Nitrogen Uptake, Use Efficiency, and Productivity of Nigella sativa L. in Response to Fertilization and Plant Density

Round 1

Reviewer 1 Report

This is an interesting study and the authors have done extensive experiments. However, some issues need to be resolved because the results and discussion are not well represented.

1. Please standardise the use of above-ground or aboveground (line 94, 158)
2. Line 186 and Table 2...Please standardise the use of seed N yield or seed N Uptake? The write-up in the Results and the label on Table 2 is not similar. (Please check the other table as well)
3. Line 189-190….biomass N content, biomass N yield, total plant N uptake are not statistically significant (based on Table 2), but you mentioned differently in the write-up. Please check…
4. Your write-up in the Results does not agree with the Table. Please check all the numbers/percentages (eg. Line 213.... You mentioned about 2.11% and 2.06%, but the percentage is not similar to the Table 3). The same comments apply to all other numbers and percentages used in the Results and Table (line 230, line 232, line 237, line 242-243… etc.)
5. Line 392… You mentioned about “23% higher”. Where can I get this percentage in the table? The same comment goes to line 450, line 466, line 531, line 552 and line 568 on the percentage used (40.4%; 76.8%; 71%; 93.18%, 88.85% ,55.58%; and 101.9% , 82.6%)
6. Line 443 and line 463… The data on “dry matter” must be shown in the manuscript because it is an important finding
7. Line 479… The values ranged from 1476-1630 g is not accurate (based on Table). Please check
8. Line 514… Which table are you referring to? Please state in the manuscript
9. Repetition of paragraph (line 524 – 535) and (line 536-547)

Author Response

Reviewer 1

This is an interesting study and the authors have done extensive experiments. However, some issues need to be resolved because the results and discussion are not well represented.

Response: We thank the reviewer for the positive comments on our study and for the interesting information useful for improving it. We also double-checked the language of the text.

Comments

1. Please standardise the use of above-ground or aboveground (line 94, 158)

Response: We standardized the use of above-ground in our manuscript. The change was marked up using the “Track Changes” function.

2. Line 186 and Table 2...Please standardise the use of seed N yield or seed N Uptake? The write-up in the Results and the label on Table 2 is not similar. (Please check the other table as well).

Response: We standardized the use of seed N uptake in our manuscript. The change was marked up using the “Track Changes” function. 

3. Line 189-190....biomass N content, biomass N yield, total plant N uptake are not statistically significant (based on Table 2), but you mentioned differently in the write-up. Please check...

Response: We revised this sentence as the reviewer's request. (“In addition, the main effect of year was statistically significant on soil total nitrogen (STN), plant height, seed N content and N utilization efficiency (NUtE)”). The change was marked up using the “Track Changes” function.

4. Your write-up in the Results does not agree with the Table. Please check all the numbers/percentages (eg. Line 213.... You mentioned about 2.11% and 2.06%, but the percentage is not similar to the Table 3). The same comments apply to all other numbers and percentages used in the Results and Table (line 230, line 232, line 237, line 242-243... etc.)

Response: All the tables of the manuscript were revised and now they also contain the data of main factors means, where the results and discussion are based. The changes were marked up using the “Track Changes” function.

5. Line 392... You mentioned about “23% higher”. Where can I get this percentage in the table? The same comment goes to line 450, line 466, line 531, line 552 and line 568 on the percentage used (40.4%; 76.8%; 71%; 93.18%, 88.85% ,55.58%; and 101.9%, 82.6%)

Response: All the tables of the manuscript were revised and now they also contain the data of main factors means, where the results and discussion are based.

