Contrasting Effects of NaCl and NaHCO3 Stresses on Seed Germination, Seedling Growth, Photosynthesis, and Osmoregulators of the Common Bean (Phaseolus vulgaris L.)
Round 1
Reviewer 1 Report
Comments to the manuscript entitled ‘Contrasting effects of NaCl and NaHCO3 stresses on seed germination, seedling growth, photosynthesis, and osmoregulators of the common bean (Phaseolus vulgaris L.)’ (Manuscript Number: agronomy-542963) written by Song Yu, Lihe Yu, Yulong Hou, Yifei Zhang, Wei Guo and Yingwen Xue.
General comments:
In the manuscript, authors compared effect of neutral and alkaline salt stress on plants what is the new approach in the study of plant responses to salinity stress. There are no doubts that experiments were executed carefully and a number of physiological and biochemical parameters were monitored. Manuscript contains some small errors shown as below.
Particular comments:
1. Abstract:
Line 22: Change ... this same effect. to ...the same effect.
2. Introduction:
Page 2, Lines 46-49: “............ nutrient imbalance, and membrane injury, have been studied in a range of plant...............” Something is missing (??)
3. Material and methods:
Page 3, Lines 127-130: How was pigment content calculated (what equations)?
Page 4, Line 151: Hamid et al. [32] is lacking in the reference list. Moreover, method of proline estimation, described in the manuscript, was originally described by Bates et al. 1973.
Page 4, Lines: 168-175: How glycine betaine was calculated (calibration curve?)
4. Results:
Page 9, Line 262: ... with the increase in concentrations... Concentrations of what?
Line 289: HPO4- or H2PO4-
Page 12, Lines 323-325: according to Figure 6D there is significant increase of proline at 30 and 60 mmol/L NaCl or there is error in chart description.
5. Discussion:
Page 14, Lines 404-405: ...accumulation of photosynthetic pigment content.... accumulation OR content
Page 15, Lines: 435-440: Try to explain why there is increase/decrease of Ca ions and decrease of Mg ions under applied stress conditions.
Lines: 437-438: ... at relatively high stress concentrations.... Something is missing (?), concentrations of what?
Line: 447: Change “stress concentration” to “stress conditions”
6. Table 2 and 3 captions: total determined molarity of what???
Author Response
1. Abstract: Line 22: Change ... this same effect. to ...the same effect. Response to the comment: Thank you for your comment. Accordingly, we have made the necessary change (page 1, line 23). 2.Introduction: Page 2, Lines 46-49: “............ nutrient imbalance, and membrane injury, have been studied in a range of plant...............” Something is missing (??) Response to the comment: Thank you for pointing this out. We have made the necessary changes (page 2, lines 57–58). 3.Material and methods: Page 3, Lines 127-130: How was pigment content calculated (what equations)? Response to the comment: The content of Chla, Chlb, and Car was calculated using the formulae of Lichtenthaler (1987): Chla = 12.25A663.2 - 2.79A646.8; Chlb = 21.50A646.8 - 5.10A663.2; Car = (1000A470 - 1.82Chla - 85.02Chlb) / 198. We have added this information in the manuscript (page 3, lines 269–271). Page 4, Line 151: Hamid et al. [32] is lacking in the reference list. Moreover, method of proline estimation, described in the manuscript, was originally described by Bates et al. 1973. Response to the comment: Thank you for the valuable comment. The reference for the determination of proline content has been revised per your comment (page 4, line 300). Page 4, Lines: 168-175: How glycine betaine was calculated (calibration curve?) Response to the comment: The content of glycine betaine was calculated using the reference standard for glycine betaine (50–200 mg·mL-1) (page 4, lines 325–326). 4.Results: Page 9, Line 262: ... with the increase in concentrations... Concentrations of what? Response to the comment: Thank you for your comment. We have revised the sentence “... with the increase in concentrations..” as “… with the increase in the concentration of NaCl or NaHCO3” (page 10, line 423). Line 289: HPO4- or H2PO4- Response to the comment: We apologise for overlooking this detail. We have replaced “HPO4-” with “H2PO4-” throughout the manuscript. Page 12, Lines 323-325: according to Figure 6D there is significant increase of proline at 30 and 60 mmol/L NaCl or there is error in chart description. Response to the comment: We apologise for overlooking this detail. You are correct; there was a mistake in Figure 6D (page 13, lines 461–462), which has been rectified (page 13). 5.Discussion: Page 14, Lines 404-405: ...accumulation of photosynthetic pigment content.... accumulation OR content Response to the comment: Thank you for the valuable comment. “…photosynthetic pigment content…” is correct; we have made the necessary changes in the manuscript (page 15, line 586). Page 15, Lines: 435-440: Try to explain why there is increase/decrease of Ca ions and decrease of Mg ions under applied stress conditions. Response to the comment: Explanation for the change in Ca2+ and Mg2+ concentrations caused by NaCl or NaHCO3 stress has been added (page 16, lines 628–644). Lines: 437-438: ... at relatively high stress concentrations.... Something is missing (?), concentrations of what? Response to the comment: We have revised the relevant sentence as follows: “…at relatively high salt concentrations (90–150 mmol·L-1 NaCl or NaHCO3 for the leaves and 90–150 mmol·L-1 NaCl or 120-150 mmol·L-1 NaHCO3 for the roots)…” (page 16, lines 634–636). Line: 447: Change “stress concentration” to “stress conditions” Response to the comment: We have replaced “stress concentration” with “salt concentration”. 6.Table 2 and 3 captions: total determined molarity of what??? Response to comment: It means the total determined osmoregulator molarity (page 18, lines 894 and 896)
Reviewer 2 Report
The authors present the results of an experiment in which they describe how common bean plants respond to two different stresses (NaCl and NaHCO3 stresses) on seedling and physiological parameters and osmoregulators. This work has an important innovative aspect since alkaline stress is not sufficiently studied in this specie and its response could provide a scientific basis for selective breeding and may help guide common bean production in salt-alkaline soil areas. For this reason, I think this work of interest.
