Optimizing Water and Nitrogen Management for Green Pepper (Capsicum annuum L.) under Drip Irrigation in Sub-Tropical Monsoon Climate Regions

Round 1

Reviewer 1 Report (New Reviewer)

This is very nice research. It deals with a topic of today since it presents the determination of the amount of water and N so that a crop reaches maximum yield and thereby make efficient use of water and nitrogen, a well-known problem in which it is wasted water and nitrogen generating possible environmental contamination.

However, there are a couple of concerns with the performance formulation and with the study itself in general. It is not clear why the authors generate two performance equations, one for 2019 and one for 2020, and perform the analyzes separating both years? When running a regression it is necessary to use all the data from both years and determine whether there are differences between years and between treatments. Since if there are differences in performance between one year and another, the data is encompassing the different effects that were not taken into account in the experiment.

On the other hand, the authors do not mention how they determined the regression and if the chosen one is the best. This equation is the most relevant in this work Y=f(I, Napp). It is almost certain that in a graph of Y, I and Napp the different ranges of water and Napp can be determined to obtain the highest production of the plant.

Minor concerns

The paragraph on lines 98-100 should be in Table 2.

What do the colors in Fig. 1 mean? What is DEM?

 

Table 1, line 111: says SWC should say Soil water content (SWC, %QFC) and urea (g plant-1) and delete what is in the table. What does the slash (/) in table 1 mean?

Table 2, Please include what do the capital letters represent? and what about the 19.32 kg of soil? Que cantidades y con que frecuencia fue aplicado el riego y el N?

When and how were the plants irrigated? How much water was irrigated each time?

 Lines 144-145: For this reason, it is important to know how much water was given in each irrigation period.

 Line 155: Explanation how the equations in table 4 were obtained is missing.

This table 3 is redundant since all data and significance are given in figs 2, 3 and 4. What about the interaction SWC and N? It needs the average values.

Line 180: Are these values  different?

Fig. 2: I still don't understand why you separated the years in the statistical analysis?

It is recommended to use all the data including the two years.

As well as determining if there are differences in the yield in the two years.

Fig. 3. Why does the name of the ordinate axis include a slash? The name must be: WUE (g L-1)

Fig. 4. Same than fig. 3.

The word rate is used to refer to the applied N, but they are not rates since it is not explained how often N is added.

Line 277: This seems to come out from the sleeve of the shirt because it appears without being reported in the methodological section. Although the analysis may contain good information regarding the maximum harvest, I do not think it adds better information than the one already given with the statistical relations of Y =f(I, Napp).

Why not make a similar graph based on the equations of harvest and the water and nitrogen required.

It is necessary to rethink tables 4, 5 and 6. There is redundant information

 

Line 347: it says g plant-r, it should say g plant-1 and a few others out there

Some aspects of taking the experiment to the field are not discussed.

 

Author Response

Responses to Reviewer

1.When running a regression it is necessary to use all the data from both years and determine whether there are differences between years and between treatments. Since if there are differences in performance between one year and another, the data is encompassing the different effects that were not taken into account in the experiment. On the other hand, the authors do not mention how they determined the regression and if the chosen one is the best. This equation is the most relevant in this work Y=f(I, N_app). It is almost certain that in a graph of Y, I and N_app the different ranges of water and N_app can be determined to obtain the highest production of the plant.

• Response:

We agree. This is a very good question. In this experiment, except for the amount of irrigation and nitrogen application (N_app) rate, other factors are consistent, so it is considered that other factors have no impact on the results of this experiment. In addition, the fitting results between the amount of irrigation and N_app rate and the yield, WUE and NUE are good in two years, so it can be considered that other factors not considered have no significant impact on the results of this experiment.

