Plant Photosynthesis and Dry Matter Accumulation Response of Sweet Pepper to Water–Nitrogen Coupling in Cold and Arid Environment
Round 1
Reviewer 1 Report
A lot of basic information is given a lot of space, such that the obvious facts that water and nitrogen are important for production. When it finally comes to the interaction of the two, there seem to be some references missing (L 106-112).
Materials and methods:
Table 1 and figure 3: difficult to understand, please make clearer.
Some explanation could be given why all these parameters are measured. Is it known that they are correlated?
Equations: Why were these equations chosen? Do they tell something? Explain, please.
Statistical analysis: It seems like2-way anova with interaction terms was not used in this case, as would be normal with this experimental design. Is there a good reason for this?
How were significant differences determined when there are many results (e.g. fig 4-7).
Results:
Far too many results listed in the text, making it impossible to follow. Consider putting results e.g. about significant differences in tables, and only comment on important results in the text.
Fig 4-7: Difficult to see what the figures really tell us. Can it be shown in a different way, maybe showing unimportant results only as tables, and make figures that show something.
Fig 8: Give more explanation in the caption about the different types of curves.
Table 2-4: Give more explanation, what is this? What are the units?
Correlations: How surprising is this? Isn’t it generally known that these parameters are correlated? Isn’t it rather a question if it was worthwhile to measure all of them?
Discussion:
It starts well, by stating the most important results. But then it becomes confused, and states obvious truths such as that water ad nitrogen matters. It is also not necessary to repeat exact results here, and it just makes it harder to get the point.
There is also a lengthy discussion about what the mechanism behind apparent advantage of some deficit can be. It is questionable if this should be here, as only own results should be discussed. Could e.g. the models help explain mechanisms instead?
Results on correlation and models are not discussed?
Conclusion:
Should only state the important results.
English is mostly OK, but try to use simple language.
Author Response
Dear Reviewers:
Thank you for your comments concerning our manuscript entitled “Plant Photosynthesis and Dry Matter Accumulation Response of Sweet Pepper to Water-nitrogen Coupling in An Cold and Arid Environment” (Manuscript ID: water-2427563). The comments were all valuable and helpful in revising and improving our manuscript, in addition to contextualizing the significance of our research. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Revised components of the manuscript are indicated by the " Track Changes" function within the uploaded revised file.
Responses to Reviewer 1 Comments
Comment 1: A lot of basic information is given a lot of space, such that the obvious facts that water and nitrogen are important for production. When it finally comes to the interaction of the two, there seem to be some references missing (L 106-112).
Response 1: Thank you for pointing out this problem in manuscript. To improve the manuscript's rationality and completeness, we added references (Nos. [23] and [24]) and added content on the effects of water and nitrogen interactions on crops (please see lines 110-114).
Comment 2: Table 1 and figure 3: difficult to understand, please make clearer.
Response 2: We feel sorry for the inconvenience brought to the reviewer. In Table 1, The values at the ends of the horizontal lines indicate the upper and lower limits of the relative soil moisture content (Percent field capacity). Figure 3 shows the timing and volume of irrigation for each treatment at each growth stage of the pepper. See lines 190-191 and 194 for details of the modifications.
Comment 3: Some explanation could be given why all these parameters are measured. Is it known that they are correlated ?
Response 3: Thank you for this comment. It is well known that photosynthetic indicators and dry matter accumulation dynamics are closely related to crop yield. However, water and nitrogen coupling mechanisms on photosynthesis and dry matter accumulation in field sweet pepper are less studied (Wang et al., doi.org/10.1016/j.agwat.2021.107279). Therefore, there is necessary to reveal the regulatory effects of water and nitrogen coupling on yield by measuring photosynthesis and dry matter accumulation.
Comment 4: Equations: Why were these equations chosen ? Do they tell something ? Explain, please.
Response 4: We thank the reviewer for pointing out this issue. Logistic equations are well established as models for fitting crop growth processes. It fits the optimal equation by providing continuously measured indicators of the growth and development process. Growth key characteristic points and growth rates are obtained by calculation. This is important for determining the sweet pepper critical water and fertilization requirements periods, and precision irrigation and fertilization.
Comment 5: Statistical analysis: It seems like2-way anova with interaction terms was not used in this case, as would be normal with this experimental design. Is there a good reason for this ?
Response 5: We sincerely appreciate the valuable comments. We did a main effects analysis of the water-nitrogen interaction and supplemented item 2.4 with Duncan's multiple comparison method and significance levels (e.g. Table 3 and 4). Our data analysis is based on references [1] & [2].
[1] Wang, H.; Xiang, Y.; Zhang, F.; Tang, Z.; Guo, J.; Zhang, X.; Hou, X.; Wang, H.; Cheng, M.; Li, Z. Responses of yield, quality and water-nitrogen use efficiency of greenhouse sweet pepper to different drip fertigation regimes in northwest china. Agric. Water Manag. 2022, 260, 107279. doi.org/10.1016/j.agwat.2021.107279
[2] Xiang, Y.; Zou, H.; Zhang, F.; Wu, Y.; Yan, S.; Zhang, X.; Tian, J.; Qiang, S.; Wang, H.; Zhou, H. Optimization of controlled water and nitrogen fertigation on greenhouse culture of capsicum annuum. Sci. World J. 2018, 11. doi.org/10.1155/2018/9207181
Comment 6: How were significant differences determined when there are many results (e.g. fig 4-7).
Response 6: Thank for your comments. In Figures 4-7, we have used each growing season as a group, thus analyzing only the significance of differences between treatments at each growing season (one-way ANOVA test using SPSS 25.0 software).
