Accumulation and Translocation of Phosphorus, Calcium, Magnesium, and Aluminum in Pinus massoniana Lamb. Seedlings Inoculated with Laccaria bicolor Growing in an Acidic Yellow Soil

Round 1

Reviewer 1 Report

The authors have presented the results of a study in which they field-tested the effects of ectomycorrhizal fungal (ECM) inoculation on the growth and uptake of aluminium (Al), phosphorus (P), calcium (Ca) and magnesium (Mg) in Pinus massoniana.  That the study was undertaken in a more naturalistic setting is important for gauging whether the greenhouse-observed effects of ECM on Al toxicity are indicative of field responses.  The results also have implications for widespread ECM inoculation of plantation pines in acidic soils.

While the study itself has largely been undertaken in a suitable manner (see pdf for minor comments and questions) and there are treatment effects, I am not convinced of the statistical differences between the Al treatments or between the ECM inoculation treatments.  This is because the statistics used do not appear to have been the most appropriate for the study. The data would be better analyzed using a two-way ANOVA, not univariate ANOVA. For example, I estimated the dry mass data from Figure 1, and found that the average biomass of the Al- treatments was marginally higher than the Al+ treatment.  Similarly, the three EC treatments all gave higher dry mass than the control, but it was unclear whether there were significant differences between them. There were no statistical results are provided (no statistical p values) given throughout the Results section that would’ve helped me work out treatment effects.

I would suggest that the authors re-analyze the data sets using two-way ANOVA and revise the data and Results section to focus on: 1) what is the difference between -Al and +Al treated seedlings, and 2) are there detectable differences between ECM treatments, and 3) do all ECM isolates show the same responses to Al treatments?  Analysing the results in this manner would indicate which factor(s) had the greatest influence on the plant responses and help to focus on the most interesting (clearly significant, interactive) aspects of the to present and address in the Results and Discussion. All other data can be presented in supplementary materials/ appendices.

Also, the level of ECM colonization in each treatment was assessed but the results not presented. Please provide these in the revised manuscript.  One other factor to consider: does the level of root colonization explain the levels of foliar nutrients?

Tables: The soil nutrient data may be better presented in a single table with the statistics added.

Figures: in their current form, the post-hoc test labels are hard to understand.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study investigated the accumulation and translocation of nutrients and aluminum in P. massoniana seedlings, inoculated with three L. bicolor strains, in an acidic soil in southwest China. This study is very interesting and provides novel findings on the role of ECM in plant nutrient uptake and metal tolerance. My overall suggestion is for major changes in the text to help the reader understand the main findings and take-home messages. I left several comments in the word document (attached) with suggestions to improve clarity. Consistency in using terms throughout the text should be taken into account, as well as the use of abbreviations. The authors should try and bring to light the most important findings and make it very easy to the reader to find them throughout the text. Also, I did not find any mention to supplementary material - maybe authors can include the rhizosphere soil pH data as supporting information to decrease the number of figures and shorten the main text.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I reviewed the previous version (R1) of the manuscript.

 

In reading this version of the manuscript, I find that the revisions have not been especially thorough. For example, there is no mention of statistical interactions between ECM inoculation source and Al addition; a two-way ANOVA would indicate such interactions. However, the results shown in Figure 2a and 3 indicate possible interactions because the inoculation sources provide different patterns of growth in -Al and +Al treatments.

Figure 1 and its description (and other figures/ descriptions) still do not make sense. The text has added a sentence or two to the existing material; I was asking for a clear re-write of the results. The only change in the Figure has been to remove the capital letters from the figure and add ‘P< 0.05’ to the text.  I was asking for the actual p values and preferably in a table or summary form.  In addition, the post-hoc test labelling still compares across all treatments even though there are differences within the -Al and +Al treatments; these differences should be tested separately. Finally, I had suggested that the biomass accumulation be analysed statistically to differentiate the contribution of each nutrient to the growth response. This has not been addressed.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf