Physiological and Chemical Response of Urochloa brizantha to Edaphic and Microclimatic Variations Along an Altitudinal Gradient in the Amazon

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors present a methodology that enables the results obtained.
Regarding the results, the soil class of each collection site along the topographic gradient studied should be specified.
The authors could better explain the lack of difference in forage productivity and the variation in fertility between collection sites. Even though there was virtually no difference in forage production, a difference in its chemical composition was observed. Why did this occur? This should be detailed.
The assertion that the Fabaceae family improves forage cannot, in my opinion, be confirmed by this study. For this, forage should have been collected from trees of only a few families and compared.
Better use should be made of the results observed regarding the number and size of stomata and why this had no influence on the results obtained.

Author Response

Responses to Reviewer 1
Comment 1. Regarding the results, the soil class of each collection site along the topographic gradient studied should be specified. The authors could better explain the lack of difference in forage productivity and the variation in fertility between collection sites. Even though there was virtually no difference in forage production, a difference in its chemical composition was observed. Why did this occur? This should be detailed. The assertion that the Fabaceae family improves forage cannot, in my opinion, be confirmed by this study. For this, forage should have been collected from trees of only a few families and compared. Better use should be made of the results observed regarding the number and size of stomata and why this had no influence on the results obtained.
Response: The reviewer's recommendations were followed, the soil was classified according to its texture, and better use was made of the results, highlighted in the conclusions.
Responses to Reviewer 2
Comment 1. The manuscript addresses a relevant aspect of silvopasture systems applicable to management of similar tropical forage grasses. While the focus of the manuscript, as in title and study objective, is on physiological and chemical responses of Brachiaria Brizantha to environmental variations, the results and conclusions also address tree responses. May need to be modified to address both or be clarified.
Response: We have made the suggested change.
Line 77 – change with “this forage grass”
Comment 2. Table 4 “Which fiber category? are NDF and ADF not subcategories of fiber? If so how come their proportions are way larger than fiber?
Response: The reported NDF is between 60 to 75% which includes cellulose, hemicellulose and lignin, so it is higher. For SDF it is between 35 to 45%, because it excludes hemicellulose, so it is lower than NDF. Finally, Fiber is between 20 to 30% because it underestimates the total fiber, so its value is lower. Fiber is not currently reported in academic knowledge, but it is widely used by field technicians, so the authors consider that it should be kept in the article.
Responses to Reviewer 3
Line [199] - please give the temperature differences in degrees Celsius, not in %
Response: The reviewer's suggestion was complied with.
Line [201] – why such a low result for an altitude of 503 m above sea level for solar radiation decrease? Did the authors try to explain this in the Discussion? Fewer trees, smaller trees?
Response: The reviewer's suggestion was complied with.
Line [208] – in subsection 2.3 no information is given that pH, electrical conductivity, CaCO3 content, potassium content were determined. Please complete this. Specify by what methods.
Response: Added the methodology information for pH and EC observed by the reviewer.
Table 3 – what is MSD? In Tukey's test, HSD is counted. Are the results for altitude 503 and 661 for fresh matter and dry matter really well reported?. It is also strange that with such large differences in the obtained values, there was no statistical significance.
Response: MSD- Minimun Significant Difference, in Tukey's test
Please specify for which samples the results are given in Tables 3 and 4. For Brizantha in monoculture or for silvopastoral areas.
Response: They are indicated in parentheses in the first column of each table.
Table 4 – it is more correct to give the content of ingredients in g kg-1 rather than in %
Response: The authors want to keep the % since this information will also have a technical use for producers in the Peruvian Amazon. Since in the academy it can be easily transformed to g/kg by professionals with more specific knowledge.
Line [325] – Fig 4 not Fig.3, in linie [335] – Fig. 4F
Response: The order of the figures has been corrected
Please revise the Conclusion. In its current form, this is a shortened repetition of the results. Here there should be more generalized conclusions. Do the results have any practical significance? What other investigation should be performed?.
Response: The conclusions were improved
References need improvement, not provided as required by Agronomy
Response: The references were in accordance with the scientific journal's standards.
Responses to Reviewer 4
In Chapter 2.1. - Location of the study area: in order to have a much clearer presentation of the climatic conditions of the area, I believe that information on the multiannual average monthly temperatures and the dynamics of multiannual monthly precipitation would be useful, to compare with the conditions in the year of the study, as well as information on the soil types in the four locations where the experiment was located.
Response: These are areas that do not present climatic or edaphic information, because previously no academic studies were carried out.
In chapter 2.4. - Sample collection and biomass, details regarding the determination of leaf area and bibliographical specifications regarding the minimum number of plants required to determine morphological parameters such as plant height, stem diameter and others should be presented.
Response: Further details were added, as suggested.
The table and figures presented in the manuscript are correctly elaborated and well-placed in the text, but in chapter 3.7. - Stomatal Morphometry, an error has recorded in when citing the figure, figure 4 with its components should be cited and not figure 3.
Response: The order of the figures has been corrected
The conclusions drawn by the authors are consistent with the results obtained, but I believe that the effect of the altitudinal gradient should be better highlighted for a better agreement with the style of the manuscript.
Response: The conclusions were improved

