Changes in Leaf Structure and Chemical Compositions Investigated by FTIR Are Correlated with Different Low Potassium Adaptation of Two Cotton Genotypes
Round 1
Reviewer 1 Report
Potassium is one of the essential mineral nutrient for growth and development of plants. Plays a vital role in activating enzymes systems, photosynthesis, is required for optimal protein synthesis. Chemical fertilizer is ensure an adequate supply of available K to crops in intensive agriculture. Mineral fertilization may improve absorption of potassium and prevent nitrogen and other deficency nutrients and provide a nutrient balance in crop development.
Therefore studies on the influence of mineral nutrition on the physiological quality of leaf structure and chemical compositions of the two different cotton genotypes are still required. Thus the topic of this paper is of importance when considering the fact that studies are essential to understand the effect of different management practices on soil and plant system. In addition the topic is closely falls within the aims and scope of the journal. Material and methods need some modifications. The treatment of macronutrients in the hydroponically in a nutrient solution should be present in table. The data provided are sufficient and the statistical analysis of the results is very well presented. Figures clearly present the data. The discussion of results focus on the main points while justification of the findings are well supported by references.
The results are too general. Prince there is no control group in the experience, it should be stated in the conclusions that there is less (or more) in some component compared to plants from a particular genotype. There are too many generalizations used in the work. The authors should write about the influence of the examined factors on the tested parameters.
In some places (for example line 84, 139, 157, 159) superscript should be used.
Author Response
1. Potassium is one of the essential mineral nutrients for growth and development of plants. Plays a vital role in activating enzymes systems, photosynthesis, is required for optimal protein synthesis. Chemical fertilizer is ensured an adequate supply of available K to crops in intensive agriculture. Mineral fertilization may improve absorption of potassium and prevent nitrogen and other deficiency nutrients and provide a nutrient balance in crop development. Therefore studies on the influence of mineral nutrition on the physiological quality of leaf structure and chemical compositions of the two different cotton genotypes are still required. Thus the topic of this paper is of importance when considering the fact that studies are essential to understand the effect of different management practices on soil and plant system. In addition the topic is closely falls within the aims and scope of the journal. Material and methods need some modifications. The treatment of macronutrients in the hydroponically in a nutrient solution should be present in table. The data provided are sufficient and the statistical analysis of the results is very well presented. Figures clearly present the data. The discussion of results focus on the main points while justification of the findings are well supported by references.
Response: Thank you very much for your kind words and helpful comments. According to your suggestion, the “Material and methods” section has been revised with some modifications, and the nutrients in the hydroponically in a nutrient solution now are presented in Table 1.
2. The results are too general. Prince there is no control group in the experience, it should be stated in the conclusions that there is less (or more) in some component compared to plants from a particular genotype. There are too many generalizations used in the work. The authors should write about the influence of the examined factors on the tested parameters.
Response: Based on your worthy comments, we have carefully revised the “Results” section with deleting some generalizations and writing more contexts about the influence of the examined factors on the tested parameters. We hope you will be satisfied with our modification. Thank you.
3. In some places (for example line 84, 139, 157, and 159) superscript should be used.
Response: In revised manuscript, superscript has been used in corresponding places (for example line 84, 139, 157 and 159).
Reviewer 2 Report
Overall good paper with interesting subject matter. Authors do a good job of presenting most methods and results, although some areas could use clarification or simplification to reach a broader audience. These have been noted in the track changes version attached.
Grammar is mostly good although there are some cases where phrasing is awkward or sentences should be re-worded. These have also been identified in the attached track changes version.
Check the means separation letters in Figure 1B, appears to be an error here that is noted in the track changes version.
Comments for author File: 
Comments.pdf
Author Response
Commented [A1]: Would there be a better term to use here besides “seriously” and “more serious”? Maybe “slightly” and “greatly”, or something along those lines that expresses magnitude.
Response: Thank you for your good suggestion. The sentence has been improved to: “…protein and polysaccharides of leaf were greatly influenced by K deficiency, and the changes were more significant in leaf of genotype-122 …”
Commented [A2]: Is there a more up to date statistic?
Response: We have thoroughly checked the papers of last few years, and we cited the new data about the K fertilizer demand in the world reported by the Food and Agriculture Organization of the United Nations (FAO) in revised manuscript as bellow: “According to the data of the Food and Agriculture Organization of the United Nations (FAO), the global K fertilizer demand has reached 68 (Mt) in 2019.”.
Commented [A3]: K efficiency levels?
Response: Yes. It has been corrected.
Commented [A4]: Vast? Plethora?
Response: The “huge” in here was used to mean “many”, it is an inappropriate word, and we have changed it by “a lot of”.
Commented [A5]: This phrase is a bit awkward, perhaps: Once the radicle had reached at least 1 cm in length…..
Response: We have modified this phrase as your suggestion.
Commented [A6]: So each bucket contained all three reps of one treatment? Or were they transplanted again, and that’s what you’re referring to as “cultivated hydroponically” Could use clarification of how you go from the 3 seedlings per bucket stage to each seedling become a replication.
