Phosphate Uptake is Correlated with the Root Length of Celery Plants Following the Association between Arbuscular Mycorrhizal Fungi, Pseudomonas sp. and Biochar with Different Phosphate Fertilization Levels

Round 1

Reviewer 1 Report

The authors did not demonstrate detailed methods for measuring colonization of AM fungi rate, but only cited only the referece `Phillips and Hayman(1970)` in the method part. The reference is too old to find it. The authors must demonstrate even briefly how they performed in their expereiment and also state especially how to generate(calculate) the percenetatge for the rate in their experiment. 

Author Response

Thank very much for your suggestion. 

We corrected this part.

Please see L161-166.

Author Response File: Author Response.doc

Reviewer 2 Report

Review Ning et al.

 

General comments

The study presented describes the interactive effects of arbuscular mycorrhizal fungi, a Pseudomonas strain and biochar amendments on the growth of celery plants under different conditions. Especially the testing of the three factors together is novel, and the findings of strong effects of the combination of them will be relevant for their application. Also, the differential results depending on substrate and P availability allow to understand the relevance of such growth amendments as an alternative to fertilizers. The many factors in one study also allow to compare actual effect sizes of each factor, which is rarely possible. The study is well written and methods and results solidly presented.

I was just a bit confused about the analyses. Looking at the results, it seems to be a simple univariate analysis of variances, comparing the different treatments among each other. Regarding the quite clear results this may even be sufficient. However, in the methods part authors claim to do three way analyses of variances. First, the design does not allow for such analyses since it is not fully factorial (Pseudomonas was not paired with biochar). And second there is no result based on such factorial analyses presented, only univariate comparisons. So authors should be clear in their description of statistics. And may consider to add a test on interactive effects of AM and biochar and AM and Pseudomonas, and consequently also the effect of AM and biochar overall, which will give more statistical power to the analysis. However, in case of interactive effects the interpretation of each factor alone is difficult. So I would recommend either way to keep the univariate analyses, even if only for the figures.

Another general comment: Throughout the introduction and discussion it is often unclear whether statements refer to this study system, or the cited study given in brackets. Please be more specific when referring to details from another study. I provide more specific comments below.

 

Specific comments:

L41/42 this sentence does not make sense, please rephrase

L46-52 please clarify whether Pseudomonas is a symbiont of AM fungi, or of the plant. Where is it located, within hyphae or also within roots, interacting with hyphae there?

L58 The transitions in the introduction are partly a bit too drastic. Maybe start this paragraph for example with a short sentence on the general significance of biochar, and how it relates to microbes discussed in the section above.

L71/72 In which system?

L106 Please mention the origin of those inocula of AMF and Pseudomonas.

L113 Inactivated by autoclaving?

L132 What means 8 weeks after transplanting? Please describe the time spans and study design in more detail if transplanting was involved

L137/138 Is there a reference for this program?

L139/140 Which stain was used, how many intersects counted at which magnification? Or is this clear from the reference?

L151-157 The many numbers given are not necessary, since they can be seen from graphs and tables. One example of effect sizes is enough. I would rather recommend to state the general main effects and refer to the figures for the detailed numbers.

L188 different means reduced?

L190/191 But biomass did increase in those treatments? I do not understand this sentence then

L215 Please start this sentence differently, like root colonization was…

Was colonization in the control also counted? Please shortly state the presence (or not) of “background” colonization

L232 It feels weird the discussion starts with a detailed discussion about root traits, while biomass seems more relevant as response variable. Maybe it would help to start with a more general summary of the most relevant findings, and then discuss these details.

L243-247 Here it must be indicated clearly which findings are reported. E.g. Olmo et al. (2016) found in their study on… to make clear that results from other studies are discussed, and not findings presented here

L308 Was N available in sufficient amounts? Is it possible to say in the methods or here whether the results were observed under N limiting conditions, or fertilization was quite high and no limitation by other elements than P was likely?

L333-337 again indicate references better

Author Response

Dear reviewer,

Thank you very much for your responses. We responsed all your comments and questions and corrected. Please see the items below in this text in dark writing. And also the manuscript of revised version.

