Delaying Application and Reducing the N Rate Enhances Grain Yield and N Use Efficiency in No-Tillage, Direct-Seeded Hybrid Rice
Round 1
Reviewer 1 Report
In general, the article is devoted to the relevant topic of increasing rice yields with minimal damage to the environment and labor costs. The article presents the results of experimental studies of the effect of different doses of fertilizers on the yield of two rice hybrids.
Meanwhile:
- it is necessary to supplement the justification for the choice of nitrogen doses (lines 136 - 139);
- it is necessary to supplement the formulas with references to literary sources (lines 174, 175, 176);
- it is possible to translate part of the data from tables 2-4 into a graphical form, which would make the information clearer to understand;
- conclusions can be expanded taking into account the presented results.
Author Response
Dear Reviewers:
We would like to thank you for the constructive comments, which greatly helped to improve the quality of our manuscript. We have modified the manuscript according to the reviewers’ suggestions. All changes are marked in red in the manuscript, and our point-by-point responses are listed below.
It is necessary to supplement the justification for the choice of nitrogen doses (lines 136 - 139);
Response: The choice of nitrogen doses was according to our previous study. Reducing N rate from 225 to 150 kg N ha-1 without sacrificing grain yield while increasing the AEN, PFPN, and REN in the direct seeded rice cropping system [15]. The following statements have been added in the this section: The nitrogen doses was determined according to our previous study. (P3, L138-141)
It is necessary to supplement the formulas with references to literary sources (lines 174, 175, 176);
Response: We have added the formulas with references to literary sources. (P4, L176-178)
It is possible to translate part of the data from tables 2-4 into a graphical form, which would make the information clearer to understand;
Response: Thank you for reviewer’s suggestion! In fact, using graphical form make the information clearer to understand. However, it is not easy to translate part of the data from tables 2-4 into a graphical form, because the tables included the three factors of year, treatment and cultivar as well as the analysis of variance, which need more graphical forms if the graphical forms are used.
Conclusions can be expanded taking into account the presented results.
Response: We have been revised the manuscript according to the reviewer’s suggestion.(P11, L415-417)
The revised manuscript has been submitted to your journal. We look forward to your positive responses. Thank you very much and best regards.
Sincerely yours,
Peng jiang
Rice and Sorghum Research Institute, Sichuan Academy of Agricultural Sciences
Deyang 618000, China
FuXian Xu
Rice and Sorghum Research Institute, Sichuan Academy of Agricultural Sciences
Deyang 618000, China
Author Response File: 
Author Response.doc
Reviewer 2 Report
General Comments: This manuscript would provide a good contribution to the literature in the development of alternative rice production systems in China. The research question is beneficial in multiple aspects. In general, the manuscript is well written, the exception being the Results section. The Results section is very tedious to read and repetitive as data in the text is only presented in terms of percentage comparisons. Data presented in the tables is also very repetitive as every measured response variable is identically presented. Large tables of data, such as shown here, make it difficult to discern trends. In addition, there are several interpretations that are incorrect, e.g., stating that a certain treatment yields greater than another treatment when one has an “b” letter grouping and the other a “ab”. Overall, this is a good research question, but some of the concerns should be addressed.
Line 132: What was the N source?
Line 137: Please clarify if the N treatments are shown in kg N ha-1 or kg fertilizer ha-1.
Lines 184-188: The statistical analysis information is the bare minimum to convey what type of analysis was performed. More information is needed to justify why results are presented as they were, why certain comparisons were made or not made, etc. For instance, it is assumed that year was considered a fixed effect in the ANOVA and that years were statistically different because year is always shown separately; however, additional information confirming that year was considered fixed and why this was selected instead of year being random would provide meaningful information.
Lines 184-188: The authors may consider normalizing treatments to the N0 treatment. In doing so, they would retain the structure of their main plot factor as a 2 x 2 factorial, which would then allow them to pool over either the N rate factor or N split factor as appropriate, thus giving much greater inference power to the experiment.
Lines 210, 264, 295: For each of these sections, it would be very beneficial to have an ANOVA table showing the significance of each factor on each response variable. For example, the reader is left to assume from the presentation of data that the interaction of N treatment and rice hybrid was statistically significant for every response variable because the data is never shown pooled over hybrids or N treatments.
Line 215: From the analysis results shown in Table 1, it is incorrect to say that for N180 the R2 was greater than R1 because for both 2020 and 2021, N180, R2 has an “ab” letter group and N180, R1 has a “b” letter group. Similarly, or both 2020 and 2021, N153, R2 has an “a” letter group and N153, R1 has an “ab” letter group.
Lines 218 – 219: There is no p-value to back up this statement. We don’t even know if you tested for a year effect. If you tested for a year effect.
Lines 231-249: Very hard to read due to repetitive nature.
Lines 231-238: Panicles per m2, spikelets per panicle, average number of spikelets per m2, and average percentage of grain filling are all discussed pooled over N rates; however, the statistical analysis as shown does not support these comparisons. If the authors normalized the treatments to N0 as suggested above, then it may be true that there is no N rate x N split interaction and the main effect of N rate is significant, which would then let these comparisons be made statistically.
Lines 266-269: Where are the ANOVA results showing that you can statistically pool across years, cultivar, and N splits as you discuss here?
Lines 268-283: Very hard to read due to repetitive nature.
Lines 297-313: Very hard to read due to repetitive nature.
Lines 326-332: This is the introduction all over again. Why have another mini-introduction?
Lines 340-346: This is again a mini-introduction. Why is it necessary? It is just filler and does not add to the discussion.
