Review Reports - Optimizing Center Pivot Irrigation to Regulate Field Microclimate and Wheat Physiology under Dry-Hot Wind Conditions in the North China Plain

Round 1

Reviewer 1 Report

This research paper has conducted a field experiment research to investigate the field microclimate , net photosynthetic rate, chlorophyll content of flag leaves, grain filling rate, and wheat yield after sprinkler misting under the condition of DHW climate. The research idea is good and is based on real world problem. This manuscript is written very well. However, I have few suggestions that may improve the quality of paper in the context of writing.

Authors have used the abbreviations in abstract. They may like to remove abbreviations in abstract and or write in full those abbreviations.
Authors have cited the articles with the name of the authors and the reference numbers. Please follow one pattern if you have mentioned the reference number of the article cited in the text, it is not necessary to add the names of the authors.
Section 2.3.1 where authors discussed the time period used the term 5s, use the proper name here.
When you are introducing LSD test name first time, add the full LSD test name then use its abbreviation LSD. On Page 12, authors use the term TGW, add its full name and explain it.
Please check the following references carefully (2, 4,9,11,16,21,23, and 29) as some references are missing page numbers.

Author Response

Dear Reviewer,

Thanks for your valuable comments concerning our manuscript entitled “Optimizing center pivot irrigation to regulate field microclimate and wheat physiology under dry-hot wind conditions in the North China Plain” (ID: water-1585683). Those comments are very helpful for improving our paper. Based on the comments, the original manuscript has been carefully corrected. In addition, some editorial changes of the paper also have been made to meet with the requirements of the journal. All of the corrections were marked in the revised manuscript. The following are the responses to the editor and reviewers’ comments:

Reviewer #1: (Manuscript ID: water-1585683)

General comments: This research paper has conducted a field experiment research to investigate the field microclimate, net photosynthetic rate, chlorophyll content of flag leaves, grain filling rate, and wheat yield after sprinkler misting under the condition of DHW climate. The research idea is good and is based on real world problem. This manuscript is written very well.

However, I have few suggestions that may improve the quality of paper in the context of writing.

Response: We all thank for your worthy comments.

Specific comments:

1. Authors have used the abbreviations in abstract. They may like to remove abbreviations in abstract and or write in full those abbreviations.

Response: Thank you for pointing this out. We apologize for this flaw in the original paper. According to valuable comments, we rewrote the full name of the abbreviations in the abstract in the revised manuscript.

2. Authors have cited the articles with the name of the authors and the reference numbers. Please follow one pattern if you have mentioned the reference number of the article cited in the text, it is not necessary to add the names of the authors.

Response: Thanks for your suggestions. According to the latest format requirements of Water journal, we preferred to the reference number of the article cited in the revised version.

3. Section 2.3.1 where authors discussed the time period used the term 5s, use the proper name here.

Response: Thank you for pointing this out. The full name of 5s is 5 seconds. In the revised version, we modified this term in Section 2.3.1.

4. When you are introducing LSD test name first time, add the full LSD test name then use its abbreviation LSD. On Page 12, authors use the term TGW, add its full name and explain it.

Response: We apologize for this flaw in the original paper. According to your valuable comments, we added the full name of LSD test in the revised manuscript. In addition, we also added the full writing of TGW.

5. Please check the following references carefully (2, 4, 9, 11, 16, 21, 23, and 29) as some references are missing page numbers.

Response: Thank you for pointing this out. We apologize for this flaw in the reference section. We carefully checked the mentioned references and added the page numbers in the revised paper.

Author Response File: Author Response.pdf

Reviewer 2 Report

Optimizing center pivot irrigation to regulate field microclimate and wheat physiology under dry-hot wind conditions in the North China Plain

I took this review because I appreciate the roll of irrigation and evaporation in changing the microclimate around plants. Certainly, this is of interest as we see the effects of global warming. After reading the manuscript I feel there is new information that will add to the literature, however I feel the manuscript needs modification and revision before publication.