Afterwards we think it is much better than the submitted version.

Best regards

Zhifang

 

General comments

The study presented describes the interactive effects of arbuscular mycorrhizal fungi, aPseudomonas strain and biochar amendments on the growth of celery plants under different conditions. Especially the testing of the three factors together is novel, and the findings of strong effects of the combination of them will be relevant for their application. Also, the differential results depending on substrate and P availability allow to understand the relevance of such growth amendments as an alternative to fertilizers. The many factors in one study also allow to compare actual effect sizes of each factor, which is rarely possible. The study is well written and methods and results solidly presented.

I was just a bit confused about the analyses. Looking at the results, it seems to be a simple univariate analysis of variances, comparing the different treatments among each other. Regarding the quite clear results this may even be sufficient. However, in the methods part authors claim to do three way analyses of variances. First, the design does not allow for such analyses since it is not fully factorial (Pseudomonas was not paired with biochar). And second there is no result based on such factorial analyses presented, only univariate comparisons. So authors should be clear in their description of statistics. And may consider to add a test on interactive effects of AM and biochar and AM and Pseudomonas, and consequently also the effect of AM and biochar overall, which will give more statistical power to the analysis. However, in case of interactive effects the interpretation of each factor alone is difficult. So I would recommend either way to keep the univariate analyses, even if only for the figures.

Corrected, please see L170-172.

Another general comment: Throughout the introduction and discussion it is often unclear whether statements refer to this study system, or the cited study given in brackets. Please be more specific when referring to details from another study. I provide more specific comments below.

 Corrected, and several references were added.

 

Specific comments:

L41/42 this sentence does not make sense, please rephrase Deleted, L41.

L46-52 please clarify whether Pseudomonas is a symbiont of AM fungi, or of the plant. Where is it located, within hyphae or also within roots, interacting with hyphae there? Corrected L46-53.

L58 The transitions in the introduction are partly a bit too drastic. Maybe start this paragraph for example with a short sentence on the general significance of biochar, and how it relates to microbes discussed in the section above. Corrected L59-60.

 

L71/72 In which system? Deleted “system” L72

L106 Please mention the origin of those inocula of AMF and Pseudomonas. Corrected, L124 and L127.

L113 Inactivated by autoclaving? Corrected, L115.

L132 What means 8 weeks after transplanting? Please describe the time spans and study design in more detail if transplanting was involved. Corrected L134-135.

L137/138 Is there a reference for this program? Corrected L142.

L139/140 Which stain was used, how many intersects counted at which magnification? Or is this clear from the reference? Corrected L161-166.

L151-157 The many numbers given are not necessary, since they can be seen from graphs and tables. One example of effect sizes is enough. I would rather recommend to state the general main effects and refer to the figures for the detailed numbers. Corrected, L178-183.

L188 different means reduced? Corrected, L230-231.

L190/191 But biomass did increase in those treatments? I do not understand this sentence then. L232, with soil condition, both N concentration and biomass were not statistic significant, but the uptake of N and P were significant increased. This was due to the accumulation increase of concentration and biomass. -

L215 Please start this sentence differently, like root colonization was…Corrected L263-264.

Was colonization in the control also counted? Please shortly state the presence (or not) of “background” colonization

L232 It feels weird the discussion starts with a detailed discussion about root traits, while biomass seems more relevant as response variable. Maybe it would help to start with a more general summary of the most relevant findings, and then discuss these details.

Corrected L285-286

L243-247 Here it must be indicated clearly which findings are reported. E.g. Olmo et al. (2016) found in their study on… to make clear that results from other studies are discussed, and not findings presented here. Corrected L303.

L308 Was N available in sufficient amounts? Is it possible to say in the methods or here whether the results were observed under N limiting conditions, or fertilization was quite high and no limitation by other elements than P was likely? Corrected L373.

L333-337 again indicate references better. Corrected L400.

 

 

 

 

 

 

 

 

 

Author Response File: Author Response.doc