Review Reports - Potassium Increases Nitrogen and Potassium Utilization Efficiency and Yield in Foxtail Millet

Round 1

Reviewer 1 Report

The manuscript " Potassium increases nitrogen and potassium utilization efficiency, and foxtail millet yield” is interesting. In this manuscript, the authors investigate the effects of K application on biomass, yield, nutrient absorption, transportation, utilization of millet, dry matter accumulation, N and K accumulation and utilization, N metabolism, enzyme activity, and yield. The paper is good, The purpose of the study is clear, the method is feasible, the conclusion is reliable, and it is recommended to publish after minor revision.

The language is poor, must be revised by the native English speaker.

L10-12, the sentence is too long, I suggest dividing it into several short sentences

The abstract is too long.

Keywords should be revised, because many words and titles are repeated.

L96, add references.

Line 451: Here, you should add more references, such as (https://doi.org/10.1016/j.soilbio.2022.108714) and (doi:10.3390/su12104125).

Why are some values missing from Table 2.

English very difficult to understand/incomprehensible

Author Response

Response to Reviewer 1 Comments

Thank you very much for your comments, which make me to renew revise our manuscript to improve its structure and discourse in order to more reasonable and the conclusion clear. We made a lot of modifications according to the comments, marked them in red font in the revised paper.

Point 1: The language is poor, must be revised by the native English speaker.

Response 1: The revised version has been revised by Editage (Certificate_of_editing). And the new version has been re-revied by editage.

Point 2: L10-12, the sentence is too long, I suggest dividing it into several short sentences.

Response 2: After modification，the sentence (Line10-12) has been modified to “Field experiments were conducted to investigate the effects of K application on nitrogen and potassium utilization efficiency and yield of foxtail millet (Setaria italica L.). The experiment was performed in a completely randomized design with two millet cultivars (Jingu 21 and Zhangza 10) and five K₂O rates (0, 60, 120, 180, and 240 kg/hm²) in 2020 and 2021.”(Line 10-13)

Point 3: The abstract is too long.

Response 3: The abstract has been refined after modification.

Point 4: Keywords should be revised, because many words and titles are repeated.

Response 4: After modification, the key words are modified to: Foxtail millet, Potassium, Dry matter, Nitrogen metabolism, utilization efficiency, yield. (Line 30-31).

Point 5: L96, add references.

Response 5: Reference [25] has been added to the L96. (Line 86).

Point 6: Line 451: Here, you should add more references, such as (https://doi.org/10.1016/j.soilbio.2022.108714) and (doi:10.3390/su12104125).

Response 6: Reference [33-34] has been added to the L451. (Line 420)

Point 7: Why are some values missing from Table 2.

Response 7: According to formula “Agronomic efficiency of K fertilizer (AEK, kg/kg) = (grain yield receiving K application - grain yield receiving no K application) / K application rate.” Under K₀ treatment, valid values cannot be calculated, so there are some values missing in Table 2.

Reviewer 2 Report

The manuscript describes carefully conducted experiments, and the data analysis is very detailed. The research evaluates the effects of potassium fertilization on nitrogen and potassium utilization efficiency, and yield. The results are interesting from a scientific point of view and the authors were able to scientifically meet the proposed objectives. However, the manuscript has several limitations requiring attention.

1. The format of ordinate units in the fig. 9 shall be consistent. g^-1·FW·h^-1 (NR) and /(mg protein·h) (GS).

2. In Fig. 3 -Fig. 6, and fig. 8, only the data of K0 and K180 are provided, while data for K60, K120, K240, etc. are not provided. I think all data should appear in the manuscript. If you feel that the data is too large in the diagram, you can submitting it in the form of an attachment. Additionally, there are “(Supplementary Table 1- Supplementary Table 7)” in the manuscript, but Table data not provided in Supplementary.

3. Line 322: the Sentences “SS, JS, BS, FS, and MS are foxtail developmental stages.” is redundant, please delete it.

4. Line 536-537: and Zhangza 10 is K absorptive ability cultivar with higher K concentration without K application and greater roots. Modify to: and Zhangza 10 is K absorptive ability cultivar with greater roots and higher K concentration without K application.

Minor editing of English language required

Author Response

Response to Reviewer 2 Comments

Point 1: The format of ordinate units in the fig. 9 shall be consistent. g^-1·FW·h^-1 (NR) and /(mg protein·h) (GS).

Response 1: After modification, we have made the units in Figure 9 consistent, i.e, NR: µgNO2-. g-1·FW·h-1, GS: µmol·mg-1 protein·h-1

Point 2: In Fig. 3 -Fig. 6, and fig. 8, only the data of K0 and K180 are provided, while data for K60, K120, K240, etc. are not provided. I think all data should appear in the manuscript. If you feel that the data is too large in the diagram, you can submitting it in the form of an attachment. Additionally, there are “(Supplementary Table 1- Supplementary Table 7)” in the manuscript, but Table data not provided in Supplementary.