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses a relevant aspect of silvopasture systems applicable to management of similar tropical forage grasses. While the focus of the manuscript, as in title and study objective, is on physiological and chemical responses of Brachiaria Brizantha to environmental variations, the results and conclusions also address tree responses. May need to be modified to address both or be clarified.

Comments for author File: Comments.pdf

Author Response

Responses to Reviewer 1
Comment 1. Regarding the results, the soil class of each collection site along the topographic gradient studied should be specified. The authors could better explain the lack of difference in forage productivity and the variation in fertility between collection sites. Even though there was virtually no difference in forage production, a difference in its chemical composition was observed. Why did this occur? This should be detailed. The assertion that the Fabaceae family improves forage cannot, in my opinion, be confirmed by this study. For this, forage should have been collected from trees of only a few families and compared. Better use should be made of the results observed regarding the number and size of stomata and why this had no influence on the results obtained.
Response: The reviewer's recommendations were followed, the soil was classified according to its texture, and better use was made of the results, highlighted in the conclusions.
Responses to Reviewer 2
Comment 1. The manuscript addresses a relevant aspect of silvopasture systems applicable to management of similar tropical forage grasses. While the focus of the manuscript, as in title and study objective, is on physiological and chemical responses of Brachiaria Brizantha to environmental variations, the results and conclusions also address tree responses. May need to be modified to address both or be clarified.
Response: We have made the suggested change.
Line 77 – change with “this forage grass”
Comment 2. Table 4 “Which fiber category? are NDF and ADF not subcategories of fiber? If so how come their proportions are way larger than fiber?
Response: The reported NDF is between 60 to 75% which includes cellulose, hemicellulose and lignin, so it is higher. For SDF it is between 35 to 45%, because it excludes hemicellulose, so it is lower than NDF. Finally, Fiber is between 20 to 30% because it underestimates the total fiber, so its value is lower. Fiber is not currently reported in academic knowledge, but it is widely used by field technicians, so the authors consider that it should be kept in the article.
Responses to Reviewer 3
Line [199] - please give the temperature differences in degrees Celsius, not in %
Response: The reviewer's suggestion was complied with.
Line [201] – why such a low result for an altitude of 503 m above sea level for solar radiation decrease? Did the authors try to explain this in the Discussion? Fewer trees, smaller trees?
Response: The reviewer's suggestion was complied with.
Line [208] – in subsection 2.3 no information is given that pH, electrical conductivity, CaCO3 content, potassium content were determined. Please complete this. Specify by what methods.
Response: Added the methodology information for pH and EC observed by the reviewer.
Table 3 – what is MSD? In Tukey's test, HSD is counted. Are the results for altitude 503 and 661 for fresh matter and dry matter really well reported?. It is also strange that with such large differences in the obtained values, there was no statistical significance.
Response: MSD- Minimun Significant Difference, in Tukey's test
Please specify for which samples the results are given in Tables 3 and 4. For Brizantha in monoculture or for silvopastoral areas.
Response: They are indicated in parentheses in the first column of each table.
Table 4 – it is more correct to give the content of ingredients in g kg-1 rather than in %
Response: The authors want to keep the % since this information will also have a technical use for producers in the Peruvian Amazon. Since in the academy it can be easily transformed to g/kg by professionals with more specific knowledge.
Line [325] – Fig 4 not Fig.3, in linie [335] – Fig. 4F
Response: The order of the figures has been corrected
Please revise the Conclusion. In its current form, this is a shortened repetition of the results. Here there should be more generalized conclusions. Do the results have any practical significance? What other investigation should be performed?.
Response: The conclusions were improved
References need improvement, not provided as required by Agronomy
Response: The references were in accordance with the scientific journal's standards.
Responses to Reviewer 4
In Chapter 2.1. - Location of the study area: in order to have a much clearer presentation of the climatic conditions of the area, I believe that information on the multiannual average monthly temperatures and the dynamics of multiannual monthly precipitation would be useful, to compare with the conditions in the year of the study, as well as information on the soil types in the four locations where the experiment was located.
Response: These are areas that do not present climatic or edaphic information, because previously no academic studies were carried out.
In chapter 2.4. - Sample collection and biomass, details regarding the determination of leaf area and bibliographical specifications regarding the minimum number of plants required to determine morphological parameters such as plant height, stem diameter and others should be presented.
Response: Further details were added, as suggested.
The table and figures presented in the manuscript are correctly elaborated and well-placed in the text, but in chapter 3.7. - Stomatal Morphometry, an error has recorded in when citing the figure, figure 4 with its components should be cited and not figure 3.
Response: The order of the figures has been corrected
The conclusions drawn by the authors are consistent with the results obtained, but I believe that the effect of the altitudinal gradient should be better highlighted for a better agreement with the style of the manuscript.
Response: The conclusions were improved

