Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this manuscript, the authors aimed to establish nutritional sufficiency ranges and critical levels for yerba mate to enable its foliar diagnosis. A total of 167 leaf samples were collected from production fields located in the five yerba mate-growing regions in Rio Grande do Sul, and leaf nutrients were analyzed. The work is interesting and useful. However, I have several points the authors may find beneficial. 

1. The abstract of the article does not specify the standard method for analyzing leaf nutrients.

2. The use of principal component analysis (PCA) is generally preceded by a test of the data to verify the suitability of the data for the use of PCA. KMO test and Bartlett's sphericity test are two important methods to assess the suitability of data before performing PCA. Please reconsider the methods in this manuscript. I suggest the authors can make more comprehensive overview on this point. The new work reported in recent years on PCA for element analysis could be included, e.g. DOI: 10.1007/s12043-023-02716-9, 10.1016/j.optlaseng.2023.107974. Meanwhile, the reasons or advantages for the chosen method in this manuscript was also not explained clearly.

3. The phrase "The nutrients with the highest imbalance were B, K, and Cu." in the abstract lacks clarity regarding the scope of its object.

4. The main research object of this paper is Yerba mate, and the keyword "Yerba mate" should be included. Please add it to the keywords.

5. The expression "167 yerba mate production fields" on line 141 is unclear. 167 refers to the number of leaf samples in the previous context, but here it seems to refer to the production sites.

Author Response

The authors would like to thank your valuable contribution.

We believe we made all alterations you suggested:

1. The abstract of the article does not specify the standard method for analyzing leaf nutrients.

R: We added the word ‘chemical’ to make it clear that we used standard chemical methods. However, we did not specify each method because the Abstract is limited to 200 words.

2. The use of principal component analysis (PCA) is generally preceded by a test of the data to verify the suitability of the data for the use of PCA. KMO test and Bartlett's sphericity test are two important methods to assess the suitability of data before performing PCA. Please reconsider the methods in this manuscript. I suggest the authors can make more comprehensive overview on this point. The new work reported in recent years on PCA for element analysis could be included, e.g. DOI: 10.1007/s12043-023-02716-9, 10.1016/j.optlaseng.2023.107974. Meanwhile, the reasons or advantages for the chosen method in this manuscript was also not explained clearly.

R: We tested our dataset, as suggested (lines 136 to 139)

We included recent work with PCA and explained the rationale of the technique.

3. The phrase "The nutrients with the highest imbalance were B, K, and Cu." in the abstract lacks clarity regarding the scope of its object.

R: We deleted the phrase.

4. The main research object of this paper is Yerba mate, and the keyword "Yerba mate" should be included. Please add it to the keywords.

R: We included the keyword now.

5. The expression "167 yerba mate production fields" on line 141 is unclear. 167 refers to the number of leaf samples in the previous context, but here it seems to refer to the production sites.

R: Each sample corresponded to one different production field. We changed lines 80 and 146 (formerly 141) to make it clearer.

Reviewer 2 Report

Comments and Suggestions for Authors In my opinion and considering that the manuscript was submitted to the special issue Integrated Management and Efficient Use of Nutrients in Crop Systems, the work does not contribute significantly neither to integrated management nor efficient use of nutrients. It reports a multivariate compositional nutrient diagnosis standard, and that there was no positive correlation between any single nutrient and yield. In general, there is an agreement that high-yield production is the result of multiple interaction among nutrients. In this sense, the manuscript does not contribute with novel features. The manuscript resembles more a technical report describing the imbalance in B, K and Cu (without any correlation with location, soil conditions, kind, or frequency of additives) but not any comments regarding management or efficient use of nutrients. The manuscript is technically correct, and the results could be of interest, but it seems more a technical report that a research paper.

 

 

 

Author Response

We thank the reviewer and respect the evaluation. However, we humbly disagree with it.

First, we submitted the manuscript to this special issue because it was indicated to us by the Agriculture editorial board. We submitted the abstract, and Agriculture indicated this issue as the most adequate.

Anyway, we believe that the manuscript contributes effectively to the efficient use of nutrients since it defines, for the first time, the critical levels and sufficiency ranges for leaf nutrient diagnosis of yerba mate. Until now, there were no parameters to evaluate the nutritional status of this crop, which is so important to the culture and economy of South America. We also have to say that we related the imbalance in B, K, and Cu with soil traits, with emphasis on the parent matter of the soils in which the plant is grown.

We believe our manuscript is like many other research papers (not technical reports), including several that we cited, which used CND to define critical levels and sufficiency ranges for different crops.

We hope you reconsider your opinion and accept this research paper.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

In opinion of this reviewer, the manuscript revised sent, was not substantially modified comparing with the original version. As mentioned, in my opinion, the manuscript discusses more a method than the composition itself. As a proof of concept, the conclusions are:

The CNDr² indices were effective in establishing the critical levels, sufficiency ranges, and nutritional status of yerba mate concerning the leaf concentration of the nutrients at deficiency, balance, and excess concentrations.

The CND methodology identified adequate nutrient levels in the leaves, which contributes to establishing the actual need for fertilizer application in yerba mate production fields.

Multi-nutrient associations were found to be more effective than single-nutrient analysis in highlighting the impact of a certain nutrient limitation on the productivity of yerba mate production fields.

A more appropriate title for the manuscript perhaps could be:

CND methodology and its effectiveness to identify nutrient levels in Yerba mate.

Author Response

We thank the reviewer for the valuable contributions. We have changed the title as suggested.