Effects of Nitrogen Forms and Application Rates on Nitrogen Uptake, Photosynthetic Characteristics and Yield of Double-Cropping Rice in South China

Round 1

Reviewer 1 Report

The paper is well written and provides valuable evidence for how to improve N fertilizer management. I made minor suggestions. I would mainly just focus on making the tables and figures a bit more legible.

Comments for author File: Comments.pdf

Author Response

Responses 1:

 

Thank you for your suggestions. We have revised the manuscript according to your suggestions and hoped the revised manuscript would meet journal requests. The detailed corrections are listed below point by point.

Introduction

Point 1: Line 38: what does “ammonium-loving” mean? Like it will preferentially take up ammonium to nitrate?

Yes, your understanding is correct. Rice preferentially takes up ammonium-N rather than nitrate-N. We have revised them, please see lines 38, page 1

 

Materials and methods

Point 2: Line 97: why this leaf?

For rice, since the top leaf is an important functional leaf, we chose it and determined SPAD value of the leaf. In a previous study, they also chose the top leaf and determined the SPAD value, for details, please see Yang H.et. al. Effects of nitrogen application rate and leaf age on the distribution pattern of leaf SPAD readings in the rice canopy. Plos One 2014, 9, and we have added it into references.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Abstract

I propose to add an introductory sentence to the summary.     

Introduction

In the introduction, the authors write N fertilization, and in the summary: N nutrition, I propose to standardize or focus on N nutrition in the introduction.

I propose to add a working hypothesis to the introduction and to draw conclusions base on it.

2.1 Experimental conditions

I propose to attach a photo of the greenhouse with plastic fill-roof and gauze 54 with potted walls to show the experience pattern.

There is a lack of conditions in the greenhouse (temperature, humidity during the experiment). What about meeting water need/requirements?

2.2 Plant materials and treatments

Lack of sampling procedure for soil material, has the soil been broken down or taken directly intact before the experiment?

Consistency of fertilizers? How were they apply?

No data on the number of repetitions of the experiment.

The lack of described data on experimental factors (order of factors), which is undoubtedly the source of nitrogen, the rates and term of sowing.

Line 85-87.The management of diseases, pests and weeds is carried out in accordance with the local convetional methods for the prevention and control of rice diseases and pests - please explain.

2.3 Determination of rice dry weight and N uptake

No data on plant material sampling. No data on the temperature on determination of rice dry weight (give a method or a appropriate norm).

The Kjehdal method allows to determine the nitrogen content in the plant material, the nitrogen uptake was calculated on the basis of the yield and content - no such information is available. 

2.4 Determination of SPAD value

Expand the abbreviation SPAD.

Provide the date of measurement or phase.

Specify the significance level and the statistical programme used. Propose to separate the statistical analysis sub-section and write the tests used in the experiment.

3.1. Effects of N forms on leaf SPAD value and N content of rice seedlings

Line 126-128: too obvious to be included in the text.

Blurred figure 1. In the diagrams I also propose to mark the development phases of the plants according to the chosen scale with numbers.

I propose to define developmental phases based on international standards (e.g. BBCH Scale, which will make it easier for the reader to recognize them).

Line 144: Lack of the year of the publication

 

 

 

 

 

Comments for author File: Comments.pdf

Author Response

Responses 2:

 

Thank you for your suggestions. We have revised the manuscript according to your suggestions and hoped the revised manuscript would meet journal requests. The detailed corrections are listed below point by point.

 

Abstract

Point 1: I propose to add an introductory sentence to the summary.

Responses 1:

Thank you for your comment. We have added an introductory sentence to the summary, as shows as follows: "Nitrogen is an important element that affects the growth and yield of rice obviously".

 

Introduction

Point 2: In the introduction, the authors write N fertilization, and in the summary: N nutrition, I propose to standardize or focus on N nutrition in the introduction.

Responses 2:

Thank you for your comment. We have revised and standardized the expression pattern. Please see them in the introduction.

 

Point 3: I propose to add a working hypothesis to the introduction and to draw conclusions base on it.