In this paper, through two years of field data research, the yield, WUE and NUE of green pepper all showed a parabola change relationship with the amount of irrigation and N_app rate. With reference to a large number of relevant references, this paper took the yield, WUE and NUE of green pepper as dependent variables, and the amount of irrigation and N_app rate as independent variables, and used MATLAB R2021a software to fit the relationship between them, and analyzed the precision of the fitting equation. The results met the requirements, so the fitting results were considered reasonable. In addition, the maximum values of the fitting equations were obtained within the value range of the irrigation mount and N_app rate. When the value range is outside, the yield, WUE and NUE tended to decrease. Therefore, it was considered that the maximum value obtained by the fitting equationcwas reasonable.

2. The paragraph on lines 98-100 should be in Table 2.

• Response: We agree and it has been revised.

3. What do the colors in Fig. 1 mean? What is DEM?

• Response:

Different color means different elevations, and DEM is the abbreviation of digital elevation model.

4. Table 1, line 111: says SWC should say Soil water content (SWC, %QFC) and urea (g plant-1) and delete what is in the table. What does the slash (/) in table 1 mean?

• Response: We agree and it has been revised.

5. Table 2, Please include what do the capital letters represent? and what about the 19.32 kg of soil? Que cantidades y con que frecuencia fue aplicado el riego y el N?

• Response:

The full name of abbreviations in Table 2 has been added to this papper. According to the measured volume of the pot, the soil shall be loaded with the weight of 19.32kg according to the bulk density of designed 1.3 g cm^-3.

The soil water content (SWC) was measured by weighing method once every three days. When the SWC was lower than the lower limit of the corresponding treatment, it was the time to irrigate, and the irrigation amount was 15%θFC(%θ field capacity simplified as %θFC). On the 5th day after transplanting, 6.0 g plant⁻¹ KH₂PO₅ and 30% of each treated N fertilizer were evenly mixed as a base fertilizer and applied as a fertilizer solution with irrigation water, and the remaining 70% N fertilizer was applied twice in the form of fertilizer solution during the flowering and fruit setting stage and the full fruit stage.

6. When and how were the plants irrigated? How much water was irrigated each time?

• Response：

When the soil water content (SWC) was lower than the corresponding lower limit of water level, it was the time to irrigate, and a single drip irrigation device was be used for drip irrigation, and the irrigation amount was 15%θFC (%θ field capacity simplified as %θFC). Because the data of single irrigation was not used in this paper. Therefore, the data of single irrigation amount was not reflected in this paper.

7. Lines 144-145: For this reason, it is important to know how much water was given in each irrigation period.

• Response：In this test, the total irrigation volume was equal to ET.

8. Line 155: Explanation how the equations in table 4 were obtained is missing.

• Response：

With irrigation amount and N_app rate as independent variables, and yield, WUE and NUE as dependent variables respectively, all formulas in Table 5 can be obtained by fitting the measured data with MATLAB R2021a software.

9.This table 3 is redundant since all data and significance are given in figs 2, 3

• Response：

Table 3 mainly reflects the impact of water, nitrogen and the interaction of water and nitrogen on ET, yield, WUE and NUE, while Figure 2 and Figure 3 mainly reflect the differences between treatments.

 

Reviewer 2 Report (New Reviewer)

see the attached file

Comments for author File: Comments.pdf

Author Response

1. Abstract：

The abstract is general and not informative. The abstract needs modification. Moreover, the authors should focus on what was the problem, the hypothesis, the treatments, main results and conclusion. All abbreviations should be first identified before use them even if they were in abstract or another part of the manuscript.

• Response:

Thank you very much for the positive comments and we agree. The abstract has been major revised to make the problem, the hypothesis, the treatments, the main results and the conclusion more clearer, and the article more readable. And In the full paper, all abbreviations have been rechecked.

2. Keywords: list the keywords in alphabetical order.

• Response: We agree and it has been revised.

3. Introduction:

No need of wolfberry introduction. Significant re-write of the introduction in needed. Furthermore, the objective of the current study was not stated clearly.

Please re-write the sentence in line 65~66(And 65 when water is in short supply....)

• Response:

Thank you very much for the comments and we agree. The team has referred to more relevant literature and has re-written the introduction.

