The Effect of Nitrogen Reduction at Different Stages on Grain Yield and Nitrogen Use Efficiency for Nitrogen Efficient Rice Varieties
Round 1
Reviewer 1 Report
Comments for Authors
”The Effect of Nitrogen Reduction at Different Stages on Grain Yield and Nitrogen Use Efficiency for Nitrogen Efficient Rice Varieties”
The subject is interesting and fall within the scope of the journal. The subject of the article is included in the section "Farming Sustainability". The subject matter is interesting and little reported in scientific articles. I positively assess the performance of the experiment in field conditions. The Authors examined effects of nitrogen reduction at different stages on grain yield and nitrogen use efficiency for nitrogen efficient rice varieties. The experimental dataset undoubtedly are useful experiments. The scientific manuscript has scientific merit and quality to be published, enabling great information for the scientific community and farming practices. The following points may be addressed by the Authors to enhance the usefulness of the paper.
Abstract
I have no objections.
Keywords
Correct selection.
Introduction
The review of known test results was performed correctly. The research hypothesis and research goals were formulated correctly.
Materials and Methods
The soil classification according to the WRB should be completed.
Climatic data should be completed (do they concern the entire vegetation period or a month?)
The units for fertilizer doses should be correctly recorded, according to publishing requirements.
Write down the doses of phosphorus and potassium in the pure component (P and K) or (P2O5 and K2O). Specify the P i K content in the fertilizers used.
Results
The results were presented correctly.
Discussion
The discussion of the results was carried out correctly.
Conclusions
The summary needs to be improved. Present exactly what are the conclusions of the research. Give further research directions on this topic. In my opinion, fertilization research should be conducted not only in terms of the amount of rice grain yield, but also its quality.
References
DOI numbers are missing .....
Author Response
1.The soil classification according to the WRB should be completed.
We have added this in the text, "The soil was a sandy loam [Typic Fluvaquents, Etisols (U.S. taxonomy)]".
2.Climatic data should be completed, do they concern the entire vegetation period or a month?
The average precipitation, sunshine hours, and mean air temperature concerned the entire vegetation period were 126 mm, 194 hours, and 25.1°C, respectively in 2017 and 145 mm, 183 hours, and 24.7°C, respectively in 2018.
Because the meteorological data are in the same location as another published paper, Ju, C.; Liu, T.; Sun, C. Panicle nitrogen strategies for nitrogen-efficient rice varieties at a moderate nitrogen application rate in the lower reaches of the Yangtze river, China. Agronomy 2021, 11, 192. https://doi.org/10.3390/agronomy11020192. To avoid duplication, one concern the entire vegetation period, and another one concern each month.
3.The units for fertilizer doses should be correctly recorded, according to publishing requirements. Write down the doses of phosphorus and potassium in the pure component (P and K) or (P2O5 and K2O). Specify the P i K content in the fertilizers used.
Phosphorus was applied as calcium super-phosphate (13.5% P2O5) at a rate of 150 kg hm−2 before transplanting, potassium was applied as potassium chloride (52.0% K2O) at a rate of 150 kg hm-2 and split at 1 d before transplanting and panicle initiation.
4.Give further research directions on this topic. In my opinion, fertilization research should be conducted not only in terms of the amount of rice grain yield, but also its quality.
We have added this in the text, "Further research is needed to understand not only the grain yield and NUE, but also the grain quality mechanisms underlying N uptake, assimilation and remobilization of N-efficient varieties."
5.References DOI numbers are missing .....
We have added DOI numbers in the text.
Your good advice was very much appreciated.
Best regards,
Chengxin Ju
Author Response File: 
Author Response.docx
Reviewer 2 Report
Title: The effect of nitrogen reduction at different stages on grain yield and nitrogen use efficiency for nitrogen efficient rice varieties
Abstract: Need a strong hypothesis of the experiment
Introduction: What is the background information of the experiment?? Need to present some related data
How varietal experiment is needed for the experiment and add environmental concerns, Add clear objective and hypothesis at the end of the introduction.
M & M: Need to add some related references for the methodology used
Discussion must be supported with the same article tables and figs
Concussion should be in bullet after a para
Overall, a need to improve the article to make a strong presentation for the international society
Author Response
- Abstract: Need a strong hypothesis of the experiment.
We have changed the text and marked in red. The reduction of nitrogen (N) fertilizer during the rice growing season is an important practice in rice production that is ecologically beneficial. Will different N reduction stages affect rice yield and NUE? The timing of reduction for N-efficient varieties (NEVs) is yet to be identified, especially under moderate N rates application.
- Introduction: What is the background information of the experiment?? Need to present some related data.
We have added this in the text, "Rice yield in the world has continuously increased in the last 60 years, partly because of the increase in fertilizer-N input. However, the use of N fertilizer is generally inefficient, and the problem of low NUE is more aggravated in China.".
- How varietal experiment is needed for the experiment and add environmental concerns, Add clear objective and hypothesis at the end of the introduction.
The relevant contents are marked in red in the text.
The experiments were laid out in a split-plot design with N reduction treatments as main plots and varieties as subplots with three replicates.
The average precipitation, sunshine hours, and mean air temperature concerned the entire vegetation period were 126 mm, 194 hours, and 25.1°C, respectively in 2017 and 145 mm, 183 hours, and 24.7°C, respectively in 2018.
The objective was to investigate the changes of grain yield and NUE of NEVs under different N reduction treatments and to understand their agronomic and physiological basis. Our purpose was to identify an appropriate N reduction timing and to provide a reference for the scientific reduction of fertilizer-N.
- Need to add some related references for the methodology used.
The related references have been marked in red in the text.
- Discussion must be supported with the same article tables and figs.
We have examined the tables and figs and make sure that discussion were supported with the same article tables and figs.
- Concussion should be in bullet after a para. Overall, a need to improve the article to make a strong presentation for the international society.
We have added this in the text. "Further research is needed to understand not only the grain yield and NUE, but also the grain quality mechanisms underlying N uptake and assimilation of N-efficient varieties."
Your good advice was very much appreciated.
Best regards,
Chengxin Ju
Author Response File: Author Response.docx