Response: We appreciate you raised the mistake in the original manuscript. In the experiment, three seedlings were cultured in each bucket and they were harvested as one replication at the end of the experiment. We conducted four treatments (2 K levels×2 varieties) and five buckets (five replications) in one treatment. To make the design easier to understand, the mistake has been corrected and this section has been rewrite to: “The experiment had a completely randomized design with four treatments (2 K levels×2 varieties), each treatment consists five buckets (five replications) and the three seedlings cultured in the same bucket were defined as one replication.”
Commented [A7]: Leaf samples were dried to a constant weight at 75°C then ground to a fine powder.
Response: This sentence has been revised to “Leaf samples were dried to a constant weight (all the water in leaves was removed and the dry weight of leaves would not decrease with additional drying) at 75°C then ground to a fine powder.”
Commented [A8]: What do you mean by “constant weight”? I’m assuming you mean you dried them until they reached the point that additional drying would not decrease the mass, i.e. all the water weight was removed. The term “constant weight” may be confusing for some readers initially, so perhaps there’s a way to clarify?
Response: “constant weight” means the leaves are dried to remove all the water and the dry mass of leaves would not change with additional drying. To make it easier to understand, we have clarified it in the above sentence.
Commented [A9]: cm-1 (superscript the -1 throughout when using it in this method)
Response: All the “-1” in our manuscript have been superscripted based on your worthy comments.
Commented [A10]: Fig. 1B – it appears that you performed means separation within each plant part and not across. However, in roots you have a means separation letter of bc for 122K1, but there is no main effect with c alone, thus (unless I am mistaken), this should either be a “b” or a “c” but it can not be labeled as bc.
Response: Thank you for pointing out this mistake, we have carefully checked the data and conducted the variance analysis again, “bc” should be “b” and we have modified it in revised figure.
Commented [A11]: Excellent explanation!
Response: Thank you.
Commented [A12]: Should the text in the columns be centered under their respective headers, since the headers are centered? Also, would it be a good addition to add a column for impact or effect of lower peaks for each of these categories, i.e. the physiological effects of this? Not necessary but just a thought to make this table more impactful.
Response: According to your comment on the table, the text in the columns has been centered under their respective headers. What is more, a new column that indicates physiological effects of different peaks also has been added in tables. Thank you for raising the good suggestion.
Commented [A13]: Could you add a sentence or two with a simplified explanation of what you’re presenting here? The impact or point was not easily understood after the first time readier this, particularly for an audience not as familiar with FTIR spectra or absorption data.
Response: New information about semi-quantitative analysis has been provided and we revised the section as bellow: “Semi-quantitative analysis is a common method in FTIR to eliminate the differences caused by sample quantity and indicate the repeatability of the spectra in one treatment. The semi-quantitative analysis also can be calculated to analyze the changes in main absorption bands corresponding to functional group from chemical composition in the functional leaf under low K. The results suggest that…” Now this part is clearer and easier to understand.
Commented [A14]: How about: Potassium is an essential macronutrient that participates in the activation of various enzymes and protein synthesis in plants and promotes transport of soluble substances in the xylem and phloem.
Response: Thank you for your nice suggestion and we have modified the sentence in revision.
Commented [A15]: Isn’t 122 the K inefficient genotype? Also, it doesn’t appear that the low K supply reduced the intensity at 1384 a large amount between the two genotypes, but perhaps than more to this number than just looking across the y-axis. Visually it doesn’t appear to be a big difference so could you expound on this difference a bit more?
Response: Yes, 122 is the K inefficient genotype, and we have corrected it. In the original manuscript, we compared the changes on the intensity of peak at 1384cm-1 (y-axis) and the intensity of 103K1, 103K2, 122K1 and 122K2 are 0.41, 0.55, 0.34 and 0.52, respectively. Comparing to K2 treatments, 103 and 122 are decreased 0.14 (0.55-0.41) and 0.18 (0.52-0.34) by K deficiency, indicating that the K deficiency-induced decrease on the intensity at 1384 cm-1 in K-inefficient genotype 122. In fact, we also can conclude that K deficiency has greater effect on peak at 1384 cm-1 in K-inefficient genotype 122 by observing the smoothness of the peak at 1384cm -1. It is obviously this peak of 103K1, 103K2, 122K2 are very sharp, while this peak of 122K1 is very smooth, suggesting that K deficiency weakened vibration of the peak of 122K2, to a greater extent. To discuss the results more rigorous, we have rewrite the section in the revised manuscript. We hope you will be satisfied with our modification.
Commented [A16]: Awkward wording, not sure if “therefore” or “and K-deficient…” goes together, can you re-word this sentence?
Response: We appreciate you pointing out the critical question. The sentence was confused, and after the revision, this part are more logical: “It has been reported that sugars accumulation in leaf contributed to the replacement of osmotic molecules, however, inhibition of photosynthesis products transportation from leaf to root hindered root growth of plants [37]. In this study, the severe assimilation of polysaccharides in leaf and less carbohydrates transportation from leaf of genotype 122 might be related to its poor adaptation ability to low K.”.
