Varietal Variances of Grain Nitrogen Content and Its Relations to Nitrogen Accumulation and Yield of High-Quality Rice under Different Nitrogen Rates

Round 1

Reviewer 1 Report

Dear Editor

The manuscript called "Varietal variances of grain nitrogen content and its relations to nitrogen accumulation and yield of high-quality rice under different nitrogen rates" was reviewed. All comments were shown on the pdf file. The manuscript is not suitable for publication with its current status. But after revision based on corrections and suggestions, it can be published.

Sincerely yours

Comments for author File: Comments.pdf

Author Response

Dear Editors and Reviewers: Thank you for your comments on our manuscript entitled “Varietal variances of grain nitrogen content and its relations to nitrogen accumulation and yield of high-quality rice under different nitrogen rates”. These comments are all valuable and very helpful for revising and improving our manuscript, as well as for further guiding our research in future. We have studied these comments carefully and have made correction which we hope meet with approval. Revised parts were marked in red in manuscript. Please see the attachment. We highly appreciate for your hard work, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Reviewer 2 Report

Nitrogen (N) management is an important strategy for improving yield, grain quality and N use efficiency of rice (Oryza sativa). The main goal of this study was to study the varietal variances of grain nitrogen content and its relations to nitrogen accumulation and yield of high-quality rice under different nitrogen application rates. I think this study can provide reference for a reasonable N application rate for high-quality rice, which is of great significance. However, the manuscript has following question and suggestion, and numerous mistakes in the manuscript should be fully addressed before considering for publication.

1. English writing needs a lot of improvement, there are many mistakes in grammar throughout the manuscript. It is suggested to have a native English speaking person to help to edit the English writing.

2. In the Abstract section, some of the expressions are ambiguous. For instance, despite reading the authors' description, I am not really sure what the experimental design of this study is. What is the N fertilizer application schedule? And why weren't the N fertilizer application rates explained? What’s more, the main research objectives of this experiment is to explore the effect of different N fertilizer application rates on grain nitrogen concentration and yield of twenty representative high-quality rice varieties, therefore, it is suggested to supplement the yield and grain N concentration differences among various experimental treatments. 

3. In the Introduction section, the author did not well point out the gap of the literature the study seeks to fill and novelty of the study over the existing research. This point showed be further elaborated. In addition, the expected significance of the study is suggested to be supplemented at the end of the introduction.

4. In the Materials and Methods section

2.2. Experimental design

L116-117 Why 2 seedlings per hill for hybrid rice and 4 seedlings per hill for inbred rice?

L110-111 “The field experiments were arranged in a split-plot design with two replications in 2019 and three replications in 2020.” Two replication???

L129 Why there only 165 kg ha^-1 (N165) and 225 kg ha^-1 (N225)was selected?

2.3. Sampling and measurements

It is suggested that the investigated contents of this study should be described separately according to the contents measured in the results, and the calculated formula and the definition of indicators should be clear, such as the coefficient of variation (CV), grain setting rate, nitrogen utilization efficiency, etc. All indicators involved in the results should be described in detail here.

5. In Results section,  In this section, there is mainly some research data at maturity stage of rice, and no relevant mechanism research contents to support the authors experimental results, some photosynthetic physiology date of rice, dry matter production and other relevant study data are suggested to be supplemented in this section. In addition, the purpose of this study is to provide a theoretical basis for rational N fertilizer application of rice, so the difference in response of different varieties to N fertilizer application rates in the results should be described. For general or most varieties of rice, which N application amount can achieve the goal of high yield and high quality? Instead of over describing the general conclusions, the author should highlight the innovation points and important research results of this study.

6. The Discussion section should discuss and analyze the mechanism of the important findings obtained in this study, rather than re-description of the findings. The author should analyze and answer why there is such a phenomenon or result, and what is the reason for obtaining such a result?

7. The Conclusion section, the author is suggested to point out clearly what kind of varieties of rice and what amount of N fertilizer application rate can improve grain yield and quality simultaneously.

