Quantitative Analysis of Source-Sink Relationships in Two Potato Varieties under Different Nitrogen Application Rates
Round 1
Reviewer 1 Report
1. The English language needs proofreading.
2. Please consider modifying the title as ‘Quantitative Analysis of Source-Sink Relationships of Two Potato Varieties under Different Nitrogen Application Rates’.
3. Lines 20-21: the sentence needs rephrasing.
4. The Abstract was too long. Please consider refining it, especially the last sentence.
5. Lines 68-69: Please cite the lasted data if possible.
6. Lines 98-99: This sentence needs more explanation.
7. Table 2: Please explain W and R in the table.
8. Figure 4: Why there was sharp increase in source activity around 6/19?
9. Lines 500-501: Is this conclusion from your study or from previous study? If it was from your study, it may be unreasonable since you only have two application rates.
10. Lines 506-507: How did you obtain this conclusion?
11. The limitations and future studies should be mentioned in the conclusion section.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The Abstract requires significant modifications; it is too long, too detailed, unfocused, and lacks any discrimination between Results and Conclusions. There is no concise and clear story, as expected from an Abstract.
Some editing work is required to shorten and focus the text throughout. For instance, in lines 77-79, and elsewhere.
The description of N application is too dull; which type of urea was applied? was it granular? was the fertilizer embedded into the soil? These questions are in concern with the duration of N availability after application. Urea is widely used as it is inexpensive. However, under the high daily temperatures during the growing season (day temperature above 20C up to 32C, Fig. 1), with fluctuating soil moisture under frequent rainy days (irrigation is not mentioned in the paper), and a significantly alkaline soil (Table 1), N availability is expected to rapidly decline within 10-20 days. If 2/3 of the seasonal N was applied pasally and the rest upon hilling, the potato crop had a very low chance to use most of the fertilizer applied. Naturally, zero N application had the lowest yield, while N150 was remarkedly higher. However, the marginal yield increase from N150 to N300 was much smaller, not reflecting the 100% increase in N application, at all. This fact highlights the basic poor N use eficiency in the experiment, due to wrong N application practices. This point is strongly demonstrated by the very low N uptake efficiency throughout the experiment - less than 5% (Table 3), and the decline in NUE when N application rates were increased from 150 to 300 kg/ha.
The different performance between the two cultivars might partly arise from some differences in NUE, but also, and even greater, from other intrinsic, genetic differences.
Fig. 3: when comparing treatments or cultivars, Y axis must be uniform, at least in the same year. The way displayed here is very difficult to see differences. Please, improve accordingly.
The parameter analyses, starting in Chapter 3.3. until the discussion, is very interesting but too detailed, difficult to read and follow. Furthermore, I assume that upon improved N application practices, as suggested below, large parts of the picture displayed might significantly change.
This comprehensive study is impressive by the bgreat work done trying to elucidate relevant modeling parameters in order to distinguish between cultivars and their NUE. The principal approach of the authors is right; cultivars with higher NUE should be preferred in order to reduce the concequences of excess fertilization rates. Nevertheless, the seasonal N application rate should not be the sole parameter involved in evaluating crops' N balance. To my opinion, fitting N application during the season in full accordance with prompt crop requirements would be a more effective approach. Thus, the seasonal N rate should focus on supporting the vegetative growth phase and be divided to several applications during this period. During tuber growth, N application must be stopped in order to avoid competition by the vegetative growth. The division is required to overcome the problem of urea losses to the atmosphere and ground under the local conditions. The type of N fertilizer may also be changed, but this is a question of cost. In this approach, determining the seasonal rate should be done by testing stepwise increases from a basic level of 100 up to 300 kg/ha. I believe that 150 kg/ha would be found sufficient.
As a bottom line, unfortunately, the present study has failed to include some vital parameters in the scope of potato N balance, particularly the status of N availability in the root profile during the season. Therefore, and in spite of my deep appreciation of the huge work done here, I suggest not to publish.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments on Manuscript Agronomy-2310997
The study tried to propose the optimizing nitrogen rate for two potato varieties with different nitrogen use efficiency and reveal the coordination mechanisms of source and sink achieving high nitrogen efficiency.
The authors well descripted the dynamic of source (shoot weight) and sink (tuber weight) and calculated a lot of growth parameters by fitting β-Sigmoid growth model.
There were several flaws and question needed to be solved.
1. L123. Why the difference in basic soil nutrients was great among the three seasons?
2. L179-188. The all parameters in the model were needed to be explained clearly.
3. Figure 3. There were the data of tuber weight after 9/1. Why did not show shoot weight?
4. Table 2. What were the meanings of C and R?
5. Tables 4 and 5. The tma was short, just 1-9 days, under several treatments, but other treatments showed greatly differences. The reasons?
6. Figure 5. The study aims to discuss the mechanisms achieving N efficiency, thus the relationships of the N efficiency with source and sink should be analyzed.
7. The authors only analyzed the relationships of source and sink with the growth length of each development periods, and the growth strength should be analyzed.
8. Conclusion. In the Results, there was not the parameter of sink/source ratio. What is the meaning of this parameter?
9. Abstract. The description of results show lacks of logic and refinement.
10. Considering the yield, the efficient variety J could not reduce the application of N, but the inefficient variety Y could reduce due to the similar yield between 150 and 300 N rates. However, for NUE, the J and Y showed higher efficiency under 150 than under 300. The authors need to clearly explain the difference.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
General comments:
1、 There are too many errors in the format of references in the manuscript.
2、What are the highlights in this study?
3、What is the source-sink coordination mechanism of high efficiency nitrogen potato in the manuscript? Is it unclear in the manuscript?
Specific comments:
1. The authors need to check the English expression comprehensively to eliminate the influence of unreadability on the value of the manuscript.
2、There are errors in the test design method.
3、Basis for selecting two nitrogen application rates.
4、How are efficient and inefficient varieties defined? Additional references are needed.
5、Other comments to authors are given in the file of manuscript.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I have not found the revised version of the manuscript.
From the revision notes, the authors have generally addressed the issues raised in my last review, but there are still grammar issues in the manuscript, which needs to be further polished before accept for publication.
Reviewer 4 Report
Dear author，
You should have studied the comments carefully and made corresponding corrections by using the red text in the original manuscript. Point-by-point replies are listed in the “Response to reviewers”. Instead of just answering my questions. No traces of modifications were found in the latest manuscript.
Round 3
Reviewer 1 Report
No more comments
Reviewer 4 Report
You should have studied the comments carefully and made corresponding corrections by using the red text in the original manuscript. Point-by-point replies are listed in the “Response to reviewers”. Instead of just answering my questions.