4. Martials and methods

The complete analysis of soil analysis must be provided

• Response: We agree and it has been added. (Table 1)

5. Results and discussion:

And effort should be made to communicate the main results effectively and make reading more fluent.

• Response: We agree and it has been revised.

The discussion is too short.

• Response: We agree and it has been revised.

Please, remember that tables and figures must be selt-explanatory. That is, statistics and abbreviations used must be clearly explained. All table and figures must present standard error and suitable statistical analysis when appropriate.

• Response: We agree. In the full paper, all abbreviations have been re-checked.

6. More recent publications should be added to your discussion related to your work such as~.

• Response:

The team has referred to more recent references related to our work and made major modifications to the introduction, discussion and other parts.

 

Round 2

Reviewer 1 Report (New Reviewer)

In the first review of this manuscript, emphasis was placed on the regressions obtained for 2019 and 2020.

Authors say:

We agree. This is a very good question. In this experiment, except for the amount of irrigation and nitrogen application (Napp) rate, other factors are consistent, so it is considered that other factors have no impact on the results of this experiment. In addition, the fitting results between the amount of irrigation and Napp rate and the yield, WUE and NUE are good in two years, so it can be considered that other factors not considered have no significant impact on the results of this experiment.

This explanation does not solve the raised problem.

You say: …so it is considered that other factors have no impact on the results of this experiment.

Please prove it mathematically or statistically speaking, not in conjectures

Other factors are consistent, you say. How consistent, if there is not any further data included? How do you know other factors are consistent. Of course there are other factors that affect yield. I do not agree to use two equations in order to estimate yield in function of I and Napp.

Unfortunately, the authors did NOT consider the recommendations regarding the yield estimation model as a function of I and Npp. It is necessary that the data corresponding to the years 2019 and 2020 be used in just one general formulation. The authors seem to be ignorant of the year-over-year effects that this may have on yield (there seems to be a temporal interaction). In other words, the statistical analysis is poorly performed both in the analysis of variance and in obtaining yield estimates, wue and nue.

If the two equations 2019 and 2020 are analyzed, they turn out to be different. If everything were consistent the equation for 2019 must be equals to equation 2020, and it is not, all the coefficients are different, including the constant. How significant are each coefficient? The constants are significant? The fact that the estimates have a high p and R² does not mean that each factor chosen (I, Napp) is significant. Similar analysis for WUE and NUE. It is necessary to carry out a more detailed statistical analysis in this regard.

The fact that the best WUE and NUE cannot be achieved is not due to the lack of performing a finer experiment. However, as suggested in the first review it is necessary to plot the yield against I and Napp including the two years and choose the best yield with the minimum of water and N, it seems that this recommendation was not considered.

On the other hand, the authors clarify how they obtained these estimates, however, in the Materials and methods section there is nothing about it. The authors say that they carried out an analysis with the MATLAB R2021 program, but they will not explain more. Do we all Agronomy readers know about MatLab? Of course not, but statistics yes, so the authors should be more explanatory about it.

The manuscript continues to have many typographical errors. Please review all figures and tables.

Author Response

Authors say:

We agree. This is a very good question. In this experiment, except for the amount of irrigation and nitrogen application (N_app) rate, other factors are consistent, so it is considered that other factors have no impact on the results of this experiment. In addition, the fitting results between the amount of irrigation and Napp rate and the yield, WUE and NUE are good in two years, so it can be considered that other factors not considered have no significant impact on the results of this experiment.

This explanation does not solve the raised problem.

You say: …so it is considered that other factors have no impact on the results of this experiment. Please prove it mathematically or statistically speaking, not in conjectures. Other factors are consistent, you say. How consistent, if there is not any further data included? How do you know other factors are consistent.

• Response: This paper mainly studies the two factors of water and nitrogen, and other factors may also have impact. But during the experiment, we tried to keep other factors consistent. For the two-year experiment, the green pepper types were the same. Green peppers were all transplanted on May 1 and off-test on September 30. The experiment soil in two years was all taken from 0~40 cm of the same field. During the experiment, the measures such as rain shading and pest control were all the same. In addition, when the temperature out of the green greenhouse was higher than 30 ° in two years, both sides of the greenhouse would be opened for ventilation. Therefore, during the experiment, we could only try to keep other factors consistent during the experiment.