The first thing that struck me, and each of the three times I read the manuscript, was the over use (in my opinion) of abbreviations. Constantly having to go back to find the meaning of non-standard abbreviations makes the reading of the manuscript very difficult. Abbreviations are to help the reader (for instance, in tables and figures due to size limitations), and of course some abbreviations are so standard that “everyone” understands them (e.g., K, NaOH, DNA, etc.), but in general abbreviations should be used judiciously. Even the third time I read the manuscript I keep having to go back to where the abbreviation was defined to see what it stood for. This is an Editorial issue (and the Editor can say what they feel), but a page of “abbreviations used in the paper” would help the reader significantly. Really, “CK” versus “control,” this is not standard (and just four more letters). CK is fine in tables and figures if defined in the title or in a footnote, but in the body of the manuscript too many abbreviations makes it difficult to read. Actually, “DHW’ takes away the emphasis and importance of the problem, rather just saying “dry-hot wind.” “Hot-dry wind” is descriptive and reminds the reader of the importance of the problem. W1 and W2 takes away the emphasis on irrigation, it is much easier to understand when you say “there is a difference when 5 mm, or 2.5 mm, of water is applied,” rather than W1 or W2. I kept having to remember, now is W1 more water or is it W2?

Now having just made a big deal about the use of abbreviations, I do have to say that the manuscript really does read generally well.

I will come back to the Abstract, but the Introduction states the problem, backs it up with appropriate literature citations, and leads nicely into the objectives of the study.

In the Materials and Methods, you state, lines 123-124, that irrigation is scheduled “based on soil water content,” but it does not say how soil water content is measured. In Figure 1, you need in the title to describe what is A and what is B. It would also be easy to replace, W1, W2, and CK with 5.0, 2.5, and 0.0 mm irrigation water. DHW needs to be defined (actually no need for the abbreviation, just write it out). A reader should be able to understand a figure or table without reading the manuscript. You need more on Figure 1. B., for instance what are those things at 5, 40, 80, and 200 cm, and what are they measuring?

In the Results and Discussion section:

Figure 2, you have bars for rainfall in 2018 and 2019, but it needs to be defined that they are for rainfall. You do a very nice job of defining all the symbols for relative humidity and air temperature, but not the symbols for rainfall.

In Figure 3, you need to designate in some way the days where dry-hot wind occurred each year. If someone read the manuscript they could see how you defined dry-hot wind, but if not, how do I know which days you are talking about. In Figures 4 and 5, you need to define, or better yet just write out, CK, W1, and W2, and the definitions of symbols should be at the beginning of the Figure, not the last box. When I read it at first, I had no idea what it was telling me. You did do a nice job in the body of the paper describing what was happening and what was different at each level measured.

Figure 6, again, CK, W1, and W2 need to be defined, or really just written out. You should show on the figure where you think the steady decline, rapid decline, and slow decline stages are on the figure. Perhaps with a line and explanation (in the title or figure) that steady decline is between, for example May 16 and May 30, 2018, etc. I am just guessing where each stage is on your figure. Also, where you show significance, what treatments are significantly different? This can be done in the title.

To me, there are all sorts of problems with Figure 7. First, of course, CK, W1, and W2 need to be defined, or write out Control (0.0 mm), 2.5 mm, and 5.0 mm of irrigation water applied. A SPAD is what you read off a machine (with the same name as the machine), but it is not a chlorophyll content measurement. You read relative SPAD meter values that are proportional to the amount of chlorophyll present in the leaf. In order to convert these values into absolute units of chlorophyll concentration (mg chlorophyll per litre of water), calibration curves must be derived and utilized. This needs explanation in the Materials and Methods, and the Results and Discussion. Again, you have dates with significant differences, but which treatments are different from each other?

In Figure 8, you need to define CK, W1, and W2, and the stages that are rapid rise, slow rise, rapid decline, and slow decline (as described above), and when there are significant differences, what is different. Now, I also have a problem in the body of the manuscript. In lines 313 to 318, you state that the control is significantly lower that the 2.5 mm and 5.0 mm treatments. You go on the say that the 2.5 mm and 5.0 mm treatments were not significantly different from each other. Fine, but then you go on to say that the rate of grain filling in the 5.0 mm treatment is 0.5 and 0.6 g/day higher than the 2.5 mm and 0.0 mm irrigation treatments. This is not true! If they are not significantly different, they are not different. Don’t make more of this than there is.