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In my opinion, the research presented in the manuscript is interesting and consistent with the profile of the journal ‘Agronomy”. The experiments presented in the manuscript were well planned and performed, it allows to explain the hypotheses put forward in the introduction. The results were statistically analyzed and discussed and interpreted in detail. Tables and graphs are generally well prepared, understandable and legible. However, the manuscript requires significant changes and additions.

 

General comments:

The weakness of the presented research is its short duration, including, as I understand, only one growing season. Therefore, it does not take into account, for example, the impact of weather conditions on the results obtained.

 

Specific comments:

If possible, please supplement the information with tree species occurring in individual research fields. There were probably not very many of them, because in the line [109] it is stated that 'Each area had a minimum of 5 trees per hectare...'

Could the occurrence of different tree species have had an impact on the results obtained?

Line [199] - please give the temperature differences in degrees Celsius, not in %

Line [201] – why such a low result for an altitude of 503 m above sea level for solar radiation decrease? Did the authors try to explain this in the Discussion? Fewer trees, smaller trees?

Line [208] – in subsection 2.3 no information is given that pH, electrical conductivity, CaCO3 content, potassium content were determined. Please complete this. Specify by what methods.

Table 3 – what is MSD? In Tukey's test, HSD is counted. Are the results for altitude 503 and 661 for fresh matter and dry matter really well reported?. It is also strange that with such large differences in the obtained values, there was no statistical significance.

In my opinion, it is not appropriate to apply biomass per hectare when samples were taken from a small area. It is better to serve on 1 m2.

Please specify for which samples the results are given in Tables 3 and 4. For Brizantha in monoculture or for silvopastoral areas.

Table 4 – it is more correct to give the content of ingredients in g kg-1 rather than in %

Line [325] – Fig 4 not Fig.3, in linie [335] – Fig. 4F

Please revise the Conclusion. In its current form, this is a shortened repetition of the results. Here there should be more generalized conclusions. Do the results have any practical significance? What other investigation should be performed?.