The corresponding part in the article had also been modified.

Of course there are other factors that affect yield. I do not agree to use two equations in order to estimate yield in function of I and N_app.Unfortunately, the authors did NOT consider the recommendations regarding the yield estimation model as a function of I and N_pp. It is necessary that the data corresponding to the years 2019 and 2020 be used in just one general formulation. The authors seem to be ignorant of the year-over-year effects that this may have on yield (there seems to be a temporal interaction). In other words, the statistical analysis is poorly performed both in the analysis of variance and in obtaining yield estimates, wue and nue. If the two equations 2019 and 2020 are analyzed, they turn out to be different. If everything were consistent the equation for 2019 must be equals to equation 2020, and it is not, all the coefficients are different, including the constant. How significant are each coefficient? The constants are significant? The fact that the estimates have a high p and R² does not mean that each factor chosen (I, Napp) is significant. Similar analysis for WUE and NUE. It is necessary to carry out a more detailed statistical analysis in this regard.

• Response: Thank you for your comments. After discussion by our team, our previous understanding was wrong, and your opinion was correct. Therefore, the corresponding part in the article had been revised. The general formulas had been established based on data of two years 2019 and 2020.

 

   The fact that the best WUE and NUE cannot be achieved is not due to the lack of performing a finer experiment. However, as suggested in the first review it is necessary to plot the yield against I and Napp including the two years and choose the best yield with the minimum of water and N, it seems that this recommendation was not considered.

• Response: Yes, we agree. The relationship models of yield, WUE, NUE and irrigation amount and N_app rate were proposed, respectively (Figure 5). According to Figure 5, the corresponding irrigation amount and N_app rate for yiled，WUE and NUE which could get a higher values were proposed.

On the other hand, the authors clarify how they obtained these estimates, however, in the Materials and methods section there is nothing about it. The authors say that they carried out an analysis with the MATLAB R2021 program, but they will not explain more. Do we all Agronomy readers know about MatLab? Of course not, but statistics yes, so the authors should be more explanatory about it.

• Response: Yes, we agree. The introduction of MATLAB R2021a was been added. The equations was established using the cftool in MATLAB R2021a, which is a commercial mathematics software produced by MathWorks of the United States and can be used in data analysis, image processing and other fields.

The manuscript continues to have many typographical errors. Please review all figures and tables.

• Response: All the tables and figures had been rechecked.

Reviewer 2 Report (New Reviewer)

Dear Editor Journal of Agronomy

Manuscript ID: Agronomy- -2009361

I re-reviewed the manuscript (Optimizing water and nitrogen management for green pepper (Capsicum annuum L.) under drip irrigation in sub-tropical monsoon climate regions) again and the authors made all the amendments that I asked before so I think the manuscript is suitable for publishing

Regards

 

Author Response

Thank you for your efforts in revising and publishing this article！

Round 3

Reviewer 1 Report (New Reviewer)

I have reviewed the new version (3) of the manuscript agronomy-2009361 in which changes appear to have been made in accordance to my comments, but I cannot see any. This version 3 of the manuscript contains the same
problems as version 1 and 2, or I probably can't find the latest version
where my comments and suggestions are considered. For example: I made
 the following comment:

Comment

Of course there are other factors that affect yield. I do not agree to
use two equations in order to estimate yield in function of I and N_app. Unfortunately, the authors did NOT consider the recommendations regarding the yield estimation model as a function of I and N_pp . It is necessary that the data corresponding to the years 2019 and 2020 be used in just one general formulation. The authors seem to be ignorant of the year-over-year effects that this may have on yield (there seems to be a temporal interaction). In other words, the statistical analysis is poorly performed both in the analysis of variance and in obtaining yield estimates, wue and nue. If the two equations 2019 and 2020 are analyzed, they turn out to be different. If everything were consistent the equation for 2019 must be equals to equation 2020, and it is not, all the coefficients are different, including the constant. How significant are each coefficient? The constants are significant? The fact that the estimates have a high/ p/ and R^2  does not mean that each factor chosen (I, Napp) is significant. Similar analysis for WUE and NUE. It is necessary to carry out a more detailed statistical analysis in this regard.