Table 1, Of course define CK, W1, and W2, or write out which would be preferred, and TGW. There are no differences in number of spikes and grains per spike. Again, lines 339-343, even though there are no significant differences, you are saying that grains per spike are higher in the 5.0 mm treatment, than the 2.5 mm, and 0.0 mm irrigation treatments. They are not higher! If there is no significant difference, they are not higher. The thousand grain weight is significantly different (5.0 mm and 2.5 mm higher than the 0.0mm) in 2018, and the yield is significantly different in 2018 (although you have a NS on the table, with the 5.0 mm greater than the 0.0 mm, but neither the 0.0 mm or the 5.0 mm are greater than the 2.5 mm treatment. Almost every thing you say between lines 346 and 354 needs to be rewritten because if they are not significantly different, you cannot say they are higher. Here is a chance for a nice discussion about how the two years are different: more severe dry-heat wind in 2018, more irrigation water applied in 2019, the number of dry-heat wind days in 2018 greater than in 2019, etc.

The Conclusion and Abstract need to be re-written to reflect what are significantly different. Also, in line 380, I do not understand what “variety” means in this sentence. You have some interesting findings at different heights around the plants. But most of what you found was similar to what others have reported. That is OK. But really, you only had dry-heat wind days four times in 2018 and three times in 2019. The years you measured did not seem to be extreme, or perhaps you should redefine dry-hot wind days. From what you found, was it worth the water and expense of running the sprinkler system? Perhaps irrigating between these times more days would give a larger difference in grain fill and yield.

Author Response

Reviewer #2: (Manuscript ID: water-1585683)

General comments: Optimizing center pivot irrigation to regulate field microclimate and wheat physiology under dry-hot wind conditions in the North China Plain.

Response: Thank for your worthy comments. This study provided an approach for proper regulation of field microclimate around plants through sprinkler irrigation. We are quite interested in the comprehensive use of sprinkler irrigation technology on field crops.

Specific comments:

1. The first thing that struck me, and each of the three times I read the manuscript, was the over use (in my opinion) of abbreviations. Constantly having to go back to find the meaning of non-standard abbreviations makes the reading of the manuscript very difficult. Abbreviations are to help the reader (for instance, in tables and figures due to size limitations), and of course some abbreviations are so standard that “everyone” understands them (e.g., K, NaOH, DNA, etc.), but in general abbreviations should be used judiciously. Even the third time I read the manuscript I keep having to go back to where the abbreviation was defined to see what it stood for. This is an Editorial issue (and the Editor can say what they feel), but a page of “abbreviations used in the paper” would help the reader significantly. Really, “CK” versus “control,” this is not standard (and just four more letters). CK is fine in tables and figures if defined in the title or in a footnote, but in the body of the manuscript too many abbreviations makes it difficult to read. Actually, “DHW’ takes away the emphasis and importance of the problem, rather just saying “dry-hot wind.” “Hot-dry wind” is descriptive and reminds the reader of the importance of the problem. W1 and W2 takes away the emphasis on irrigation, it is much easier to understand when you say “there is a difference when 5 mm, or 2.5 mm, of water is applied,” rather than W1 or W2. I kept having to remember, now is W1 more water or is it W2?

Now having just made a big deal about the use of abbreviations, I do have to say that the manuscript really does read generally well.

Response: Thanks for your suggestions. Indeed, the use of abbreviation is to make the paper easier to understand. According to your valuable comments, we have rewritten the full names of most abbreviations such as DHW, NCP, AT, RAH, WS, TGW, etc. At the same time, we kept the abbreviation of W1, W2 and CK after reading the latest published papers in Water journal, while adding the full names when they appeared in tables and figures.

2. I will come back to the Abstract, but the Introduction states the problem, backs it up with appropriate literature citations, and leads nicely into the objectives of the study.

Response: Thanks for your suggestion. We appreciate the encouraging comments.

3. In the Materials and Methods, you state, lines 123-124, that irrigation is scheduled “based on soil water content,” but it does not say how soil water content is measured. In Figure 1, you need in the title to describe what is A and what is B. It would also be easy to replace, W1, W2, and CK with 5.0, 2.5, and 0.0 mm irrigation water. DHW needs to be defined (actually no need for the abbreviation, just write it out). A reader should be able to understand a figure or table without reading the manuscript. You need more on Figure 1. B., for instance what are those things at 5, 40, 80, and 200 cm, and what are they measuring?

