-ground parts with roots)

8. Table 6 and 7 - it is probably in mg kg-1 and not in g kg-1?

The unit in the table has been corrected

9. Table 8 - twice there is S-SO4 as a form of sulfur

Thank you for pointing out, the tables have been corrected

Round 2

Reviewer 2 Report

All my comments have been considered and included. The manuscript has been sufficiently improved.

Reviewer 3 Report

Dear authors, I appreciate you taking my comments into account and adjusting the manuscript accordingly.

I believe this has helped to increase its quality.