References need improvement, not provided as required by Agronomy

Author Response

Responses to Reviewer 1
Comment 1. Regarding the results, the soil class of each collection site along the topographic gradient studied should be specified. The authors could better explain the lack of difference in forage productivity and the variation in fertility between collection sites. Even though there was virtually no difference in forage production, a difference in its chemical composition was observed. Why did this occur? This should be detailed. The assertion that the Fabaceae family improves forage cannot, in my opinion, be confirmed by this study. For this, forage should have been collected from trees of only a few families and compared. Better use should be made of the results observed regarding the number and size of stomata and why this had no influence on the results obtained.
Response: The reviewer's recommendations were followed, the soil was classified according to its texture, and better use was made of the results, highlighted in the conclusions.
Responses to Reviewer 2
Comment 1. The manuscript addresses a relevant aspect of silvopasture systems applicable to management of similar tropical forage grasses. While the focus of the manuscript, as in title and study objective, is on physiological and chemical responses of Brachiaria Brizantha to environmental variations, the results and conclusions also address tree responses. May need to be modified to address both or be clarified.
Response: We have made the suggested change.
Line 77 – change with “this forage grass”
Comment 2. Table 4 “Which fiber category? are NDF and ADF not subcategories of fiber? If so how come their proportions are way larger than fiber?
Response: The reported NDF is between 60 to 75% which includes cellulose, hemicellulose and lignin, so it is higher. For SDF it is between 35 to 45%, because it excludes hemicellulose, so it is lower than NDF. Finally, Fiber is between 20 to 30% because it underestimates the total fiber, so its value is lower. Fiber is not currently reported in academic knowledge, but it is widely used by field technicians, so the authors consider that it should be kept in the article.
Responses to Reviewer 3
Line [199] - please give the temperature differences in degrees Celsius, not in %
Response: The reviewer's suggestion was complied with.
Line [201] – why such a low result for an altitude of 503 m above sea level for solar radiation decrease? Did the authors try to explain this in the Discussion? Fewer trees, smaller trees?
Response: The reviewer's suggestion was complied with.
Line [208] – in subsection 2.3 no information is given that pH, electrical conductivity, CaCO3 content, potassium content were determined. Please complete this. Specify by what methods.
Response: Added the methodology information for pH and EC observed by the reviewer.
Table 3 – what is MSD? In Tukey's test, HSD is counted. Are the results for altitude 503 and 661 for fresh matter and dry matter really well reported?. It is also strange that with such large differences in the obtained values, there was no statistical significance.
Response: MSD- Minimun Significant Difference, in Tukey's test
Please specify for which samples the results are given in Tables 3 and 4. For Brizantha in monoculture or for silvopastoral areas.
Response: They are indicated in parentheses in the first column of each table.
Table 4 – it is more correct to give the content of ingredients in g kg-1 rather than in %
Response: The authors want to keep the % since this information will also have a technical use for producers in the Peruvian Amazon. Since in the academy it can be easily transformed to g/kg by professionals with more specific knowledge.
Line [325] – Fig 4 not Fig.3, in linie [335] – Fig. 4F
Response: The order of the figures has been corrected
Please revise the Conclusion. In its current form, this is a shortened repetition of the results. Here there should be more generalized conclusions. Do the results have any practical significance? What other investigation should be performed?.
Response: The conclusions were improved
References need improvement, not provided as required by Agronomy
Response: The references were in accordance with the scientific journal's standards.
Responses to Reviewer 4
In Chapter 2.1. - Location of the study area: in order to have a much clearer presentation of the climatic conditions of the area, I believe that information on the multiannual average monthly temperatures and the dynamics of multiannual monthly precipitation would be useful, to compare with the conditions in the year of the study, as well as information on the soil types in the four locations where the experiment was located.
Response: These are areas that do not present climatic or edaphic information, because previously no academic studies were carried out.
In chapter 2.4. - Sample collection and biomass, details regarding the determination of leaf area and bibliographical specifications regarding the minimum number of plants required to determine morphological parameters such as plant height, stem diameter and others should be presented.
Response: Further details were added, as suggested.
The table and figures presented in the manuscript are correctly elaborated and well-placed in the text, but in chapter 3.7. - Stomatal Morphometry, an error has recorded in when citing the figure, figure 4 with its components should be cited and not figure 3.
Response: The order of the figures has been corrected
The conclusions drawn by the authors are consistent with the results obtained, but I believe that the effect of the altitudinal gradient should be better highlighted for a better agreement with the style of the manuscript.
Response: The conclusions were improved