Response: We apologize for this flaw in the previous version of our manuscript. The soil water content measured by a gravimetric method and the changes has been found in Line 123-124. In Figure 1, we described A and B in the title and defined W1 and W2 with 2.5, 5 mm irrigation treatments respectively, and CK with no irrigation during dry-hot wind condition. The 5, 40, 80, and 200 cm are sensors’ heights at which temperature and humidity were measured as we mentioned in Lines 153-157.

4. In the Results and Discussion section: Figure 2, you have bars for rainfall in 2018 and 2019, but it needs to be defined that they are for rainfall. You do a very nice job of defining all the symbols for relative humidity and air temperature, but not the symbols for rainfall.

Response: We apologize for this flaw in the original manuscript. The definition of the rainfall symbols in Figure 2 has been supplemented.

5. In Figure 3, you need to designate in some way the days where dry-hot wind occurred each year. If someone read the manuscript they could see how you defined dry-hot wind, but if not, how do I know which days you are talking about. In Figures 4 and 5, you need to define, or better yet just write out, CK, W1, and W2, and the definitions of symbols should be at the beginning of the Figure, not the last box. When I read it at first, I had no idea what it was telling me. You did do a nice job in the body of the paper describing what was happening and what was different at each level measured.

Response: Thank for your valuable comments. We have explained the days when dry-hot wind occurred in 2018 and 2019 in Lines 198-200. In Figures 4 and 5, we have added the definitions of these symbols at the beginning of Figure in the revised manuscript. And we have defined all CK, W1 and W2 appeared in Figures and Table in the revised manuscript.

6. Figure 6, again, CK, W1, and W2 need to be defined, or really just written out. You should show on the Figure where you think the steady decline, rapid decline, and slow decline stages are on the Figure. Perhaps with a line and explanation (in the title or Figure) that steady decline is between, for example May 16 and May 30, 2018, etc. I am just guessing where each stage is on your Figure. Also, where you show significance, what treatments are significantly different? This can be done in the title.

Response: Thank you for pointing this out. We defined CK, W1, and W2 in Figure 6 in the revised manuscript. We added steady decline, rapid decline, and slow decline stages in Figure 6 in the revised manuscript. In the original version we used the symbol of * to indicate the significant differences among treatments, and we also defined it in the title.

7. To me, there are all sorts of problems with Figure 7. First, of course, CK, W1, and W2 need to be defined, or write out Control (0.0 mm), 2.5 mm, and 5.0 mm of irrigation water applied. A SPAD is what you read off a machine (with the same name as the machine), but it is not a chlorophyll content measurement. You read relative SPAD meter values that are proportional to the amount of chlorophyll present in the leaf. In order to convert these values into absolute units of chlorophyll concentration (mg chlorophyll per litre of water), calibration curves must be derived and utilized. This needs explanation in the Materials and Methods, and the Results and Discussion. Again, you have dates with significant differences, but which treatments are different from each other?

Response: Thank for your valuable comments. We have defined CK, W1, and W2 in Figure 7. SPAD-502 meter is a hand-held device widely used for the rapid, accurate and non-destructive measurement of leaf chlorophyll concentrations, which can measure relative SPAD meter values proportional to the amount of chlorophyll present in the leaf. The instrument measures transmission of red light at 650 nm, at which chlorophyll absorbs light, and transmission of infrared light at 940 nm, at which no absorption occurs. On the basis of these two transmission values, the instrument calculates a SPAD value that is well correlated with chlorophyll content. Thus, we used SPAD values to express the relative chlorophyll content of leaves in this study. We have made supplementary explanations in the Measurements section. We described the significant difference of the treatments in Lines 313-317.

The above-mentioned measurement device and calculation method can be found in the following papers:

[1] Zhang, Y,; Liu, L. Z,; Chen, X,; Li, J. C. Effects of Low-Temperature Stress during the Anther

Differentiation Period on Winter Wheat Photosynthetic Performance and Spike-Setting Characteristics. Plants. 2022, 11, 389. https://doi.org/10.3390/plants11030389.

[2] Künzel, A.; Münzel, S.; Böttcher, F.; Spengler, D. Analysis of Weather-Related Growth Differences in Winter Wheat in a Three-Year Field Trial in North-East Germany. Agronomy. 2021, 11, 1854. https:// doi.org/10.3390/agronomy11091854.

