Application of Ethephon Manually or via Drone Enforces Bud Dormancy and Enhances Flowering Response to Chilling in Litchi (Litchi chinensis Sonn.)
, Huicong Wang 1 and Xuming Huang 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Editors and Authors,
I read with interest the manuscript entitled “Foliar application of ethephon impedes photosynthesis temporarily, enforces bud dormancy and enhances flowering response to chilling in litchi (Litchi chinensis Sonn.)”. The study aimed to find out the optimal dosage for the application of ethephon that may balance between flush control and floral promotion effect and the detrimental effect on leaves and to evaluate the feasibility of drone application of ethephon for flush control. Therefore, the manuscript needs some adjustments so that it can then be forwarded to the publication process. The manuscript has the potential for publication in the journal Horticulturae and needs the following adjustments:
TITLE
- Replace “foliar application” with “exogenous application”.
ABSTRACT
- The objective should be reduced. It is unnecessary to inform you that we are trying to discover the ideal dose and see the possibility of replacing manual spraying with a drone. The objective must be clear and direct. Review.
- Information about the treatments used was missing. What was tested?
- Add information about the variables analyzed. The objective is described, and the main results are mentioned. Insert more information about the Material and Methods section.
- Replace the words and keywords that are repeated in the title. This will improve the search for the article after publication.
INTRODUCTION
- Insert a paragraph about the species (lychee), highlighting information about the importance of the species, among other information. The first paragraph talks about the flowering of the species and the effect of temperature on the plant organs.
- Divide the paragraphs. There is a lot of information, and the paragraph is very long.
Are there other studies with lychees testing the treatments used in this study? If there are any with other species, they can be added here to enrich this section.
- Insert some hypotheses to enrich the research.
- The objectives should be similar to those presented in the Abstract. Review.
MATERIAL AND METHODS
- 2. “Material” and Methods
- 2.1. “Material”. Material of what? The title is incorrect. The correct term would be “study area”.
- Was only the temperature data collected? And the data relative humidity?
- Why was 15°C used as the up-line temperature? Are there any previous studies confirming this?
- How many ethephon applications were made? What time were these applications made?
- Which methodology was used to measure the leaf fall rate? Please quote.
- Was only the net photosynthesis rate measured? And what about stomatal conductance, transpiration and internal CO2 concentration? Were they not measured?
- Why was the drone not used to apply the other ethephon concentrations??
RESULTS AND DISCUSSION
- Remove the lines inside the figures. Leave a white background.
- In subtopic 3.1.2. It is unnecessary to report that there were no significant differences between the ethephon concentrations. Observe whether this occurred for the other variables and remove it. Leave only the information when there is significance.
CONCLUSION
- Avoid using assumptions. Use direct information. Does ethephon accelerate the seasonal abscission of old leaves in winter and cause suppression of photosynthesis?
- The term “may” is used several times. This should be removed.
In the end, it is mentioned that larger solutions of Ethephon should be tested. Why did they say this?
Author Response
Comment 1: Replace “foliar application” with “exogenous application”.
Response1: Reviewer 2 has different suggestion regarding title revision. In response to suggestions from both reviewers, I revised the paper title as “Application of ethephon manually or by drone enforces bud dormancy and enhances flowering response to chilling in litchi (Litchi chinensis Sonn.)”.
Comment 2: The objective should be reduced. It is unnecessary to inform you that we are trying to discover the ideal dose and see the possibility of replacing manual spraying with a drone. The objective must be clear and direct.
Response 2: We have made our objective clear by a sentence “This study aimed to find out the optimal ethephon dosage and to test more efficient way of ethephon application with drone for flush control and flowering promotion in litchi.”
Comments 3: Information about the treatments used was missing. What was tested?
Response 3: OK. We have specified our treatments in abstract (Full-tree spray of 250, 500 or 1000 mg/L ethephon in the season of 2021-2022, and drone spray of 1000 mg/L ethephon in the season of 2022-2023). The tested items included bud growth, leaf drop, photosynthesis, LcFT1 expression and floral induction.
Comments 4: Add information about the variables analyzed. The objective is described, and the main results are mentioned. Insert more information about the Material and Methods section.
Response 4: OK. We have added variables were analyzed, i.e. bud break rate, leaf drop rate, net photosynthetic rate, LcFT1 expression and floral induction (panicle emergence rate and panicle number).
Comments 5: Replace the words and keywords that are repeated in the title. This will improve the search for the article after publication.