6. Line 443 and line 463... The data on “dry matter” must be shown in the manuscript because it is an important finding.

Response: The data on dry matter are presented in our previous work: Roussis, I., Kakabouki, I., Tsiplakou, E., Bilalis, D. (2020). Influence of Plant Density and Fertilization on Yield and Crude Protein of Nigella sativa L.: An Alternative Forage and Feed Source. In: Berghuis, S. (Ed.), Nigella sativa: Properties, Uses and Effects, Nova Science Publishers, Inc., Hauppauge, NY, USA. pp. 145-180., where the dry matter yield and quality of N. sativa as a forage crop was evaluated. 

7. Line 479... The values ranged from 1.476-1.630 g is not accurate (based on Table). Please check

Response: All the tables of the manuscript were revised and now they also contain the data of main factors means, where the results and discussion are based. This sentence is based on the thousand seed weight of fertilization means.

8. Line 514... Which table are you referring to? Please state in the manuscript.

Response: We revised this sentence as the reviewer's request. (“In terms of fertilization, the highest average three-year values were recorded in inorganic fertilization and compost, with the values being 97.9% and 82.9% higher than the control, respectively (Table 8).”) 

9. Repetition of paragraph (line 524 – 535) and (line 536- 547)

Response: We deleted the repetition of this paragraph according to the reviewer's request. The change was marked up using the “Track Changes” function.

Reviewer 2 Report

Due to different treatments of fertilization it would be usefull to measure also:

1. The content of the other nutrients in the soil and the plants also
2. The production and the quality of the volatile oils.

Author Response

Reviewer 2

We thank the reviewer for the positive comments on our study and for the interesting information useful for improving it. We also double-checked the language of the text.

Comments

Due to different treatments of fertilization it would be usefull to measure also:

1. The content of the other nutrients in the soil and the plants also
2. The production and the quality of the volatile oils.

Response to comments 1 and 2: Unfortunately, there is no available data on the content of the other nutrients as well as the production and quality of volatile oil. However, we would like to inform you that during this period our research team is preparing new experiments on N. sativa crop, where the effect of phosphorus, as well as the quality of fixed and volatile oils of this crop species, will be evaluated.

Reviewer 3 Report

1.  All p values used in the Discussion (drom page 13 on) contain 2 faults: (a) all values are too low by 10⁻¹, (b) the named statistical borders are included therefore the lowest levels of statistical grouping has to be named as.

2.  The tables are very detailed by providing the complete set of means per year of cultivation. Within the text means over all years of cultivations are used for further discussion which is highly problematic. As example: it demands individual calculation by the reader to understand where a figure of 696 kg is derived of (p. 15 line 456). he has to find data in Table 4, section Seed Yield and extract the all data for Inorganic and to determine the mean. [Typical task of the writing crew]

3.  All tables offers indications about statistical differences, the Yes or No options. But it is not clear where these differences can be found; with concern to interactive effects data exist at the table, with concern to data of main factors means are missing.

4.  It would be extremely helpful, not to speak: recommendable to improve tables by working with overall means and including their codations derived by the Tukey’s HSD. Thus statistics would be more conclusive, data for further discussions transparable.

5.  The dominace of 7 tables, with high density of data, and structured by the similar design creates impressions of monotony. In order to break this slightly negative touch a mixture of tables and graphs could be an easy improvement.

6.  For a better readibilty of Table 8 the axes of the table should be changed by 90°.

7.  The focus of the paper is mainly N provision and plant density. Therefore it is slightly irritating that the amount of N applied through the various fertilizers misses any precise figure. The N content of the compost used is obviously originated by the commercial informations about nutrient contents (1-2 % N) and does not meet scientific requirements for academic trials. What is the precise amount of N applied per ha⁻¹? That has to be added to the corresponding subchapter of Methods & Materials.

Author Response

Reviewer 3

We thank the reviewer for the positive comments on our study and for the interesting information useful for improving it. We also double-checked the language of the text. 

Comments

1. All p values used in the Discussion (drom page 13 on) contain 2 faults: (a) all values are too low by 10−1, (b) the named statistical borders are included therefore the lowest levels of statistical grouping has to be named as.

