Differential Physiological Traits, Ion Homeostasis and Cane Yield of Sub-Tropical Sugarcane Varieties in Response to Long-Term Salinity Stress

Round 1

Reviewer 1 Report

The authors tested nine different varieties under saline stress and determined which varieties are more suitable for this type of abiotic stress. There are a few points that the authors must fix before the document is ready to be accepted:

 

**Title: OK

**Keywords: OK

**Abstract: OK

**Introduction:

-The current flow is:

-Sugarcane economic importance and effect of abiotic stresses on yield, including salinity > Effect of salinity for sugarcane and examples of physiological disorders that happen in the sugarcane under saline stress and need to develop new sugarcane varieties with tolerance for saline soils and objective of this work.

The flow is not good. The authors are packing different ideas into one paragraph. Please, write one paragraph for each idea and avoid mixing ideas in the same paragraph. Therefore, I suggest the following flow:

-Sugarcane economic importance > Effects of abiotic stress on sugarcane yield > Salinity as an important factor of abiotic stress > Physiological disorders caused by salinity on sugarcane yield > Need to develop new sugarcane varieties with tolerance for saline soils > Objectives of this work

-Writing “tha-1” is not wrong, but I think it would be better if the authors write “t ha-1”.

-Please, define an abbreviation the first time that it is written in the text. After this, the authors can keep using the acronyms. For example, what is the meaning of EC, NMC, etc.?

**Materials and methods

-Please, do not provide results in the Materials and Methods section. Remove the reference of figure 1 from line 79.

-Please, provide pictures of the experimental setup, if possible.

-How did the authors make the replications? Did they plant 3 setts of each variety in one pot or did they use 3 pots with 1 sett of each variety? Or did they plant another number of setts per pot, using another number of pots per treatment? Please, make it clearer. Additionally, the authors may also use a flowchart to help make it clearer.

-Sugarcane setts are not germinated but planted until the plant is established. Germination is a phenomenon that happens only with seeds. Additionally, how long were the setts? There is no problem if their lengths were different, but please provide a range of lengths.

-Please, use “L” as an abbreviation for liter, not “l”.

**Results

-Line 105: Please, replace “that” for “which”.

-Figures 1, 2, 3, 4: Please, write in the captions of the figures the meaning of the error bars. Are they standard deviations of the three replications, standard errors, confidence intervals, etc.?

-I would like to suggest splitting the discussions into paragraphs, one paragraph per evaluated characteristic.

-Figure 3: What is the meaning of the “salinity treatment” on the right side of the graphic? If the authors want to present the combined results for the varieties, I suggest making another graphic for them.

-Figure 4: Please, add (a) and (b) for both graphs. Once again, if the authors want to present the combined results for the varieties, I suggest making another graphic for them. I think this type of graph is not important because it is expected that higher salinity stress will impact the physiology of the plants. The most important part of the work is to show the different behavior of different varieties and the focus must be on this point.

**Discussion

-Please, break the discussion into different paragraphs, one paragraph per idea.

-Please, beware of words sticking together. Add spaces between them, like “to” and “1800” (line 302) and “3.15” and “in” (line 351), for example.

-Line 303: In the current writing, the “550 mm of water” must be written without parentheses.

 **Conclusions: OK

**References:

-Please, avoid capitalizing the nouns of a title in an article even if it was published this way. Therefore, please write “Soil moisture deficit induced changes in antioxidative defense mechanism of sugarcane (Saccharum officinarum) varieties differing in maturity” instead of “Soil Moisture Deficit Induced Changes in Antioxidative Defense Mechanism of Sugarcane (Saccharum Officinarum) Varieties Differing in Maturity”.

 

**Supplementary material: OK

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Thanks to the authors for providing this study

This study provides practical information on: “Differential physiological traits, ion homeostasis and cane yield of sub-tropical sugarcane varieties in response to long-term salinity stress”.

 

General Comment: The results of the research are expected in advance: a salinity exceeding 4dS m-1 will cause a significant effect on physiological characteristics and decrease in productivity in addition to affecting the quality of soil and groundwater. However, please answer the comments below and clarify some of the queries.

 

In Abstract:

·       Starting with a short introduction of about two lines about the importance of study, for example, sugar cane, salinity, etc. Then write the study objective.

·       The abbreviation of displaying the results in the abstract in order to leave room to add a summary of the results of the study with the recommendation, which is not present in the current abstract.

In Introduction:

·       Line 53: Clarify this amount of water, 550 mm, per plant, per unit area, or during the period of the formative stage, and how long it lasts.. Explain that!!

·       Add in the introduction a paragraph on the effect of salt on the physiological characteristics of sugar cane, supported by the appropriate references. As well as another paragraph on the effect of salt on the gas exchange traits.

·        

 

In Materials and Methods:

·       Line 71: It is written 3 replications. and this is different from what is written in Abstract (5 replications) in line 15!! Which one is correct?

·       Are the developed genotypes used in the study compartmentalized in terms of their salt tolerance? Any Sensitive - Medium Sensitive - Salt Tolerant

·       What is the date of planting plants in pots? Where did you put the pots? Is it in direct field conditions or within a greenhouse, especially at the beginning of the experiment?

·       Add in table the physical specifications, chemical analysis and the percentage of organic matter in the soil that were placed in the pots, of course, before the start of the experiment.