Response 5: OK. The keywords are now: Ethylene, LcFT1, flush growth, panicle emergence, leaf drop, photosynthesis
Comment 6: In introduction, insert a paragraph about the species (lychee), highlighting information about the importance of the species, among other information. The first paragraph talks about the flowering of the species and the effect of temperature on the plant organs.
Response 6: OK. We have added a statement “Litchi (Litchi chinensis Sonn.) is one of the most economically important fruit crops in China and is widely cultivated in warm subtropical regions across the world.”.
Comments 7: Divide the paragraphs. There is a lot of information, and the paragraph is very long.
Responses 7: OK. The long paragraph is divided into four paragraphs.
Comment 8: Are there other studies with lychees testing the treatments used in this study? If there are any with other species, they can be added here to enrich this section.
Response 8：We have added 3 references showing effect of ethephon treatment on flowering in apple and sweet cherry.
Comments 9: Insert some hypotheses to enrich the research.The objectives should be similar to those presented in the Abstract.
Response 9: Hypothesis is added and objective of the study is clarified as abstract mentioned.
Comments 10: 2.1. “Material”. Material of what? The title is incorrect. The correct term would be “study area”.
Response 10: We have revised the subtitle as “Site and plant materials for the study”
Comments 11: Was only the temperature data collected? And the data relative humidity?
Response 11: We displayed only air temperature data in the paper. The meteorological station did collect humidity data. Since litchi only responds to chilling temperature for flowering, we only analyze temperature data. Humidity is not involved in flower induction in litchi. Therefore, we did not bother to analyze humidity data.
Comment 12: Why was 15°C used as the up-line temperature? Are there any previous studies confirming this?
Response 12: We have added more explanation why we used 15°C for calculating chilling hours. Cronje et al. (2022) calculated cumulative chilling hours of below 20oC for ‘Mauritius’, which is a relatively low chilling requiring cultivar. ‘Jingganghongnuo’ used in this study is a late cultivar with higher chilling requirement for flowering. Studies by Chen (2002) showed that flowering of ‘Nuomici’, another late litchi cultivar, is secured under temperatures below 15oC. Therefore, we took 15oC as the up-line temperature for calculating cumulative chilling hours for flowering of ‘Jingganghongnuo’.
Comments 13: How many ethephon applications were made? What time were these applications made?
Response 13: In all ethephon treatments, there was a single application. No repeated treatments were made.
Comments 14: Which methodology was used to measure the leaf fall rate? Please quote.
Response 14: By simply counting leaf numbers on 10 tagged shoots in each tree. Please in find in the paragraph “Ten shoots were selected from different directions of the canopy in each tree and tagged. The mumber of compound leaves in each tagged shoot was recorded prior to and after ethephon treatment at weekly intervals, and the number of dropped leaves from the shoots and thus leaf drop rate could be calculated.”
Comment 15: Was only the net photosynthesis rate measured? And what about stomatal conductance, transpiration and internal CO2 concentration? Were they not measured?
Response 15: We used CIRAS-2 for the analysis. The instrument collects numerous data which include net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (E) and internal CO2 (Ci) concentration. However, during our measurement, odd values of stomatal conductance, 9999, occurred occasionally, suggesting moisture sensor did not work stably in the system. Therefore, we have to give up the data of parameters (gs, E and Ci) based on moisture measurement. Only net photosynthetic rate was displayed in the study.
Comment 16: Why was the drone not used to apply the other ethephon concentrations?
Response 16: Because we found 1000 mg/L ethephon showed strong effect in dormancy enforcing by manual spray in 2021-2022 season, this concentration was thus used for drone spray test. We will carry out another study to evaluate more concentrations for drone spray and refine operation parameters such as flying speed, flying height, droplet size, etc.
Comment 17: Remove the lines inside the figures. Leave a white background.
Response 17: OK. The lines inside the figures have been deleted.
Comment 18: In subtopic 3.1.2. It is unnecessary to report that there were no significant differences between the ethephon concentrations. Observe whether this occurred for the other variables and remove it. Leave only the information when there is significance.
Response 18: We insist mentioning some cases where treatments with no difference, which may show important information. For example, Pn in at 5 ad 12 days after treatment (DAT) were significantly reduced by ethephon treatments, but At 19 and 29 DAT, there was no significant difference in Pn among the control and the treatments. This result shows that ethephon caused temporary reduction in Pn, which was recovered within two weeks.
Comment 19: In CONCLUSION, avoid using assumptions. Use direct information.The term “may” is used several times.
Response 19: OK.
Comment 20: Does ethephon accelerate the seasonal abscission of old leaves in winter and cause suppression of photosynthesis?
