Metal Accumulation and Tolerance of Energy Willow to Copper and Nickel under Simulated Drought Conditions

Round 1

Reviewer 1 Report

The authors have produced interesting results that collectively point to flexible adaptive capabilities of the electric willow cultivar under study to cope with contamination with copper or nickel per se or in a combination with simulated drought. Furthermore, results of this study have provided a deep insight into scenarios of willow development and physiology after stresses caused by some metals and/or drought. In relevance to environmental aspects, the produced results are useful for general recommendations of the studied willow variety for cultivations in nickel-contaminated soils and\or in locations where drought is common. This manuscript meets the topics of Sustainability journal but should substantially be overworked in view of numerous comments as below.

Abstract should be focused more than in its original version on the major results and their significance, instead descriptions of experimental design. In the beginning the authors should outline the background and why they have undertaken this study.

Unfortunately, the authors could not describe in their ms the originality of this study, the major leitmotif, and the importance of the produced results, paying too much attention on why energy willow is useful and too little about physiology in Introduction

Overall, the Introduction is too long and has yet provided general and unnecessary information. Indeed, this part should be written in a concentrated form. It is too obvious that “Nowadays, we are facing challenges in the field of energy and environmental protection [1].

It is unnecessary to explain an obvious fact that drought is the main abiotic and common stress… (LL 65-72).

The reference should be given just after “During drought stress, the plant reduces the expression of genes responsible for photosynthesis, while induces the expression of genes responsible for the synthesis of ABA, osmoprotectants, metabolites protecting against the formation of reactive oxygen species (including phenolic compounds), signaling genes that increase sensitivity to abscisic acid”.

Instead of general information, the authors should provide the analysis of relevant literature and preceding works, before the main goal and explain whether similar investigations had been carried out.

It is a great omission that the authors have not indicated how representative samples were prepared and analyzed for roots or shoots.

The choice of PAG-600 to simulate the drought stress should be explained more than in L97-8.

Noteworthy, AAS-based measurements of elemental composition require many subsamples for a given sample in view of expectable significant variations.  Are three measurements enough?

What were basic standards for calibration curves? (LL 140-1)

 The authors have not explained why 1 mM concentration of metal cations has been used? What are maximum permissible levels?

Generally, the authors have provided too long description for their results that can easily be seen from figures. So far, it is difficult to extract valuable information from vague descriptions. I recommend reducing mentioning of ‘no effect’ cases and concentrating on most important and statistically significant differences between control and experimental groups.

Similarly, it is redundant to place all numerical data in the text – they are visible in plots.

Some figures can be moved to Supplementary material

It is not correct to claim here (L 242) that “nickel addition accompanied by simulated drought conditions strongly induced nickel transport” A term “induce” is generally pertaining to switching of a process. Otherwise explain please how an elevated Ni level with drought could stimulate the transport. Or whether drought has facilitated Ni entering? How?

PCA is important but cannot prove, for example, Ni-induced stimulation.

Again, any statements like “Iron content in willow organs was greatly depleted by metals” should carefully be checked. As with this example one may conclude that metals directly deplete the content but it has not strictly been proved. It much more correct to write than in original text that addition of metals was accompanied with depletion. It is an example of what should be subjected to corrections through the text.

Discussion should be more balances with the produced results. A paragraph in LL353-60 gives too general information and should be omitted. Lines 361-5 are for Introduction.

Both the novelty and importance of the data obtained should be highlighted in Discussion more than in the original ms. It can be useful to reflect here whether similar investigations were conducted with other willow cultivars or species. I don’t rule out that this comprehensive study was conducted for the first time.

English should be improved.

In several places, another term should be used, such as cultivar, instead of variety, having plural meanings in biology. Variety is OK in the description of the plant studied.

L30 plants, not plant

Please explain “without rods” (L200 )

AAS, not ASA must be used for atomic absorption spectrophotometry

Avoid using single nouns for samples. For example, the middle leaf of each plant was weighed. One leaf?

Constructions “isolated treatment” have confusingly been used. Why not to write treatment with Cu or Ni? Generally, it is recommended to remove “isolated”, “comparable”, applied and other redundant definitions to treatments

comparable as -> compared to

English should be improved according to my comments.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thank you for giving me the opportunity to revise the MS entitled “Metal accumulation and tolerance of energy willow to copper and nickel under simulated drought conditions” by Kinga Drzewiecka and his/her colleagues that was submitted to “sustainability”. The MS submitted is suitable for sustainability, and some interesting results were showed. However, there are several requirements that have to consider by the authors. In this regard, the following comments are requested to be addressed by the authors:

 

1.         The Abstract section are not refined enough and needs to be carefully revised.

2.         Please modify and delete unnecessary keywords, Add some relevant keywords.

3.         I think the introduction section should be revised better. the innovation of the manuscript must be clearly stated in the text.

4.         Why choose two heavy metals, Cu and Zn, without considering other heavy metals such as cadmium.

5.         What is the initial concentration of heavy metals in the experimental simulation? Why use this concentration value?

6.         Please add some discussion and research on the mechanism.

7.         Please note that the format of references must be uniform. And some references are too outdated

I would suggest that the authors review and include the following recent studies to improve the manuscript.

a.       Organic–inorganic composite modifiers enhance restoration potential of Nerium oleander L. to lead–zinc tailing: application of phytoremediation. Environ Sci Pollut R 2023, 30, 56569-56579.

b.      Lead Responses and Tolerance Mechanisms of Koelreuteria paniculata: A Newly Potential Plant for Sustainable Phytoremediation of Pb-Contaminated Soil. Int. J. Environ. Res. Public Health 2022, 19, 14968.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Please revise the Discussion Part. It is quite short and not strongly relevant to the study. 

Comments for author File: Comments.pdf

There are still a lot of typos. Some paragraphs are not clear and need to be rewritten.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I have no further comments, except for minor corrections as beow. 

 

A subsamples should be corrected

Reviewer 2 Report

ok to accept.