Development of Multi-Unit Orchard Centrifugal Spray System and Deposition Evaluation on Pear Trees
Luiz Cláudio Garcia
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors- The manuscript would benefit from a detailed schematic of the investigated centrifugal spraying system. I kindly request that the authors provide:
- A dimensioned diagram of the sprayer construction, including nozzle placement, airflow channels, and centrifugal disc geometry.
- A brief explanation of the design rationale: Why were these specific dimensions chosen? Were they based on prior studies, engineering constraints, orchard canopy characteristics, or optimization trials?
Such information is essential for reproducibility and for understanding how the system could be adapted to other orchard configurations.
- The authors should clarify why pear trees were selected as the test crop. Please address the following points:
- Were pear canopies chosen due to their leaf morphology, canopy density, or commercial relevance?
- Do the authors expect that tree species would significantly influence droplet behavior and deposition patterns?
- Which factors—such as leaf surface roughness, canopy porosity, leaf orientation, or growth habit—might cause the results to differ in apples, peaches, cherries, or other orchard crops?
A short discussion on the generalizability of the findings would strengthen the manuscript.
- The manuscript compares deposition performance between hydraulic and centrifugal systems, but it does not address energy consumption, which is a critical practical parameter. Please provide a concise comparative analysis of the two systems, including:
- Power requirements of the hydraulic pump versus the centrifugal mechanism
- Estimated energy consumption per hectare.
- Any trade‑offs between improved deposition and increased (or decreased) energy demand.
- Even approximate or literature‑based values would help readers assess the overall efficiency and economic feasibility of the centrifugal system.
The study is promising and contributes valuable insights into orchard spraying technology. However, the manuscript requires additional technical detail and contextual discussion to ensure clarity, reproducibility, and broader applicability. Addressing the points above will significantly improve the scientific rigor and practical relevance of the work.
Author Response
We are grateful to the reviewers for their insightful comments and constructive suggestions. In response, we have carefully revised the manuscript and prepared a detailed point-by-point response to each comment. Please refer to the attached file for our full responses.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDevelopment of Multi-unit Orchard Centrifugal Spray System and Deposition Evaluation on Pear Trees
Shaoqing Xu, Yanfang Li, Ziqi Geng, Peng Qi, Jianli Song
The paper needs more guidance on “what and why” you decided to use the centrifugal air-assisted spraying method. It isn’t clear in the current incarnation what is gained from this approach vs. the conventional approach of using an air assisted sprayer. In the conclusions section you verbalize about the superiority of the method, but in the current write-up it was hard for me to come to the same conclusion. I believe everything is in order but requires more clarification/revision on what you propose and concluded and why. Thus, I can only recommend publication after major revision (in the grammar) although the paper falls between minor and major revision. A lot of the paper you just report what you did w/o any clarification or insight into what the observations mean. I suggest the authors revise this manuscript, considering all responses from reviewers.
L13. An air assisted-sprayer is a primary tool for pest and …
L21. Need a quick explanation of what the “Foliage Area Volume Densities (FAVD) is”?
L30. Consider adding something along the lines of “We did not include and drift component/insight for the drops being sprayed”.
L40. Please check when hyouhave a citation. Sometimes you have a space but often no space, i.e., … spraying performance[4]. Should this be … spraying performance [4]. Please check all throughout the paper for consistency.
L41. … pesticide deposition is can be insufficient [5].
L45. Note: Consider adding something like “Improved coverage corresponds to less non-target impact for drops not deposited at the leaf surface”.
L47-49. Rewrite to something like “Multi-unit orchard air-assisted sprayers can be considered where precise control of application parameters is needed”.
L50. “The amount of deposition on the … although various types of orchard ... on the market”.
L61. Nanotechnology has also provided … at the microscopic level in recent years.
L65. … have been identified [Ref?].
L68. Why can’t viable products be mass produces? Please add a single sentence response.
L67-68. This sentence is confusing and needs rewritten.
L70-72. Adjustment strategies can be modified … deposition results depending on the application equipment and scenario.
L75. … 40%. Now a new paragraph, beginning with “Droplet size is on of the most …”
L80. …on the abaxial leaf surface but at the expense of off-target movement.
L93-95. Centrifugal nozzles in atomization and pesticide deposition despite the advantages have rarely been implemented … sprayers use integrated centrifugal nozzles into an orchard air-assisted spraying system (CASS).
L99. …system was tested, and for its deposition within the canopy (evaluated under field conditions) with comparisons made against a conventional orchard air-assisted sprayer.
Figure 1 and Figure 2. Font is too small for legibility? Seems border line. Please check journal requirements.
L134. In the research of spray system, The vertical deposition …
L136. … accurately determined, to thereby providing provide critical data for …
Figure 3a. Font size in figure 3A is way to small.
L164. The Pear trees were …
L165. As Trees in this plot were at the … annual pruning such that their Foliage Area …
L168-169. Half of the trees were pruned to reduct the leaf density without … structure.
Figure 5b. I can’t tell what this figure includes. Perhaps enlarging and reducing contrast will help.
L197. … Figure 6, five vertical PVC pipes …
L207. … all fans were started and adjusted to an …
L224. What is the purpose for this? Please explain.