Response 20: Our study clearly showed that ethephon accelerated (advanced) seasonal abscission of old leaves in winter and caused suppression in photosynthesis in newly mature leaves. The suppression effect on photosynthesis was shown to be temporary.
Comments 21: In the end, it is mentioned that larger solutions of Ethephon should be tested. Why did they say this?
Response 21: We leave this statement in discussion and delete it in the conclusion. Drone spray of ethephon at 1000 mg/L did not fully suppressed bud break like manual spray of ethephon at the same concentration did. Therefore, a test of drone spray of a stronger concentration is needed.
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Editor,
I have reviewed the manuscript titled "Foliar application of ethephon impedes photosynthesis temporarily, enforces bud dormancy and enhances flowering response to chilling in litchi (Litchi chinensis Sonn.)", submitted for possible publication in Horticulturae. Below, I provide my general and specific comments, which I hope will contribute to improving the quality of the submitted work. The topic of the study is relevant within the field of horticulture, particularly given the increasing interest in agricultural practices that enhance flowering and fruit production in economically important species like litchi. The focus on using ethephon as a regulator of photosynthesis and chilling response is novel and valuable. However, the authors should more deeply contextualize their findings within previous research, emphasizing the potential commercial applications or agronomic implications of their results.
Comment to authors
1. The title should reflect the objective stated in the summary section, i.e. manual and drone foliar application. Please adapt it to represent the content of the work.
2. Include in the introduction section the Ethephon molecule, as well as a brief image of how it participates in the leaves to induce flowering.
3. Include a reagents subsection in the materials and methods section.
4. In the materials and methods section, an image can be included that represents the design of how the experiment was carried out, that is, the four ethephon concentration treatments, in the two seasons and two types of foliar application.
5. Include a discussion section that talks about the contribution to sustainability that was generated from this research.
6. I highly recommend further discussion of results. Review: (2022). Journal of Nanomaterials, 2022(1), 5697803: (2023). ACS omega, 8(45), 42319-42328;
Author Response
Comment 1: The title should reflect the objective stated in the summary section, i.e. manual and drone foliar application. Please adapt it to represent the content of the work.
Response 1: The title has been revised as“Application of ethephon manually or by drone enforces bud dormancy and enhances flowering response to chilling in litchi (Litchi chinensis Sonn.)”.
Comment 2: Include in the introduction section the Ethephon molecule, as well as a brief image of how it participates in the leaves to induce flowering.
Response 2: Ethephon is a well-known plant growth regulator with numerous reports about its usage in crop management. We do not think it is necessary to spend text introducing the basic knowledge about its molecule characters. However, we annotated its structural name- 2-chloroethylphosphonic acid in quotation when it was first mentioned in the text and abstract. How foliar application of ethephon induces flowering is not well understood. We can not draw a image of how it participates in the leaves to induce flowering. Foliar spray of ethephon enabled exposure of both the leaves and the terminal buds to ethephon.
Comments 3: Include a reagents subsection in the materials and methods section.
Response 3: This section is not compulsory. Most papers published in Horticulturae including our two previously published papers did not have this section. Therefore, we prefer not including this section.
Comment 4: In the materials and methods section, an image can be included that represents the design of how the experiment was carried out, that is, the four ethephon concentration treatments, in the two seasons and two types of foliar application.
Response 4: The layout of our experiment is clearly describe in the text. We do not think it is necessary to add such an image. We try to minimize the numbers of figures and tables in a paper, avoiding using figures when words can make it clear.
Comment 5: Include a discussion section that talks about the contribution to sustainability that was generated from this research.
Response 5: Please forgive us for not fully understanding you. Sustainability of what? Do you mean long-term effect of ethephon? To improve efficiency of flush control and to avoid massive leaf drop, we tested the effect of a single spray of ethephon solutions not repeated spray. The results showed that a single manual spray of 1000 mg/L ethephon induced a 6-week bud dormancy period without significant leaf drop. In this sense, use of ethephon is a sustainable way for flush control.
Comment 6: I highly recommend further discussion of results. Review: (2022). Journal of Nanomaterials, 2022(1), 5697803: (2023). ACS omega, 8(45), 42319-42328.
Response 6: We searched these publications and found that they are about controlled and prolonged release of nitrogen fertilizers, which are not related with the topic of our study. At current stage, we have no idea about technology regarding controlled and prolonged release of ethephon after application. Therefore, we prefer not to step into it. Anyway, thank you for the suggestion.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe article has been corrected, according to previous suggestions. I recommend publishing it.
Reviewer 2 Report
Comments and Suggestions for AuthorsAccept in present form
