UAV-Derived Spectral Indices for the Evaluation of the Condition of Rye in Long-Term Field Experiments

Round 1

Reviewer 1 Report

This study concerns the effect of fertilization treatments on spectral vegetation indices. Even if I find the article interesting, the manuscript did not clearly deliver the information in research significance and experiments. The manuscript should be further revised to meet the quality of Agriculture.

Major comments:

1. The first paragraph in the introduction section is very long and needs to be shortened and divided into clear paragraphs. Better organization of the introduction section is needed.

2. The statistical analysis approach is not clear. The author should elaborate more on the ANOVA, and PCA approach, that is, how to use these methods to analyze the spectral data.

3. What is the relationship of the presented indices to plant growth? The author didn’t use any plant growth data in this study.

4. The authors showed some indices are affected by the fertilization, is this a positive affecting or a negative effect? 

Author Response

This study concerns the effect of fertilization treatments on spectral vegetation indices. Even if I find the article interesting, the manuscript did not clearly deliver the information in research significance and experiments. The manuscript should be further revised to meet the quality of Agriculture.

Authors: Thank you very much for all your comments

Major comments:

1. The first paragraph in the introduction section is very long and needs to be shortened and divided into clear paragraphs. Better organization of the introduction section is needed.

Authors: The Introduction was divided into paragraphs and some parts of the Introduction were shortened.

2. The statistical analysis approach is not clear. The author should elaborate more on the ANOVA, and PCA approach, that is, how to use these methods to analyze the spectral data.

 Authors: The chapter “2.3. Statistical analysis” was extended and description of the statistical methods applied in the study was clarified.

3. What is the relationship of the presented indices to plant growth? The author didn’t use any plant growth data in this study.

 Authors: In material and methods mean grain yield for recent 20 years was added and the same grain yield was added to PCA results which allow to evaluate relationships with grain yield which is most important agronomic trait of plant growth.

4. The authors showed some indices are affected by the fertilization, is this a positive affecting or a negative effect? 

Authors: Since higher values of most vegetation indices means better crop status, the increase of vegetation indices is usually positive, which was clarified in current version of the manuscript..

Reviewer 2 Report

The experimental work presented in the Manuscript, entitled „UAV derived spectral indices for the evaluation of the condition of rye in long-term field experiments " is interesting research with some promising results. The article reports the strongest effect on the   studied vegetation indices had nitrogen fertilization, which was much stronger than the effect of phosphorus and potassium fertilization. The treatments with nitrogen fertilization had significantly higher values of most vegetation indices in comparison to treatments without nitrogen, there are several shortcomings and modifications that should be included in order to enhance the final manuscript for the readers.

Lines 10 and 11. The treatments are not only potassium and phosphorus fertilization, but also nitrogen fertilizer.

Abstract is more description and it does not support by digital results and the important spectral indices which were selected in this study.

Abstract must be supported in the beginning by introduction as one sentence and at the end by the conclusion.

Line 33. Please add the citations at the end of the sentence.

In introduction section, please highlight what is the novelty (originality) of the work? And what is new in your work that makes a difference in the body of knowledge? What has been done that goes beyond the existing research.

The authors did not refer to the table 1 in the text.  

Line 119. Please , present the spectral indices which were tested in this study in table including the reference  and equation for each index.

Please give the reason why these spectral indices were tested in this study than other.

Please add one section in materials and methods about statistical analysis of the ground samples of plant and soils. The authors did not present anything about the values of N, P and k in the plant and soil samples.

The authors should present the range of N, P and k of plant samples at different growth stages with statistical analysis in section of the results.

The discussion is poor writing, I suggest to authors to divide the discussion section as results section or combined results and discussion in one section.

Please, write the practical applications of your work in a separate section, before the conclusions and provide your good perspectives.

Please write about the limitations of this work in details in conclusion section.

Author Response

The experimental work presented in the Manuscript, entitled „UAV derived spectral indices for the evaluation of the condition of rye in long-term field experiments " is interesting research with some promising results. The article reports the strongest effect on the   studied vegetation indices had nitrogen fertilization, which was much stronger than the effect of phosphorus and potassium fertilization. The treatments with nitrogen fertilization had significantly higher values of most vegetation indices in comparison to treatments without nitrogen, there are several shortcomings and modifications that should be included in order to enhance the final manuscript for the readers.

Authors: Thank you very much for all your comments

Lines 10 and 11. The treatments are not only potassium and phosphorus fertilization, but also nitrogen fertilizer.

Authors: Nitrogen has been added in this sentence.

Abstract is more description and it does not support by digital results and the important spectral indices which were selected in this study.

Abstract must be supported in the beginning by introduction as one sentence and at the end by the conclusion.

Authors: Abstract was improved according these comments.

Line 33. Please add the citations at the end of the sentence.

Authors: The citation is added to the end of the sentence.

In introduction section, please highlight what is the novelty (originality) of the work? And what is new in your work that makes a difference in the body of knowledge? What has been done that goes beyond the existing research.

Authors: We have added what is novelty of the study, i.e. novelty of the study is evaluation of relationships between K and P fertilization on the vegetation  indices because most of the studies focus only on nitrogen fertilization.

The authors did not refer to the table 1 in the text.

Authors: The reference to the Table 1 was added in the manuscript. Because one new table was added, the tables in the manuscript were renumbered.

Line 119. Please , present the spectral indices which were tested in this study in table including the reference  and equation for each index.

Authors: The vegetation indices were presented in the table.

Please give the reason why these spectral indices were tested in this study than other.

Authors: The vegetation indices were selected because are commonly used for evaluation of the crop status using remote sensing methods. Such explanation was added in material and methods.

Please add one section in materials and methods about statistical analysis of the ground samples of plant and soils. The authors did not present anything about the values of N, P and k in the plant and soil samples.

Authors: In the year of the study the soil and plant analyses were not conducted, however we have multiyear data which present content of potassium and phosphorus in soil as well soil pH. Content of available nitrogen is characterized by temporal changes with the vegetation season and was not presented. These results were included in material and methods.

The authors should present the range of N, P and k of plant samples at different growth stages with statistical analysis in section of the results.

Authors: We do not have such data and we cannot include these results in the manuscript. Instead of these data we have added table which presents phosphorus and potassium content in soil.

The discussion is poor writing, I suggest to authors to divide the discussion section as results section or combined results and discussion in one section.

Authors: The discussion was divided into sections and improved.

Please, write the practical applications of your work in a separate section, before the conclusions and provide your good perspectives.

Authors: Possible practical application of the results obtained in the study were presented in the end of the discussion.

Please write about the limitations of this work in details in conclusion section.

Authors: Limitation of the study were presented in the end of conclusions.

Round 2

Reviewer 1 Report

Author Response

Thank you very much for your positive opinion.

Reviewer 2 Report

abstract  still does not support by digital results and the important spectral indices which were selected in this study. As well as it  still does not support by in the beginning by introduction as one sentence.

 the authours  did not explaine about multivariate differences between treatments and relationships between vegetation indices in the section of discussion.

Author Response

abstract  still does not support by digital results and the important spectral indices which were selected in this study. As well as it  still does not support by in the beginning by introduction as one sentence.

Authors: Thank you very much for all the comments. Abstract was extended and changed and abbreviations were  clarified to underline more clearly the aim of the study, including significance of the spectral indices. In the introduction additional parts about spectral indices were added.

 the authours  did not explaine about multivariate differences between treatments and relationships between vegetation indices in the section of discussion.

Authors: In the discussion multivariate differences between the treatments and relationships between studied vegetation indices were better described.