Effects of Different Forms of Tagetes erecta Biofumigation on the Growth of Apple Seedlings and Replanted Soil Microbial Environment
Round 1
Reviewer 1 Report
The MS described the alleviation of ARD by biofumigation with three different types of Tagetes erecta. This is a quite interesting work, to find a practical approach to deal with ARD problem will play important role in the sustainable develop of apple production. The authors have determined many parameters to find out the effects of T. erecta treatment. In principle the results are quite positive. Well-established methods are employed therefore the data are solid and convincing. However, there are two points which are not quite understandable for me.
1. For the treatments: DS was 6 g/kg, FS is 12 g/kg whereas IS was 16.7 g/kg. How the different amount for every treatment was selected? Normally the FW:DW is around 5-10:1, in this case, DS contains higher materials than FS, could this be the reason that DS works better?
2. T. erecta treatment increased the protective enzyme activity in root, what is the possible mechanism? Generally, protective enzymes are induced in response to increased biotic or abiotic stresses, in this experiment, adding T. erecta to soil alleviate the syndromes of ARD, indicating that the ARD stresses were reduced, then it is hard to understand the increase of protective enzyme activity inside the roots. This question should be discussed in “Discussion”.
Some details:
Abstracts:
1. What is CK1?
2. Add „in soils“ before „treated with T. erecta”.
3. What does „improved soil microbial community structure” means? I do not believe that there is a defined “microbial community structure” for apple.
Introduction:
1. What is “intensive development”?
2. Angus et al. (year) instead of reference number.
3. The effect of Tagetes erecta on apple replant disease has been published in 2019. (ACTA HORTICULTURAE SINICA ›› 2019, Vol. 46 ›› Issue (12): 2383-396. doi: 10.16420/j.issn.0513-353x.2018-0851)
Materials and methods:
1. Was soil enzyme activity determined with air-dried soils?
2. Were biomasses determined only in three plants?
3. Give citations to different microbe culture media.
4. qPCR program with an extension at 72°C?
results:
1. table 1, the letters for statistically analysis, for many factors have no a, starting from b, why?
2. Figure 1, the full name of Pn, Ci, Gs and Tr should be given in the legend and omitted in the figures.
3. Figure 6 is difficult to understand. the size of fragments is difficult to follow. Try to find another way to show the result more clearly. (one suggestion: set y axis as fragment sizes in block and use heatmap to show different percentages of every treatment).
4. Table 4, “JT”, typing error?
Discussion:
1. As suggested before, discuss the possible mechanism that the treatment increased the protective enzyme activity in root.
2. Explain and discuss the relationship among “microbial diversity index”, “Evenness index”, “Richness index”, “Simpson’s index” and ARD severity.
Author Response
Dear reviewer,
Thank you for your careful review of the article. We have carefully verified and modified each modification suggestion that you put forward.
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
The manuscript entitled "Effects of different forms of Tagetes erecta Biofumigation on the Growth of Apple Seedlings and Replanted Soil Microbial Environment" is interesting and may furnish new and important knowledge on biofumigation using T. erecta on the apple seedlings and to the replanted soil microbiome.
Nevertheless, the manuscript mainly lacks organization, writting and presentation and needs to be corrected as suggested.
All suggestions are marked on the manuscript.
Best Regards.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
Thank you for your careful review of the article. We have carefully verified and modified each modification suggestion you put forward. Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I am happy to read the revised MS and the reply to my comments. It is improved. Some minor points still need to address:
1. Line 24-26, change the sentence to : The activity of antioxidant enzyme including superoxide dismutase, peroxidase, and catalase were significantly increased in roots grown in soils treated with T. erecta.
2. Are you sure that the qPCR extension at 72°C? please check again carefully.
3. Line 345-347, It may be that T. erecta reduced the infection of pathogenic microorganisms in replant soil to the plant, thereby reducing the free radicals produced in the plant. This assumption is contradictory to antioxidant enzyme activity increase.
here the reference 22 and 23 are mixed.
Author Response
Dear reviewer,
Thank you again for your careful review of the article. We have carefully verified and modified each modification suggestion you put forward. Please see the attachment.
Author Response File: Author Response.docx