[3] Ling, Q.H,; Huang, W.H,; Jarvis, P. Use of a SPAD-502 meter to measure leaf chlorophyll

concentration in Arabidopsis thaliana. Photosynth Res. 2011, 107:209–214.

8. In Figure 8, you need to define CK, W1, and W2, and the stages that are rapid rise, slow rise, rapid decline, and slow decline (as described above), and when there are significant differences, what is different. Now, I also have a problem in the body of the manuscript. In lines 313 to 318, you state that the control is significantly lower that the 2.5 mm and 5.0 mm treatments. You go on the say that the 2.5 mm and 5.0 mm treatments were not significantly different from each other. Fine, but then you go on to say that the rate of grain filling in the 5.0 mm treatment is 0.5 and 0.6 g/day higher than the 2.5 mm and 0.0 mm irrigation treatments. This is not true! If they are not significantly different, they are not different. Don’t make more of this than there is.

Response: Thank you for pointing this out. We apologize for this flaw in the original manuscript. We have added rapid rise, slow rise, rapid decline, and slow decline stages in Figure 8 in the revised manuscript. Also, we defined CK, W1, and W2 and described the significant difference of the treatments in the Figure title. Furthermore, we have rewritten the corresponding sentences in Lines 337-343 in the revised manuscript.

9. Table 1, of course define CK, W1, and W2, or write out which would be preferred, and TGW. There are no differences in number of spikes and grains per spike. Again, lines 339-343, even though there are no significant differences, you are saying that grains per spike are higher in the 5.0 mm treatment, than the 2.5 mm, and 0.0 mm irrigation treatments. They are not higher! If there is no significant difference, they are not higher. The thousand grain weight is significantly different (5.0 mm and 2.5 mm higher than the 0.0 mm) in 2018, and the yield is significantly different in 2018 (although you have a NS on the table, with the 5.0 mm greater than the 0.0 mm, but neither the 0.0 mm or the 5.0 mm are greater than the 2.5 mm treatment. Almost every thing you say between lines 346 and 354 needs to be rewritten because if they are not significantly different, you cannot say they are higher. Here is a chance for a nice discussion about how the two years are different: more severe dry-heat wind in 2018, more irrigation water applied in 2019, the number of dry-heat wind days in 2018 greater than in 2019, etc.

Response: Thank for your valuable comments. We apologize for this flaw in the previous manuscript. We have defined CK, W1, W2 in the updated version of the manuscript. In the presentation of the study results, we firstly compared whether there was a significant difference among the three treatments based on the results of the variance test at a probability level of P=0.05, and then compared the average value based on the specific values corresponding to different treatments. We believe that these two are not contradictory. In order to make it more clearly, we have rewritten this section in Lines 360-381 in the revised manuscript.

10. The Conclusion and Abstract need to be rewritten to reflect what are significantly different. Also, in line 380, I do not understand what “variety” means in this sentence. You have some interesting findings at different heights around the plants. But most of what you found was similar to what others have reported. That is OK. But really, you only had dry-heat wind days four times in 2018 and three times in 2019. The years you measured did not seem to be extreme, or perhaps you should redefine dry-hot wind days. From what you found, was it worth the water and expense of running the sprinkler system? Perhaps irrigating between these times more days would give a larger difference in grain fill and yield.

Response: Thank for your valuable comments. We apologize for this flaw in the original manuscript. We have rewritten the parts of the Conclusion and Abstract according to your valuable comments. In the original manuscript, we wanted to use "variety" to express the changes in field microclimate after irrigation regulation which can be found in Lines 405-408 in the revised manuscript. Indeed, as you said, most of the dry-hot winds belonged to light grades during the wheat grain filling period in 2018 and 2019. Perhaps in years with a high frequency of moderate and severe grades of dry-hot winds, the effect of irrigation regulation to improve yield will be more significant. For the definition of dry-hot wind, we follow the industry standard for the classification of disaster grade of dry-hot wind for wheat. Due to the high frequency of dry-hot wind during the filling period of winter wheat in the North China Plain, we believe that a small amount of irrigation regulation is a more effective and practical means to avoid wheat yield reduction, especially with the use of high automated irrigation systems like center pivot irrigation system.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I commend the authors on the revision of this manuscript. It is much easier to read and will add to the literature in this area. It is now much easier to see the significance of the work.