On a general point of view, the text is generally readable and clear and the subject of the manuscript falls within the general scope of the journal.
Please have in consideration the following minor suggestions to improve the manuscript.
Introduction:
The response to common salt stress is well known, however the alkaline stress is not so much. Therefore, a greater bibliographic description of what is known of the response of the plant to this type of stress is required.
In my opinion, the objective is very general.
Material and methods:
I think it's better to call "C" to control rather than “CK” as it can lead to confusion with other parameters such as cytokinins (although in this work is not studied).
What is the capacity of the pots?
Results
The results are well described. However, the statistical analysis in the figures is not clear. On the one hand we must know the differences between the two stresses (saline and alkaline) and on the other the differences between different concentrations within a stress. This should be considered in the statistical analysis. In this way, for example, you could put asterisks if there are differences between the two stresses and letters according to differences between salt and alkaline concentrations individually.
Tables 2 and 3 have to be described in this section.
Discussion and conclusión
More discussion about the osmoregulators is missing.
The conclusion does not fully respond to the objective of the work: ‘The findings of the present study improve our understanding of the mechanisms involved in alkali stress (high pH) damage in common bean, provide a scientific basis for selective breeding and the promotion of saline-alkali-tolerant species, and may help guide common bean production in salt-alkaline soil areas’
Author Response
1.Introduction:
The response to common salt stress is well known, however the alkaline stress is not so much. Therefore, a greater bibliographic description of what is known of the response of the plant to this type of stress is required. In my opinion, the objective is very general.
Response to the comment:
Per your suggestion, we have supplemented the progress in research on alkaline salt stress in other plants (page 2, lines 66–73).
2.Material and methods:
I think it's better to call "C" to control rather than “CK” as it can lead to confusion with other parameters such as cytokinins (although in this work is not studied).
Response to the comment:
We have replaced “CK” with "C" throughout the manuscript.
What is the capacity of the pots?
Response to the comment:
Plastic pots (diameter: 25 cm, height: 25 cm, n = 220) were filled with washed sand (10 kg) (page 3, line 228).
3.Results
The results are well described. However, the statistical analysis in the figures is not clear. On the one hand we must know the differences between the two stresses (saline and alkaline) and on the other the differences between different concentrations within a stress. This should be considered in the statistical analysis. In this way, for example, you could put asterisks if there are differences between the two stresses and letters according to differences between salt and alkaline concentrations individually.
Tables 2 and 3 have to be described in this section.
Response to the comment:
We used the one-way ANOVA to analyse the data obtained from NaCl and NaHCO3 treatments. The letters in each figure indicate that the difference was significant between NaCl and NaHCO3 stresses at the same salinity or between different stress levels under the same stress type; therefore, we have not made any changes here.
We have added a description of results presented in Tables 2 and 3 in the results (page 14, lines 503–512).
4.Discussion and conclusión
More discussion about the osmoregulators is missing.
The conclusion does not fully respond to the objective of the work: ‘The findings of the present study improve our understanding of the mechanisms involved in alkali stress (high pH) damage in common bean, provide a scientific basis for selective breeding and the promotion of saline-alkali-tolerant species, and may help guide common bean production in salt-alkaline soil areas’.
Response to the comment:
Per your suggestion, we have added the discussion on osmotic regulators (pages 16–17, lines 689–789). The relationship between the results and objectives of the study has been demonstrated (page 17, lines 806–809)
