Monitoring Fertilizer Effects in Hardy Kiwi Using UAV-Based Multispectral Chlorophyll Estimation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

(1) It is recommended to supplement the technical parameters of multispectral cameras and hyperspectral cameras in Section 2.2 (such as number of bands, data volume, cost), and explain the specific reasons for choosing multispectral cameras (such as the adaptability of small-scale farmland in South Korea).
(2) It is recommended to supplement detailed descriptions of drone flight parameters in Section 2.2, such as flight altitude, speed, etc., which have an important impact on image quality and resolution.
(3) It is recommended to supplement the measurement parameters of the portable chlorophyll meter in Section 2.3, such as the specific location of the measurement, the blade selection criteria, etc.
(4) Supplement the direct correlation data of NDVI, CCCI, and nitrogen content in Section 3.3 (such as the relationship between SPAD and nitrogen content r=0.7 in the cited literature), and discuss the uncertainty of the model predicting nitrogen content.
(5) The quality of the chart needs to be improved, including the clarity of the chart, the completeness and accuracy of the label, etc., so as to facilitate readers ' better understanding of the research results（such as Fig. 3）.
(6) Check the grammar and spelling errors in the full text to ensure that the language expression of the article is accurate.

Comments on the Quality of English Language

The manuscript possesses the basic framework of an academic paper and accurately presents professional content, but its English language quality requires systematic polishing. It is recommended that the authors use grammar-checking tools (such as Grammarly) to correct spelling and tense errors.

Author Response

Hello.
Thank you for reading my lackluster paper.
I am honored to receive your valuable comments and the opportunity to make corrections.
Please see the attached file.
Thank you.

Best regards,
Sangyoon Lee

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. Introduction contains repetitive content on nitrogen and chlorophyll, instead of focusing on the specific research gap in hardy kiwi monitoring.
2. There is no discussion of environmental or operational constraints like UAV flight conditions, weather variation, or canopy shading that could impact image quality.
3. Lack details on image calibration, lighting correction, and atmospheric adjustments, which are critical for accurate multispectral data interpretation.
4. In Section 3.4, the regression models are only evaluated using R² and RMSE, without including confidence intervals or residual analysis, making the validation incomplete.
5. In Section 3.2 and 5, the study assumes nitrogen levels based on chlorophyll content without directly measuring nitrogen, which weakens the core conclusion.

 

Author Response

Hello.
Thank you for reading my lackluster paper.
I am honored to receive your valuable comments and the opportunity to make corrections.
Please see the attached file.
Thank you.

Best regards,
Sangyoon Lee

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this study, the authors have estimated chlorophyll in plants using several remote sensing indices. The major concern of this study is its lack of novelty. A paper published in Computers and Electronics in 2021 with no. 106292 is very similar to this work. They were working on peanut leaves, and in this work, the authors worked on Hardy kiwi plants. This does not count as novelty. The modeling techniques and regression models are very similar in both works. I also found several papers similar to the method used in this work on other types of plants.

Moreover, the discussion part of the manuscript is very weak. At last, a table should be added to the paper comparing the existing regression models with the results of this work.

Many of the references in this work are old. Recent references published no more than 5 years should be added as we see many improvements in this field in the last five years.

Author Response

Hello.
Thank you for reading my lackluster paper.
I am honored to receive your valuable comments and the opportunity to make corrections.
Please see the attached file.
Thank you.

Best regards,
Sangyoon Lee

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Good improvement in the paper, here are the few suggestions to improve further better

1. The introduction still lacks a clearly stated, crop-specific research gap. Clarify why hardy kiwi requires this UAV-based approach.

2. The correlation between nitrogen and CCCI is modest (r = 0.66). Avoid overstating its reliability as a nitrogen proxy.

3. All models are trained and tested on the same dataset. Acknowledge the need for external validation to assess generalizability.

4. Discuss possible UAV data limitations such as wind, canopy occlusion, or GPS errors and their impact on index accuracy.

5. Add a brief note on the potential saturation of CCCI in dense canopies and mention alternatives that could be tested in future work.

Comments on the Quality of English Language

I recommend a thorough English language edit to improve clarity, flow, and consistency throughout the manuscript.

Author Response

Dear Reviewer,

 Thank you very much for your valuable time and thoughtful review. Your constructive feedback has helped to further improve the quality of this manuscript. All the points you raised have been addressed and revised in the updated version. I look forward to your continued guidance.
 Please check the attached file.

Best regards,
Sangyoon Lee.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Although the authors have tried to improve the work, there are still major concerns about the novelty of this work. As I mentioned earlier, at least the style and method of analyzing the data and the presentation of results section should be improved to differentiate it from previous studies.  Moreover, the Discussion section seems like an Introduction section. No in-depth comparison is provided in this section.

Author Response

Dear Reviewer,

 Thank you very much for your valuable time and thoughtful review. Your constructive feedback has helped to further improve the quality of this manuscript. All the points you raised have been addressed and revised in the updated version. I look forward to your continued guidance.
 Please check the attached file.

Best regards,
Sangyoon Lee.

Author Response File: Author Response.docx