Response 2: Fig. 3 -Fig. 6, and fig. 8 the data of K₆₀, K₁₂₀ and K₂₄₀ are shown in the Supplementary Table, and I have submitted the Supplementary material.

Point 3: Line 322: the Sentences “SS, JS, BS, FS, and MS are foxtail developmental stages.” is redundant, please delete it.

Response 3: After modification, we have deleted “SS, JS, BS, FS, and MS are foxtail developmental stages”. (Line 297).

Point 4: Line 536-537: and Zhangza 10 is K absorptive ability cultivar with higher K concentration without K application and greater roots. Modify to: and Zhangza 10 is K absorptive ability cultivar with greater roots and higher K concentration without K application.

Response 4: After modification, we have Modify to “and Zhangza 10 is K absorptive ability cultivar with greater roots and higher K concentration without K application”. (Line 496-497).

Reviewer 3 Report

This is a well written paper in excellent English describing experiments carried out in two years with two varieties of foxtail millet to determine the uptake of potassium and nitrogen in plant components and the impact on yield when potassium fertilisers were applied at five different rates. Detailed results are well summarised with effective discussion. The figures are numerous but clear and simple with statistical significance well shown and provided with excellent captions. A few very minor corrections are suggested:

Lines 110-111 - We are told when the seeds were planted and when harvests were made. More details should be given – were seeds broadcast, hand planted in rows, machine sown with a drill, to what depth, at what row spacing and what seeding rate? Whilst these were not experimental variables, they can affect nutrient uptake due to inter-plant competitive effects, and the reader will be interested to know what arrangements were made. Similarly, though the reader is advised in section 2.6 that yield was determined by hand-harvesting subplots, that information could also be foreshadowed at this point of the text.

Line 130 states “Local production standard practices were adopted”. That will mean nothing to the reader – suggest need a short summary of them.

Line 162 – The reference 26 in the reference list contains an error. The year of publication is given as 2016 when it should be 2021, though the rest of the reference is correct. See DOI: 10.1016/j.ecoenv.2021.112195

Line 182 – It is suggested that “…. =(KAV in plants in under K application - …” should be “…-( KAV in plants receiving K application - …”

Line 194-194 - The sentence “The time-course and accumulation rate of dry matter in millet shoots treated with different K fertilizer application rates(Fig 2).” needs a verb.

Line 451 –reads “Specifically, unreasonable soil fertilization reportedly has a significant effect on crop yield,…”. What does “unreasonable” mean?

Please see minor suggestions above

Author Response

Response to Reviewer 3 Comments

Point 1: Lines 110-111 - We are told when the seeds were planted and when harvests were made. More details should be given – were seeds broadcast, hand planted in rows, machine sown with a drill, to what depth, at what row spacing and what seeding rate? Whilst these were not experimental variables, they can affect nutrient uptake due to inter-plant competitive effects, and the reader will be interested to know what arrangements were made. Similarly, though the reader is advised in section 2.6 that yield was determined by hand-harvesting subplots, that information could also be foreshadowed at this point of the text.

Response 1: After modification, we added the relevant details about sowing and harvesting. (Line 116-119 and Line 152). Line 116-119: Experimental units were comprised of square 25-m2 plots. Millet seeds were mechanized sown in drilling about 4 cm deep and 35 cm rows distance. Seedlings were thinned out at three leaf stage to maintain plants distance of 8 cm and 12 cm for Jingu 21and Zhangza 10, respectively.

Point 2: Line 130 states “Local production standard practices were adopted”. That will mean nothing to the reader – suggest need a short summary of them.

Response 2: “Local production standard practices were adopted” means “Weed control was done by hand during millet growing period, without artificial irrigation and pest control.” Therefore, we have deleted this sentence. (Line 119)

Point 3: Line 162 – The reference 26 in the reference list contains an error. The year of publication is given as 2016 when it should be 2021, though the rest of the reference is correct. See DOI: 10.1016/j.ecoenv.2021.112195.

Response 3: We have corrected the year of reference 26. (Line 586-589.

Point 4: Line 182 – It is suggested that “…. = (KAV in plants in under K application - …” should be “…- (KAV in plants receiving K application - …)”

Response 4: According to your suggestion, we modify the formula to “Apparent utilization rate of K fertilizer (AURK, %) = (KAV in plants in receiving K application - KAV in plants receiving no K application) / K application rate×100.” (Line 170-173).

Point 5: Line 194-194 - The sentence “The time-course and accumulation rate of dry matter in millet shoots treated with different K fertilizer application rates (Fig 2).” needs a verb.

Response 5: After modification, this sentence has been modified to “Dry matter accumulation and accumulation rate in millet shoots treated with different K fertilizer application rates show similar dynamics with time-course (Fig. 2).” (Line 182-183).

Point 6: Line 451 –reads “Specifically, unreasonable soil fertilization reportedly has a significant effect on crop yield, …”. What does “unreasonable” mean?

Response 6: “unreasonable” means “under- and over- fertilization”. (Line 418)