Responses 3:

Thank you for your suggestion. We have added a working hypothesis. Please see line 52-53, Page 2.

 

Materials and methods

2.1 Experimental conditions

Point 4: I propose to attach a photo of the greenhouse with plastic fill-roof and gauze 54 potted walls to show the experience pattern.

Responses 4:

Please see the following photo, which was the picture of rice seedlings the jointing and booting stage in the greenhouse.

 

Point 5: There is a lack of conditions in the greenhouse (temperature, humidity during the experiment).

Responses 5:

Thank you for your comment. We have described them in line 82-84, page 2.

 

Point 6: What about meeting water need?

Responses 6:

Thank you for your comment. The rice seedlings were watered each day, and the depth of water layer was kept 2 cm.

 

2.2 Plant materials and treatments

 

Point 7: Lack of sampling procedure for soil material, has the soil been broken down or taken directly intact before the experiment?

Responses 7:

Thank you for your comment. The test soil was taken from paddy soil field. Then the soil was dried, crushed, mixed and sieved prior to filling into the pots. We have revised them in line 65, page 2.

 

Point 8: Consistency of fertilizers? How were they apply?

Responses 8:

Thank you for your comment. The total amount of N fertilizer applied is divided into base fertilizer, tiller fertilizer and spike fertilizer at the ratio of 4:4:2. Base fertilizer was mixed with test soil before filling into the pots. Tiller fertilizer and spike fertilizer were applied by topdressing.

 

Point 9: No data on the number of repetitions of the experiment.

Responses 9:

Thank you for your reminding. We have added the number of replicates of the experiment in the manuscript, please refer to line 76 for details.

 

Point 10: The lack of described data on experimental factors, which is undoubtedly the source of nitrogen, the rates and term of sowing.

Responses 10:

Thank you for your reminding. We have described them, please see paragraphs 2 and 3 of section 2.2.

 

Point 11: Line 85-87. The management of diseases, pests and weeds is carried out in accordance with the local conventional methods for the prevention and control of rice diseases and pests - please explain.

Responses 11:

Thank you for your questions. We used local farmer’s method to deal with plant diseases, insect pests and weeds. Rice diseases and pests including rice blast, striped rice borer, etc were dealt with pesticides on the market. Weeds were cut artificially.

 

2.3 Determination of rice dry weight and N uptake

Point 12: No data on plant material sampling. No data on the temperature on determination of rice dry weight (give a method or a appropriate norm).

Responses 12:

Thank you for providing these insights. We included this suggestion, please see lines 94-101 of the paper.

 

Point 13: The Kjeldahl method allows to determine the nitrogen content in the plant material, the nitrogen uptake was calculated on the basis of the yield and content - no such information is available.

Responses 13:

Thank you for your advice. We have made changes, please see lines 102-107.

 

2.4 Determination of SPAD value

 

Point 14: Expand the abbreviation SPAD. Provide the date of measurement or phase.

Responses 14:

Thank you for your comment. We have added the full name of SPAD, please see line 109, and lines 111-112.

 

Point 15: Specify the significance level and the statistical programme used. Propose to separate the statistical analysis sub-section and write the tests used in the experiment.

Responses 15:

Thank you for your comment. We have made changes, please see lines 131-134.

 

3.1. Effects of N forms on leaf SPAD value and N content of rice seedlings

 

Point 16: Line 126-128: too obvious to be included in the text.

Responses 16:

Thank you for your comment. We have deleted lines 126-128 from the manuscript.

 

Point 17: Blurred figure 1. In the diagrams I also propose to mark the development phases of the plants according to the chosen scale with numbers.

Responses 17:

Thank you for your comment. I'm very sorry for our mistakes. We have revised them and replaced a clear picture.

 

 

Point 18: I propose to define developmental phases based on international standards (e.g. BBCH Scale, which will make it easier for the reader to recognize them).

Responses 18:

Thank you for your comment. We have modified them, please see Section 2.3 and cited references.

 

Point 19: Line 144: Lack of the year of the publication

Responses 19:

Thank you for your comment. We have added the year of the publication to the manuscript, please see line 144.

 

Author Response File: Author Response.docx