And authors answered:

Response:

Thank you for your comments. After discussion by our team, our previous understanding was wrong, and your opinion was correct. Therefore, the corresponding part in the article had been revised. The general formulas had been established based on data of two years 2019 and 2020.  And so on, in other comments. The authors are obstinate in presenting the two years analyzed separately, in addition to generating two equations, one for each year, and by doing so they are simply making a serious mistake since there is annual variability and it is not considered. However, an analysis like this is useless, because when wanting to determine what is the best proportion of water and nitrogen with the best yield, which model is used, 2019 or 2020? While if the model encompasses the two years there is no doubt. If the authors presented a general equation or model, it would have greater statistical strength, however they did NOT. I like this research a lot but from my point of view all the analyzes and results are very poorly treated, and this could be a serious flaw in the research.
If it is the correct version, that is, version 3, I do not recommend its
publication despite being a good topic.

There are more queries concerning the format of the manuscript, for
example, figure captions and table heads are not informative enough.

Author Response

Dear Reviewer 1,
    Thank you for all your efforts to improve the quality of this article. The team has carefully revised according to the comments.
    Different from fruit trees, cotton and other crops, green pepper is more sensitive to water and nitrogen, and it is uncertain which is more important. In addition, water and nitrogen require the same precision, and there is no subordination or primary secondary relationship between water and nitrogen, so the factorial design was adopted in this experiment. The factorial design was divided into two types: complete experiment and partial experiment. In this experiment, three levels of irrigation water and four levels of nitrogen fertilizer were set, with a total of 12 treatments, which belongs to the complete experiment in the factorial design and we re-described it in detail in MM sections.
    We randomly arranged the pots. This was because the factors that such as ventilation or sunlight were slightly different in different positions of the greenhouse, which may affect the experimental results. So the pots were arranged randomly and changed every week to eliminate the influence of these factors.
    The attachment includes the final version of this article (with change). I hope this revised version could meet the publication requirements of Agronomy journal.
    If you have any queries, please don’t hesitate to contact me.
Kind regards,
Xinyu Zhao
E-Mail: ruzaiyunduan001@163.com

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The purpose of this paper is to study the irrigation and nitrogen effects on the yields in red soil. However, this experiment was conducted in only one soil type, red soil, and one location in red soil region so further studies conducted in different soil type may be necessary in future. Thus, author should compare the results from the study with some previous studies conducted in other red soil regions or other soil types.

 

 

In line 47, please, provide full names of SWC and N

In method and materials

Please, describe how to sample the soils. There is no detail about soil sampling.

Ex) how many replicates of soil samples taken from size of field

In line 120,  please describe the θFC : water content at field capacity in text

In line 122, ‘According to investigation~~~ plant-1, please rewrite the sentence. Do not use according to, it does not make sense. Use in this experiment,

How did you calculate g/ plant? Fertilizer amount?

Figure 4, please describe detail about the figures. What does color and sized of circle indicates. And font size is too small to read.

 

In conclusion section, author should state future studies and some suggestions or considerations, not just stating findings.

Author Response

Responses to Reviewer

The purpose of this paper is to study the irrigation and nitrogen effects on the yields in red soil. However, this experiment was conducted in only one soil type, red soil, and one location in red soil region so further studies conducted in different soil type may be necessary in future. Thus, author should compare the results from the study with some previous studies conducted in other red soil regions or other soil types.

1. In line 47, please, provide full names of SWC and N

• Response: Thank you very much for the positive comments and we agree, and it has been provided.