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

In this peer-reviewed manuscript, the authors present the results of a single-year in situ study on the physiological and chemical response of Brachiaria brizantha to cultivation under different edaphic and microclimatic conditions, over an altitudinal gradient from 170 m to 1110 m. The effect of the cultivation method, on the one hand in open, sunny fields and on the other hand in partially shaded, silvopastoral areas and the time of harvest, with five graduations, 15, 30, 45, 60 and 75 days from the uniforming cut after the plants emerge, at four altitudes, 170, 503, 661 and 1110 m, on some physiological and quality characteristics of the fodder obtained from Brachiaria brizantha, a species very well adapted to tropical areas, with a very important economic and ecological role, was monitored, so that any study that can bring concrete elements regarding the behavior of this species under different conditions is of great help to farmers. The results obtained can contribute to increasing the scientific fund regarding the cultivation and harvesting of the Brachiaria brizantha species.

I believe that the topic addressed is of broad interest for the tropical areas of Peru, but also in other regions, where the Brachiaria brizantha species is very well adapted and even if it is not an absolute novelty, it will certainly bring important practical contributions for farmers.

The research methodology is correct, appropriate to the parameters studied, the presentation of the results and the statistical interpretation are those usually used in determinations of this type.

In order to have a clearer presentation of the experimental conditions, I believe that some additional information would be necessary:

In Chapter 2.1. - Location of the study area: in order to have a much clearer presentation of the climatic conditions of the area, I believe that information on the multiannual average monthly temperatures and the dynamics of multiannual monthly precipitation would be useful, to compare with the conditions in the year of the study, as well as information on the soil types in the four locations where the experiment was located.

In chapter 2.4. - Sample collection and biomass, details regarding the determination of leaf area and bibliographical specifications regarding the minimum number of plants required to determine morphological parameters such as plant height, stem diameter and others should be presented.

The results obtained are correctly interpreted, with clear expression, highlighting the effect that the altitudinal gradient, the cultivation method, exposure to total light, respectively partial shading and the harvest period had on the physiological and chemical parameters monitored in the Brachiaria brizantha species, in correlation with research previously carried out by different authors.

To substantiate the study, 56 references appropriate to the issues addressed were selected and used, although there are other relevant articles on this topic.

The table and figures presented in the manuscript are correctly elaborated and well-placed in the text, but in chapter 3.7. - Stomatal Morphometry, an error has recorded in when citing the figure, figure 4 with its components should be cited and not figure 3.

The conclusions drawn by the authors are consistent with the results obtained, but I believe that the effect of the altitudinal gradient should be better highlighted for a better agreement with the style of the manuscript.

In conclusion, with the clarifications requested above, with the small corrections and adjustments, I believe that the manuscript can follow the next editorial stages. It would be useful for agricultural practice in the area for the studies to be continued for at least two more years.

 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English expression allows understanding of the text, but it can be improved.