Author Response
Dear Reviewers:
We would like to thank you for the constructive comments, which greatly helped to improve the quality of our manuscript. We have modified the manuscript according to the reviewers’ suggestions. All changes are marked in red in the manuscript, and our point-by-point responses are listed below.
Line 132: What was the N source?
Response: The urea was used for N source in the present study. The following statements have been added in the this section: the urea was used as N source. (P3, L140)
Line 137: Please clarify if the N treatments are shown in kg N ha-1 or kg fertilizer ha-1.
Response: We have checked the unit of the N treatment, and the N treatments is shown in kg N ha-1. (P3, L139)
Lines 184-188: The statistical analysis information is the bare minimum to convey what type of analysis was performed. More information is needed to justify why results are presented as they were, why certain comparisons were made or not made, etc. For instance, it is assumed that year was considered a fixed effect in the ANOVA and that years were statistically different because year is always shown separately; however, additional information confirming that year was considered fixed and why this was selected instead of year being random would provide meaningful information.
Response: Thank you for reviewer’s suggestion! We have revised the manuscript according to the reviewer’s suggestion. The comparisons were mainly made between two receiving nitrogen treatments, or two N split-application ratios in the present study. The N0 treatment was used as a CK treatment. The grain yield and nitrogen uptake in the N0 treatment was used to calculated the agronomic efficiency of applied N (AEN) and the recovery efficiency of applied N (REN), respectively. We have been deleted the comparisons between N0 and the other two N treatments in the manuscript. (P4, L190-197)
Lines 184-188: The authors may consider normalizing treatments to the N0 treatment. In doing so, they would retain the structure of their main plot factor as a 2 x 2 factorial, which would then allow them to pool over either the N rate factor or N split factor as appropriate, thus giving much greater inference power to the experiment.
Response: Thank you for reviewer’s suggestion! In the present study, the N0 treatment, which did not receive N, was used as a CK treatment. The agronomic efficiency of applied N (AEN) was calculated by the ‘difference method’ using the yield of the no-N plot, and the recovery efficiency of applied N (REN) was also calculated by the ‘difference method’ using the nitrogen uptake of the no-N plot. If the N0 treatment is removed, the AEN and REN will not be calculated. (P4, L190-197)
Lines 210, 264, 295: For each of these sections, it would be very beneficial to have an ANOVA table showing the significance of each factor on each response variable. For example, the reader is left to assume from the presentation of data that the interaction of N treatment and rice hybrid was statistically significant for every response variable because the data is never shown pooled over hybrids or N treatments.
Response: We have been added the ANOVA in the table 2, 3, 4 and 5. The AVOVA statistical model included replication, year (Y), treatments (including N0 and four combinations of two N rate and two N split-application ratios, T) , cultivar (C), the two-factor interactions of Y×T, Y×C, and T×C, and the three-factor interaction of Y×T×C. (P5, L220-221; P6, L239-240; P7, L267-269; P8, L292-294; P9, L301-303)
Line 215: From the analysis results shown in Table 1, it is incorrect to say that for N180 the R 2 was greater than R1 because for both 2020 and 2021, N180, R2 has an “ab” letter group and N180, R1 has a “b” letter group. Similarly, or both 2020 and 2021, N153, R2 has an “a” letter group and N153, R1 has an “ab” letter group.
Response: We have been revised the manuscript according to the reviewer’s suggestion. (P5, L221-229)
Lines 218 – 219: There is no p-value to back up this statement. We don’t even know if you tested for a year effect. If you tested for a year effect.
Response: We have been added the ANOVA in the table 3. We have been revised the manuscript according to the reviewer’s suggestion. (P6, L240-256)
Lines 231-249: Very hard to read due to repetitive nature.
Response: We have been revised the manuscript according to the reviewer’s suggestion. (P6, L240-256)
Lines 231-238: Panicles per m2, spikelets per panicle, average number of spikelets per m2, and average percentage of grain filling are all discussed pooled over N rates; however, the statistical analysis as shown does not support these comparisons. If the authors normalized the treatments to N0 as suggested above, then it may be true that there is no N rate x N split interaction and the main effect of N rate is significant, which would then let these comparisons be made statistically.
Response: We have been revised the manuscript according to the reviewer’s suggestion. (P6, L240-256)
Lines 266-269: Where are the ANOVA results showing that you can statistically pool across years, cultivar, and N splits as you discuss here?
Response: We have been added the ANOVA in the table 4. We have been revised the manuscript according to the reviewer’s suggestion. (P7, L269-276)
Lines 268-283: Very hard to read due to repetitive nature.
Response: Thank you for reviewer’s suggestion! We have been revised the manuscript according to the reviewer’s suggestion. (P7, L269-276)
Lines 297-313: Very hard to read due to repetitive nature.
Response: Thank you for reviewer’s suggestion! We have been revised the manuscript according to the reviewer’s suggestion. (P8, L293-297)
Lines 326-332: This is the introduction all over again. Why have another mini-introduction?
Response: Thank you for reviewer’s suggestion! We have been deleted the sentences. (P10, L320-321)
Lines 340-346: This is again a mini-introduction. Why is it necessary? It is just filler and does not add to the discussion.
Response: Thank you for reviewer’s suggestion! We have been deleted the sentences. (P10, L327-329)
The revised manuscript has been submitted to your journal. We look forward to your positive responses. Thank you very much and best regards.
Sincerely yours,
Peng jiang
Rice and Sorghum Research Institute, Sichuan Academy of Agricultural Sciences
Deyang 618000, China
FuXian Xu
Rice and Sorghum Research Institute, Sichuan Academy of Agricultural Sciences
Deyang 618000, China
Author Response File: Author Response.doc
Round 2
Reviewer 2 Report
Authors have addressed all concerns. No further comments.