2. In method and materials. Please, describe how to sample the soils. There is no detail about soil sampling. Ex) how many replicates of soil samples taken from size of field

• Response: Thank you very much for the positive comments and we agree. Three points were randomly selected within the soil sampling range in the field, the soil drilling method was used to take soil sample, and the soil samples were taken back to the laboratory to measure each index and obtain the average value of each inde.

3. In line 120,  please describe the θFC : water content at field capacity in text

• Response: We agree and it has been added.

4. In line 122, ‘According to investigation~~~ plant-1, please rewrite the sentence. Do not use according to, it does not make sense. Use in this experiment.

• Response: We agree and it has been revised.

5. How did you calculate g/ plant? Fertilizer amount?

      Response: Yes, in this paper, bucket planting was used. When fertilizing, the        fertilization amount of each green pepper was strictly measured. Therefore,           in this paper, the unit of fertilization per green pepper was g/plant

6. Figure 4, please describe detail about the figures. What does color and sized of circle indicates. And font size is too small to read.

• Response: Thank you very much for the comments and we agree. This figure was the isopleth map of C1, C2 and C3 based on the likelihood function. The colors in the figure represent the values of the C1, C2 and C3, and the sized of circle indicated the size of the C value.

7. In conclusion section, author should state future studies and some suggestions or considerations, not just stating findings.

• Response: This is a great constructive opinion which is important for our research. Thank you very much for the comments and it has been added.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript submitted for review concern very important issues of the reduction of water use and the level of nitrogen fertilization in plant production.

However, it cannot be published in its present form. Clear any doubts and make corrections.

Reviewer's comments below.

In ‘Abstract’  and ‘ Experimental design’ given two different information:

“Page 1 lines 20-21:  The main treatments comprised of four N levels (N1: 6.0, N2: 3.0, N3: 1.5 and N4: 0.0 g plant⁻¹), which were designated as high N, medium N, low N and no N, respectively.”

while

“According to investigation, the urea used by local farmers in green pepper planting was 6.0 g plant⁻¹. In this study, three N reduction treatments were added based on this, and four levels were set, which were high N (N1: 6.0), medium N (N2: 3.0), low N (N3: 1.5), and no N (N4: 0.0 g plant⁻¹).”

These assumptions apply to nitrogen fertilization (urea) or is it a nitrogen dose? This is not clearly stated. Throughout the work, the Authors alternately use fertilization with urea or nitrogen in the same doses. Corrections should be made in the text and it should be clearly stated what the levels N1, N2, N3, N4. Preference should be given to the application dosses in the form of the component (Nitrogen). What specific fertilizer has been applied (trade name), with what N content?

 

In:  Experimental site:

No information about content of P, K, Mg and Ca in the soil.

page 4, lines 133 - 134

“The air-dried soil was mixed with organic fertilizer (chicken manure, 2.19% N) at a ratio of 1:40, and mixed evenly.”

Is the proportion correct? - as many as 40 units of chicken manure! On one part of the soil? In this case, what is the point of conducting an experiment with nitrogen fertilization?

What variety of pepper was used in the research?

Explain why soil water content (SWC) were only controlled during the flowering, fruit set and full fruiting phases?

How many times has each combination been irrigated during the growth of the pepper?

page 5, lines 161-164

“m_plant indicates the plant weight (kg), referring to the plant of similar size in the nearby field, sampling and weighing at different growth stages using the destruction method which were 0.10, 0.30 and 0.60 kg in the green pepper seedling stage, flowering and fruit setting stage, and full fruit stage, respectively in this experiment.”

In my opinion, m_plant (equation 1) - it should be the weight of the plant grown in the same conditions as the others, and not plants "of similar size from a nearby field". How was it determined that the size was similar?

Please correct figures 3.

Barrel or buckets (lines 132-133 vs 158)

Author Response

Responses to Reviewer

The manuscript submitted for review concern very important issues of the reduction of water use and the level of nitrogen fertilization in plant production. However, it cannot be published in its present form. Clear any doubts and make corrections.

