Biochar Application: A Viable and Pyrolysis Temperature Dependent Option for Enhancing Leaf Secondary Metabolites of Cyclocarya paliurus

Round 1

Reviewer 1 Report

Journal: Forests

Manuscript ID: forests-2444730

Title: Biochar application: a viable and pyrolysis temperature dependent option for enhancing leaf secondary metabolites of Cyclocarya paliurus

Li et al. presented a study dealing with biochars obtained by pyrolysis of poplar sawdust at 350 ℃ (C350) and 600 ℃ (C600) and their application as auxiliary substrate material for the cultivation of Cyclocarya paliurus seedlings in the greenhouse. The aim was to study biochar's effects on soil properties, seedling growth, and the accumulation of main secondary metabolites in C. paliurus leaves. The manuscript is very interesting. It is also well-prepared. It fits well with the scope of the Journal. I have only a few minor comments. They are listed below.

The abstract is suitable but may be too long. The authors should try to condense it.

The introduction is informative and detailed enough. Still, the novelty of the paper is not clearly stated, so it should be added at the end of the Introduction along with the motivation for the manuscript.

Materials and Methods are very well written and explained in detail.

The results are carefully presented and meaningful.

Table 1 – please, add the explanation for a,b,c.

The authors should present a chromatogram of the leaf extract.

The discussion is thorough and given with respect to the existing literature.

The conclusions are in line with the results, but in my opinion, they should be given in a separate section.

The literature is up-to-date.

Minor editing of English language is required.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors, despite the potential of the manuscript, the approach to the data used is wrong, the authors have little degrees of freedom  to compare the results, thus the inferences of the data are compromised by the low power of the anova and the test of means applied. Below are some considerations:

- The abstract of the manuscript is extensive, the authors can be more concise in it.

- The introduction is ok, however the hypothesis must come before the aims in the work.

- In the biochar synthesis part, more information must be provided, such as the heating rate, and the time of pyrolysis, as this affects the properties of the produced biochar.

- In the statistical approach there is a serious error that can compromise the quality of the data generated, the authors have three treatments that were repeated in 3 blocks, however much each block contains more plants (containers), the experimental unit of the authors is the treatment together with the respective block, so the degrees of freedom of the residues in the anova is only 4, and the minimum acceptable with some exceptions is 12. Also because the authors join the samples of the containers to make a composite sample. Thus, this number of degrees of freedom of the residue limits all inferences of the data, because with such a low degree of freedom, the power of the anova and the applied tests is limited. There are some cases in which the authors compared two evaluation times (2 months), in which case the degree of freedom increases, however there is a correct way to compare the data is in a split plot scheme, since the authors do not use this approach. 

- The statistical approach and design of experiment is wrong!

- Figure 5 is interesting, but uninformative comparing different treatments, as there is no statistical test applied to it.

- The discussion is ok, however the discussion paragraphs are long, could be more concise, or could be split.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear Editor and authors

Even though the experiment was completely randomized desing, the degree of freedom in ANOVA is still low, less than 12, which compromises the quality of the data produced. The authors should do another round of review again, making these points clearer, I suggest that he put the table of the summary of the analysis of variance as a supplementary document of the article, so that he can judge the quality of the data produced. The other suggestions were accepted by the authors.

Author Response

Please see the attachment.

Author Response File: Author Response.docx