Author Response

Dear Reviewers: Thank you for your comments on our manuscript entitled “Varietal variances of grain nitrogen content and its relations to nitrogen accumulation and yield of high-quality rice under different nitrogen rates”. These comments are all valuable and very helpful for revising and improving our manuscript, as well as for further guiding our research in future. We have studied these comments carefully and have made correction which we hope meet with approval. Revised parts were marked in red in manuscript. Please see the attachment. We highly appreciate for your hard work, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Reviewer 3 Report

The present article can be a relevant study but several aspects need to be addressed.

The abstract should be shortened and made more concise.

One main issue are the combination of years in scatterplots/correlations. Variety differences must be valid within years. Secondly, N grain accumulation appears crucial in terms of environmental and economic effect. It is recommended to be included. In my understanding, cultivar/fertilization combination of high yield, moderate N content and maximum grain N uptake are to be found but strategies  for achieving this are not clearly shown. Acceptable N content should be definded.

Introduction

·         l. 43 pp: Sentence is not clear.

·         l.48: What is high quality rice and why related to people's living standard?

·         l. 62 is unclear. Please make clear quality and relation to N content. What is negative effect of high N content?

Material and Methods

·         What was the reason for selecting these two cultivars for additional investigation?

·         Please indicate date of transplanting.

·         Explain term "hill".

·         How valid are the statistics for the year with only two replicates?  Statistics on post hoc test/anova need to be described.

·         How representative are the cultivars for regional production? What are their release years? Why are inbreed cultivars included and how do they affect the results? Should be briefly discussed in discussion section.

·         2.2: An image of microplot setup with tubes would be helpful.

·         Explain 'hill'.

·         Calculation of grain setting rate must be described.

Results

·         What is the use for presenting CV? High variation is not indicative as such, especially across years.

·         Figure 1: Possibly consider splitting the figures by weather trait, not by year, for better year-wise comparison.

·         Table 2: More information on statistics applied are required. Color/Letter group coding would improve the comparability. Unit is missing. Superscript b is unclear.

·         The added benefit of cluster analysis is not clear, especially due to including only one parameter CV. It does not indicate high/low N content. Improved presentation of table 2 would provide grouping, too.

·         3.2 etc.:  Shorten numbers  (R²) to relevant two digits.

·         3.2 + Scatter plots: What is the use of analyzing both years together? The relationships within trials appears much more relevant to me. Especially in Fig. 4, correlations seem to be driven by year-specific differences only. Underlying years should be indicated and R² calculated within years (color/point type etc.)

·         Fig. 4: Explain grain setting rate.

·         Scatterplots: Axes should be the same.

·         Table 2 and 3: Which post hoc test was applied?

·         l. 269: revise wording 'improved'.

·         While N accumulation is presented for microplot experiments, why not for field experiments. In terms of environmental effect, it is the most important trait.

·         l. 272: revise wording

·         l. 271: Section should be improved: Writing is confusing.

·         Table. 4: Information on stat. test is required.

·          

Discussion

·         Confusing wording in l. 306 'improve'

·         L. 365 pp: Unclear sentence: increase in comparison to what?

·         Highest recovery rate of last dose and very low rate for first dose is surprising in comparison to wheat.

·         Why is recovery rate increased with more applied N?

·         It remains unclear if the presented level of N content is a quality issue.

·         Harvest index and grain N uptake/accumulation are hardly discussed.

 

Conclusions

Which strategies are recommended for increasing grain N accumulation, yield with acceptable N content?  Conclusions should go further the results.

 

General

·         Revise language: l. 37; l. 42: rice population quality?; l. 60; l. 318; etc.

 

 

Author Response

Dear Reviewers: Thank you for your comments on our manuscript entitled “Varietal variances of grain nitrogen content and its relations to nitrogen accumulation and yield of high-quality rice under different nitrogen rates”. These comments are all valuable and very helpful for revising and improving our manuscript, as well as for further guiding our research in future. We have studied these comments carefully and have made correction which we hope meet with approval. Revised parts were marked in red in manuscript. Please see the attachment. We highly appreciate for your hard work, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have revised as requested and I have no further suggestions for the manuscript to be published.

Reviewer 3 Report

The issues were addressed sufficiently.