Reviewer's comments below.

1. In ‘Abstract’  and ‘ Experimental design’ given two different information:

“Page 1 lines 20-21:  The main treatments comprised of four N levels (N1: 6.0, N2: 3.0, N3: 1.5 and N4: 0.0 g plant−1), which were designated as high N, medium N, low N and no N, respectively.” while “According to investigation, the urea used by local farmers in green pepper planting was 6.0 g plant−1. In this study, three N reduction treatments were added based on this, and four levels were set, which were high N (N1: 6.0), medium N (N2: 3.0), low N (N3: 1.5), and no N (N4: 0.0 g plant−1).” These assumptions apply to nitrogen fertilization (urea) or is it a nitrogen dose? This is not clearly stated. Throughout the work, the Authors alternately use fertilization with urea or nitrogen in the same doses. Corrections should be made in the text and it should be clearly stated what the levels N1, N2, N3, N4. Preference should be given to the application dosses in the form of the component (Nitrogen). What specific fertilizer has been applied (trade name), with what N content?

• Response: Thank you very much for the comments and it has been added. The nitrogen fertilizer in this experiment was applied in the form of urea, and the nitrogen content was 46.2%. If pure nitrogen content was used in the paper, the accuracy of the data would be reduced, which was the reason why urea was used in this paper.

2. In:  Experimental site: No information about content of P, K, Mg and Ca in the soil.

• Response: Thank you very much for the comments and it has been added.

3.Page 4, lines 133 – 134. “The air-dried soil was mixed with organic fertilizer (chicken manure, 2.19% N) at a ratio of 1:40, and mixed evenly.” Is the proportion correct? - as many as 40 units of chicken manure! On one part of the soil? In this case, what is the point of conducting an experiment with nitrogen fertilization?

• Response: Thank you very much for the comments. it was wrong and has been revised.

4. What was used in the research?

• Response: The variety of green pepper in this experiment was "sweet pepper F1 hybrids"

5. Explain why soil water content (SWC) were only controlled during the flowering, fruit set and full fruiting phases?

• Response: In the seedling stage, the region of the red soil is in the rainy season, and the soil water content is also high, so the range of irrigation was uniform to %θFC at this stage, while in the late fruiting stage, the local farmers are no longer irrigated, so this experiment was not irrigated. Therefore, the SWC processing was only controlled during the flowering, fruit set and full fruiting phases.

6. How many times has each combination been irrigated during the growth of the pepper?

• Response: Table 1 shows the number of irrigation times for each treatment of green pepper in two years.

Table 1 The number of irrigation times of green pepper in two years.

Treatments	Irrigation times
	2019	2020
W1N1	42	43
W1N2	42	43
W1N3	41	43
W1N4	40	41
W2N1	36	36
W2N2	36	37
W2N3	36	35
W2N4	34	35
W3N1	33	34
W3N2	33	33
W3N3	32	33
W3N4	30	32

7. page 5, lines 161-164: “m/plant indicates the plant weight (kg), referring to the plant of similar size in the nearby field, sampling and weighing at different growth stages using the destruction method which were 0.10, 0.30 and 0.60 kg in the green pepper seedling stage, flowering and fruit setting stage, and full fruit stage, respectively in this experiment.” In my opinion, m/plant (equation 1) - it should be the weight of the plant grown in the same conditions as the others, and not plants "of similar size from a nearby field". How was it determined that the size was similar?

• Response: This is a great constructive opinion which is important for our research. Thank you very much for the comments and it has been added. In the experimental design, the team also conducted repeated research on this issue. On the basis of reviewing a large number of relevant literatures, it is believed that 100 green peppers were planted in the field next to the experimental area at the same time. Plants with basically the same height and crown width were selected for measurement, and the calculation results were more accurate.

8. Please correct figures 3.

• Response: We agree and it has been revised.

9. Barrel or buckets (lines 132-133 vs 158)

• Response: We agree and it has been revised.

Author Response File: Author Response.docx