Author Response

Responses to Reviewer 1
Comment 1. Regarding the results, the soil class of each collection site along the topographic gradient studied should be specified. The authors could better explain the lack of difference in forage productivity and the variation in fertility between collection sites. Even though there was virtually no difference in forage production, a difference in its chemical composition was observed. Why did this occur? This should be detailed. The assertion that the Fabaceae family improves forage cannot, in my opinion, be confirmed by this study. For this, forage should have been collected from trees of only a few families and compared. Better use should be made of the results observed regarding the number and size of stomata and why this had no influence on the results obtained.
Response: The reviewer's recommendations were followed, the soil was classified according to its texture, and better use was made of the results, highlighted in the conclusions.
Responses to Reviewer 2
Comment 1. The manuscript addresses a relevant aspect of silvopasture systems applicable to management of similar tropical forage grasses. While the focus of the manuscript, as in title and study objective, is on physiological and chemical responses of Brachiaria Brizantha to environmental variations, the results and conclusions also address tree responses. May need to be modified to address both or be clarified.
Response: We have made the suggested change.
Line 77 – change with “this forage grass”
Comment 2. Table 4 “Which fiber category? are NDF and ADF not subcategories of fiber? If so how come their proportions are way larger than fiber?
Response: The reported NDF is between 60 to 75% which includes cellulose, hemicellulose and lignin, so it is higher. For SDF it is between 35 to 45%, because it excludes hemicellulose, so it is lower than NDF. Finally, Fiber is between 20 to 30% because it underestimates the total fiber, so its value is lower. Fiber is not currently reported in academic knowledge, but it is widely used by field technicians, so the authors consider that it should be kept in the article.
Responses to Reviewer 3
Line [199] - please give the temperature differences in degrees Celsius, not in %
Response: The reviewer's suggestion was complied with.
Line [201] – why such a low result for an altitude of 503 m above sea level for solar radiation decrease? Did the authors try to explain this in the Discussion? Fewer trees, smaller trees?
Response: The reviewer's suggestion was complied with.
Line [208] – in subsection 2.3 no information is given that pH, electrical conductivity, CaCO3 content, potassium content were determined. Please complete this. Specify by what methods.
Response: Added the methodology information for pH and EC observed by the reviewer.
Table 3 – what is MSD? In Tukey's test, HSD is counted. Are the results for altitude 503 and 661 for fresh matter and dry matter really well reported?. It is also strange that with such large differences in the obtained values, there was no statistical significance.
Response: MSD- Minimun Significant Difference, in Tukey's test
Please specify for which samples the results are given in Tables 3 and 4. For Brizantha in monoculture or for silvopastoral areas.
Response: They are indicated in parentheses in the first column of each table.
Table 4 – it is more correct to give the content of ingredients in g kg-1 rather than in %
Response: The authors want to keep the % since this information will also have a technical use for producers in the Peruvian Amazon. Since in the academy it can be easily transformed to g/kg by professionals with more specific knowledge.
Line [325] – Fig 4 not Fig.3, in linie [335] – Fig. 4F
Response: The order of the figures has been corrected
Please revise the Conclusion. In its current form, this is a shortened repetition of the results. Here there should be more generalized conclusions. Do the results have any practical significance? What other investigation should be performed?.
Response: The conclusions were improved
References need improvement, not provided as required by Agronomy
Response: The references were in accordance with the scientific journal's standards.
Responses to Reviewer 4
In Chapter 2.1. - Location of the study area: in order to have a much clearer presentation of the climatic conditions of the area, I believe that information on the multiannual average monthly temperatures and the dynamics of multiannual monthly precipitation would be useful, to compare with the conditions in the year of the study, as well as information on the soil types in the four locations where the experiment was located.
Response: These are areas that do not present climatic or edaphic information, because previously no academic studies were carried out.
In chapter 2.4. - Sample collection and biomass, details regarding the determination of leaf area and bibliographical specifications regarding the minimum number of plants required to determine morphological parameters such as plant height, stem diameter and others should be presented.
Response: Further details were added, as suggested.
The table and figures presented in the manuscript are correctly elaborated and well-placed in the text, but in chapter 3.7. - Stomatal Morphometry, an error has recorded in when citing the figure, figure 4 with its components should be cited and not figure 3.
Response: The order of the figures has been corrected
The conclusions drawn by the authors are consistent with the results obtained, but I believe that the effect of the altitudinal gradient should be better highlighted for a better agreement with the style of the manuscript.
Response: The conclusions were improved

Author Response File: Author Response.pdf