L265. Need a summary section even about this observation and what it means.
Figure 8. Need larger font (see journal requirements).
L271. Data on average leaf area … were obtained through measurement and analysis (Table 2).
L281. … number, and as would be expected FAVD in different …
L283-295. Looks like font size has been decreased from this point forward.
L289-292. Give a reason why you think this occurred? (ditto for L294-295).
Figure 9. Font size needs enlarged for visibility.
L302-327. This section needs to be corrected and expanded upon for clarity.
L301. Is it possible to show a photograph what is the adaxial vs ab. Coveratin is? Note clear from figure what you are describing. Please add more sentences about diff. outlet velocities.
L327. “proximal” and ‘distal”, it would be nice if you provide a figure for what these are.
Figure 10. Font size needs increased. Also, I’ve never seen graphics like this before, so please outline/summarize what these graphics represent in words so unfamiliar readers can follow
L348. Would be nice if you give a 2 sentence summary of what this meases (at least conceptually).
Figure 11. Font size needs increased per Journal requirements. You also need to explain what the different significance levers are and what Figure a) and b) represent and why they are different? I see you have it figure caption but should be in the text also when explaining this figure.
L363-364. Nice if you can explain this observation, but this is you results section.
Figure 12 b) and c). Font size minimum? And just like figure 10, you need to explain what these graphics represent and/or are measuring.
Figure 13. x-axis font it to small to be legible.
L411. Need to specify what the distance is, i.e., “As the distance increased, …”
L414. … with droplet motion at this height becoming dominated by gravity.
L424. Isn’t this the same pattern seen by conventional systems?
L450-451. This just may be a phenonoma due to flujid flow characteristics, which will also make for more explained off-target droplet drift?
L455. Perhaps some simple computational fluid dynamics (CFD) simulations for drop interactions with the canopy could show this?
L472. … centrifugal nozzles may hold significant … efficient agriculture (due to its constant drop size?)
L477. This study integrates centrifugal nozzles into an centrifugal air-assisted spray system.
L482. “superior” ??? need more discussion throughout this paper on both methods such that the reader can be swayed to this conclusion. In the paper’s current incarnation, I was not. So asking what is meant by “superior”. Need a sentence or two to explain (with data to verify this claim). Also I think you need to offer more explanations in the results section about the difference between hydraulic and centrifugal systems that you claim here. I don’t remember reading much about this throught this paper, so this statement needs to be bolstered.
L487. Consider adding “However, the smaller drops generated by the centrifugal system raises questions about increased off-target droplet movement via wind currents”.
Comments for author File: Comments.pdf
Author Response
We are grateful to the reviewers for their insightful comments and constructive suggestions. In response, we have carefully revised the manuscript and prepared a detailed point-by-point response to each comment. Please refer to the attached file for our full responses.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsTITLE
✓ No suggestions for improvement.
ABSTRACT
✓ I recommend describing the objective, experimental design, variables analyzed, and main conclusion.
KEYWORDS
✓ Avoid repeating words already included in the title.
INTRODUCTION
✓ It is recommended to enrich the Introduction with similar studies to provide stronger support for the discussion of the results.
MATERIALS AND METHODS
✓ The titles of tables and figures should be self-explanatory. For example: Table 1. Yield components of wheat (Triticum aestivum), cultivar Texas™, influenced by fungicide applications with and without adjuvants, 2025 growing season, Farm Sacramento (California, USA).
✓ Was an experimental design with replications adopted?
✓ Why were only very fine droplets evaluated?
✓ Has the droplet collection method been scientifically validated?
✓ It is recommended to use kPa as the pressure unit.
✓ Is the calculation of nozzle pressure and flow rate correct? Should it not be 0.45 L min⁻¹?
✓ It is recommended to evaluate five air-speed levels to enable polynomial regression analysis.
RESULTS AND DISCUSSION
✓ Do electrically uncharged droplets not follow curved trajectories to reach the abaxial leaf surface? Could deposition have occurred as a result of the airflow? I suggest discussing these mechanisms in greater detail.
✓ The coverage percentage was high for very fine droplets, which generally have limited mass available for deposition. I suggest discussing the possible reasons for this result in greater depth.
✓ Compare the results with those reported in similar studies previously published on this topic.
✓ Ideally, several droplet sizes should be tested for disease control using contact fungicides. This would allow the identification of possible significant differences among treatments.
CONCLUSION
✓ No suggestions for improvement.
REFERENCES
✓ I recommend verifying that the References comply with the journal guidelines and ensuring that all in-text citations are included in the reference list and vice versa.
I recommend testing both conventional and modified machines for disease control, evaluating their effectiveness as well as their economic viability.
Author Response
We are grateful to the reviewers for their insightful comments and constructive suggestions. In response, we have carefully revised the manuscript and prepared a detailed point-by-point response to each comment. Please refer to the attached file for our full responses.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsOnly recommendation is in Fig 12 caption. where the authors mention warm and cool colors. If I didn't know what warm or cool colors were, it would be difficult in interpreting this figure.
Much easier to follow the newly revised manuscript IMHO. Thank you autorhos for heeding recommendations.to improve the article.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have addressed the issues raised by the reviewer. I recommend publication.