Response: We changed according to the reviewer's request. The changes were marked up using the “Track Changes” function.

2. The tables are very detailed by providing the complete set of means per year of cultivation. Within the text means overall years of cultivations are used for further discussion which is highly problematic. As example: it demands individual calculation by the reader to understand where a figure of 696 kg is derived of (p. 15 line 456). he has to find data in Table 4, section Seed Yield and extract the all data for Inorganic and to determine the mean. [Typical task of the writing crew]
3. All tables offers indications about statistical differences, the Yes or No options. But it is not clear where these differences can be found; with concern to interactive effects data exist at the table, with concern to data of main factors means are missing.
4. It would be extremely helpful, not to speak: recommendable to improve tables by working with overall means and including their codations derived by the Tukey’s HSD. Thus statistics would be more conclusive, data for further discussions transparable.

Response to comments 2, 3 and 4: Concerning the table, we have to inform you that all of them revised and now they also contain the data of main factors means according to the reviewer's request. The changes were marked up using the “Track Changes” function.

5. The dominace of 7 tables, with high density of data, and structured by the similar design creates impressions of monotony. In order to break this slightly negative touch a mixture of tables and graphs could be an easy improvement.

Response: We changed according to the reviewer's request. Now, the results of seed yield are presented in a graph (Figure 2).

6. For a better readibilty of Table 8 the axes of the table should be changed by 90°.

Response: We would like to inform you that we follow the guidelines of the Journal for this Table.

7. The focus of the paper is mainly N provision and plant density. Therefore, it is slightly irritating that the amount of N applied through the various fertilizers misses any precise figure. The N content of the compost used is obviously originated by the commercial informations about nutrient contents (1-2 % N) and does not meet scientific requirements for academic trials. What is the precise amount of N applied per ha⁻¹? That has to be added to the corresponding subchapter of Methods & Materials.

Response: According to the reviewer's request, we add a Table presenting the plant density and fertilization methods used in the study.

Round 2

Reviewer 1 Report

A well-written manuscript and a lot of improvements from the previous version.

Author Response

Reviewer 1

A well-written manuscript and a lot of improvements from the previous version.

Response: We thank the reviewer for the positive comments on our study and for the interesting information useful for improving it.

Reviewer 3 Report

look into the attached file

Comments for author File: Comments.pdf

Author Response

Reviewer 3

We thank the reviewer for the positive comments on our study and for the interesting information useful for improving it. 

Comments to the revised paper

1. Table 2 is overloaded by redundant text. Therefore reduce it to the figures and combine the two identical parts of plants densitiy to one. Replace the column by , , and .

Response: We changed according to the reviewer's request. The changes were marked up using the “Track Changes” function.

2. The graphical approach of one parameter is a real improvement and should be expanded for more parameters. The statistical codations of the figure 2 are missing in all data tables. Why?

3. A ‘minimal compromise’: I recommend to change data tables according to the same scheme as done for figure 2.

Response to comments 2 and 3: Concerning the tables, we have to inform you that all of them revised and now they also contain the statistical codations according to the reviewer's request. (The capital letters denote statistically significant differences according to the Tukey’s HSD test (p ≤ 0.05) under different plant density, and lowercase letters denote statistically significant differences according to the Tukey’s HSD test (p ≤ 0.05) under different fertilization.) The changes were marked up using the “Track Changes” function.

4. General comment: What was the reason for a higher level of N by the application of inorganic fertilizer compared to the organic fertilizers? At least the falling tendencies by the use of manure (applied N only 2/3 of the applied N by inorg. fertilizer or compost) could be linked to that fact. A final reflection of the data should include such an aspect.

Response: It is now explained according to the reviewer's request. (“The amount of each type of fertilizer used in the current experiment is the general recommended dose of the corresponding type of fertilizer for N. sativa production in clay-loam soils [3,12].” in the Materials and Methods section). The discussion strongly agreed and explained the results of the current study.