·       Are the pots perforated from the bottom?

·       The pots are supposed to be perforated: What about the excess water that filters from the pots? Was it taken, and the salinity measured in it to find out how much salinity remained in the soil or was absorbed by the plant, which led to the different effects on the plant and the soil?

·       Important information about irrigation:

·       How was the irrigation done manually?

·       How often was the irrigation and to what stage?

·       What is the amount of watering per pot? How was it estimated?

·       What type of salt is used?

·       How was the salt solution prepared?

·       When was yield estimated? At what stage of the plant?

·       We want an illustration of the experiment in which the pots are clearly visible? a picture at the beginning of the experiment and another picture at the end. There is no need to add these images in the body of the text in the study.

In Results:

·       Put the results in paragraphs, not narration in this way, for easy access. Example: 3-1 Effect of irrigation water salinity on soil

            3-2 Effect of irrigation water salinity on genotypes survival rate

            Etc.……

·       Why was the control not added to figure 2 for comparison?

·       In Table 1, Cane length is not a physiological trait, but a morphological trait! Better to put it in a separate figure.

·       On the other hand, how was the plant length measured?

·       Did branches arise at the bottom of the plant? Was it taken into account when measuring height?

 

In Discussion:

·       Add a discussion of the results of the survival rate of sugarcane due to the effect of salinity as well as the effect of salinity on productivity (yield).

·       It is preferable to mention and discuss the environmental impact of the use of salt water, despite the tolerance of some genotypes to salinity.

In Conclusion:

·       Add a recommendation at the end of the summary conclusion.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Editor and Authors,

I read and revised with interest the manuscript entitled “Differential physiological traits, ion homeostasis and cane yield of sub-tropical sugarcane varieties in response to long-term salinity stress”. The manuscript is very interesting for studying the effect of salinity on the physiological parameters and yield of sugarcane varieties. In addition, the manuscript clarified very important points related to the salinity level and the effects on the different variables studied, being able to contribute to the advancement of information available in the literature in future studies on the subject in the world. However, some points need to be revised so that the manuscript can be finally approved. Some doubts and/or inconsistencies were pointed out and need to be reassessed by the authors.

The important points that deserve attention are:

- Materials and Methods: pag 2; line 86-90 “For analyzing Na+ and K+ content in different plant parts, 100 mg of oven dried and well ground plant material (roots and leaves) and 10 ml of juice extract was digested with 10 ml of HNO3:HClO4 (3:1) di-acid mixture and readings were taken with AAS (Systronics Flame Photometer 128).” It was not clear the period of conduct of the experimente and how long after the beginning of the application of the treatments that the evaluation was carried out.

- Pag. 2 line 92: change “… through Spahiro-Wilk” to “…through Shapiro-Wilk”;

- Results: Pag. 9 line 262 “Results of regression analysis indicated that 6 traits (Pn, E, NaR, NaJ, KJ and Juice Na/K) were unable to induce significant variation in the grain yield.”; Correct the text, as sugarcane does not produce grain. Or if it refers to literature, it should be referenced.

- Fig 1: The title of the figure is not self-explanatory, on the “y” axis it is referred to as buildup of salinity, but it seems that the value expressed is the electrical conductivity of the soil;

- Fig. 5: Legend of the “x” axis is overlapping the bars, the better the image presentation.

- Pag. 9 line 273: abbreviation “CY”, its meaning was not presented  and its unit was not informed;

- Pag. 10 line 276-281: “In addition, ranks were given to each sugarcane genotype based on predicted yield. Three genotypes, Co 0238, Co15027 and Co 0118 had relatively higher ranking and were identified as tolerant under salt stress (Supplementary table 4). Conversely, genotypes Co 05011, Co 06034 and Co 15023 had relatively lower ranking and thus, were found as sensitive to salt stress. The salt tolerant genotypes identified based on predictor traits of this model were similar to those which were identified based on actual cane yield.”; The authors claimed to find varieties that were tolerant and sensitive to saline stress, however, in my interpretation, the analysis performed simply allowed the identification of more or less sensitive varieties. No variety of sugarcane is tolerant enough to obtain satisfactory yields. As presented by the authors in the topic “conclusion”, ECiw ~8 and 12 dS m-1 were not suitable for sugarcane production, while 4 dS m-1 some varieties were able to survive, but were drastically addected by saline irrigation.

 - Conclusions: “Based on our results, Co 0238, Co 0118 and Co 98014 were tolerant to salinity stress by maintaining higher Pn, lower leaf Na+/K+ ratio, higher SCW and higher juice sucrose content.”; suggestion: to show more clearly that the varieties studied are susceptible, but that it was still possible to differentiate them in terms of saline stress.

Author Response

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Round 2

Reviewer 2 Report

Thanks to the authors for making the edit and responding to most comments.

Add responses to comments related to the Materials and Methods section (which have not been added)

Add the significant differences between the coefficients to the figures in the form of letters.

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Reviewer 3 Report

Dear Editors and Authors,

I view of the corrections they were satisfactory, considerably improving the understanding and quality of  the manuscript. Therefore, I am in favor of publishing the manuscrit "Differential pysiological traits, ion homeostasis and cane yield of sub-tropical sugarcane varieties in response to long-term salinity stress".

Kind regards,

Author Response

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