Comment 7: Results: Far too many results listed in the text, making it impossible to follow. Consider putting results e.g. about significant differences in tables, and only comment on important results in the text.
Response 7: We gratefully appreciate for your valuable comment. We have carefully checked and refined this part of the result, and the changes are detailed in blue in the manuscript. The significance of each between-treatment will be shown in the figure for ease of reading.
Comment 8: Fig 4-7: Difficult to see what the figures really tell us. Can it be shown in a different way, maybe showing unimportant results only as tables, and make figures that show something.
Response 8: Thank you for the above suggestions. The data in Figures 4-7 are extensive and critical indicators. Presenting Figures in a table would increase the length and create reading difficulties across pages. A graphical representation more clearly conveys the trends in the indicators for each treatment at different growing seasons.
Comment 9: Fig 8: Give more explanation in the caption about the different types of curves.
Response 9: Thank you for your careful review. We have differentiated the dry matter accumulation curves and the dry matter accumulation rate curves with different colors. (please see lines 371-372)
Comment 10: Table 2-4: Give more explanation, what is this? What are the units ?
Response 10: Thank you for this comment. We have supplemented the relevant indicator units in Tables 2-4 (please see lines 385, 445-446, and 497). In Table 4, WUE, IWUE, and NPFP denote water use efficiency, irrigation water use efficiency, and nitrogen partial factor productivity, respectively, as explained in item 2.3.4.
Comment 11: Correlations: How surprising is this ? Isn’t it generally known that these parameters are correlated ? Isn’t it rather a question if it was worthwhile to measure all of them ?
Response 11: Thank for your comments. In this study, the linear equation between yield and net photosynthetic rate and dry matter accumulation could be constructed by excluding non-essential indicators after correlation analysis of each indicator.
Comment 12: Discussion: It starts well, by stating the most important results. But then it becomes confused, and states obvious truths such as that water ad nitrogen matters. It is also not necessary to repeat exact results here, and it just makes it harder to get the point.
Response 12: Considering the Reviewer’s suggestion, we have modified the order of some statements and trimmed down the exact results of repetitiveness (please see lines 542-545; Lines 580-582 were deleted).
Comment 13: There is also a lengthy discussion about what the mechanism behind apparent advantage of some deficit can be. It is questionable if this should be here, as only own results should be discussed. Could e.g. the models help explain mechanisms instead ?
Response 13: We sincerely appreciate the valuable comments. We have already discussed the mechanisms of water and nitrogen deficit in the Discussion section to the results of this study (please see lines 545-546, 550-558, 584-587, and 594-599).
Comment 14: Results on correlation and models are not discussed ?
Response 14: Thank you for pointing this out. We discuss the main results throughout the text, with the correlation analysis and logistic equations used as a tool only.
Comment 15: Conclusion: should only state the important results.
Response 15: We sincerely appreciate the valuable comments. We have modified the Conclusions section and made deletions to the non-main conclusions (please see lines 610-612 and 624-625).
Comment 16: English is mostly OK, but try to use simple language.
Response 16: Thank for your comments. The entire text has been carefully checked to avoid using long sentences wherever possible (please see lines 19-22, 42, 54, and 542-544).
Author Response File: 
Author Response.docx
Reviewer 2 Report
Presented paper is cohesive and well-put.
A couple of suggestions:
1. In some places abstract is too wordly and contains too much specific data. Try to condence and highlight the overall results.
2. Captions of the figures with lowercase letters should specify between which groups of measurements they demonstrate differences. Intuitively I wanted to compare letters between neighboring columns.
Mostly language is ok, but some sentences are hard to understand, e.g. lines 23-32, 53-56.
What do you mean by "soil capacity" on the line 134?
Author Response
Dear Reviewers:
Thank you for your comments concerning our manuscript entitled “Plant Photosynthesis and Dry Matter Accumulation Response of Sweet Pepper to Water-nitrogen Coupling in An Cold and Arid Environment” (Manuscript ID: water-2427563). The comments were all valuable and helpful in revising and improving our manuscript, in addition to contextualizing the significance of our research. The reviewer comments are laid out below in italicized font and specific concerns have been numbered. Revised components of the manuscript are indicated by the " Track Changes" function within the uploaded revised file.
Responses to Reviewer 2 Comments
Comment 1: Presented paper is cohesive and well-put.
Response 1: We thank the reviewer for reading our paper carefully and giving the above positive comments.
Comment 2: In some places abstract is too wordly and contains too much specific data. Try to condence and highlight the overall results.
Response 2: We thank the reviewer for pointing out this issue. We have condensed and highlighted the Abstract section as much as possible (please see lines 19-22, 26-28, 35,and 42).
Comment 3: Captions of the figures with lowercase letters should specify between which groups of measurements they demonstrate differences. Intuitively I wanted to compare letters between neighboring columns.
Response 3: Thank for your comments. Different lowercase letters within a column indicate a significant difference among treatments at p < 0.05. We have illustrated this in Table 2 and Figure 4 (please see lines 274-275 and 386).
Comment 4: Mostly language is ok, but some sentences are hard to understand, e.g. lines 23-32, 53-56.
Response 4: We thank the reviewer for pointing out this issue. We have adapted the sentence structure of this section to make it easier for the reader to understand (please see lines 26-28 and 54).
Comment 5:What do you mean by "soil capacity" on the line 134?
Response 5: We are very sorry for our carelessness. We have modified "soil capacity" with "soil bulk density"(please see lines 140).
Author Response File: Author Response.docx
