Evaluating Overhead Sprinklers and Sprayers for Heatwave Protection in Avocado Orchards
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsOverall, I found the manuscript interesting and well executed. The study tackles a very relevant problem, especially under current climate conditions, and the fact that the experiment was carried out over three consecutive seasons is a clear strength. The dataset is quite complete, combining physiological measurements, temperature monitoring and yield data, which gives a solid basis for the conclusions.
I also think the practical angle of the work is valuable, particularly the focus on low-discharge systems that could realistically be adopted by growers. The figures are generally clear, and some results, especially those related to temperature reduction and fruitlet response, are quite convincing.
That said, there are several points that, in my opinion, need to be clarified or discussed in more depth before the manuscript is ready.
Comment 1. Introduction and framing of the work
The introduction gives a good general overview of heat stress in avocado, but it feels a bit descriptive. It is not entirely clear what is really new in this study compared to previous work by the same group. For example, the manuscript mentions earlier studies using higher discharge rates, but the specific gap this work fills could be explained more clearly. Right now, the novelty is there, but it is somewhat implicit.
Comment 2. Experimental design and representativeness
The experiment is well organized and spans three years, which is a strong point. However, everything is done at a single location and under one set of conditions. This is understandable, but it would help if the authors briefly discussed how transferable these results are to other climates or orchard systems. Also, the activation thresholds for the cooling system (above 36 °C and low humidity) are mentioned in the methods, but it would be useful to comment on how often these conditions actually occur and whether this setup is realistic for growers in other regions .
Comment 3. Interpretation of stem water potential (Figure 1)
The reduction in water stress is clear in Figure 1, where treated trees show higher (less negative) values compared to the control. However, the text simply states the difference without really discussing its physiological meaning. A difference of around 2 MPa is quite large, and it would be helpful to relate this to known thresholds for stress in avocado, or to explain what this implies in terms of tree functioning.
Comment 4. Stomatal conductance (Figure 2)
The increase in stomatal conductance is quite striking. This is an important result, but it is only briefly mentioned. It would be useful to discuss whether this increase is entirely due to improved water status, or also linked to microclimate changes around the canopy. Right now, it feels like a key result that is somewhat underexplained.
Comment 5. Yield results (Figure 3)
The yield increase is one of the most relevant outcomes of the study. However, when looking at the figure, the effect is not consistent across all years. It seems strongest in 2022 and less clear in the following years, and even statistically significant only in one case. This variability should be discussed more openly. At the moment, the text highlights the average increase (around 42%), but does not really address the year-to-year differences shown in the data.
Comment 6. Salt accumulation in leaves (Table 1)
This is a very interesting part of the study, especially the comparison between washed and unwashed leaves. The fact that washing only slightly reduces Na and Cl suggests that salts are actually entering the leaf tissue. However, the discussion remains quite brief. For instance, in 2023 chlorine levels roughly double in treated leaves, which is not a minor effect. Even if thresholds are not exceeded, it would be worth discussing whether repeated exposure over more years could become problematic.
Comment 7. Canopy temperature (Figures 4 and 5)
The thermal images and maps are convincing, and the temperature reduction of about 6-8 °C is consistent across years. This part is well presented. Still, it would help to connect these reductions more directly to physiological responses. For example, linking canopy temperature changes more explicitly with the SWP and stomatal conductance results would make the story more cohesive.
Comment 8. Fruitlet temperature (Figure 6)
This is one of the strongest sections of the paper. The difference between sun-exposed and shaded fruitlets is clearly shown, and the cooling effect is substantial (5-10 °C). One detail that caught my attention is the very high temperatures in the control (around 41 °C in 2023), which are described as potentially harmful. It might be worth briefly discussing how often such extreme values occur in practice and whether they are typical or represent an extreme event.
Comment 9. Relationship between canopy and fruitlet temperature (Figure 7)
The correlation between canopy and fruitlet temperature is interesting, but the discussion is quite short. The differences between years are mentioned but not really explored. Since 2024 behaves slightly differently, it would be good to at least suggest a more concrete explanation, for example, differences in canopy structure or measurement conditions.
Comment 10. Discussion section
The discussion is generally solid, but in some parts it reads more like a continuation of the results rather than a deeper interpretation. For example, the explanation of cooling effects through reduced VPD and improved water status is reasonable, but it would benefit from a bit more critical perspective. Also, the comparison with previous studies is useful, although sometimes it feels more like confirmation than discussion.
Comment 11. Practical implications
The manuscript states that pulse sprinklers may be more cost-effective because one unit can cover several trees. This is an important point, but it is only briefly mentioned. Since the study has a strong applied angle, it would be useful to expand slightly on practical considerations such as installation, maintenance, or potential limitations in commercial orchards.
Comment 12. Writing and clarity
In general, the manuscript is readable, but there are small issues throughout the text: some long sentences, minor grammar issues, repetition. A careful language revision would improve the overall flow.
Final remark:
Overall, the study is solid and the results are convincing, especially from an applied perspective. The main issue is not the experimental work itself, but the depth of the discussion. Strengthening the interpretation and connecting the different results more clearly would significantly improve the manuscript.
Author Response
We are thankful for the reviewer for the positive and valuable revision of our manuscript
Comment 1: Overall, I found the manuscript interesting and well executed. The study tackles a very relevant problem, especially under current climate conditions, and the fact that the experiment was carried out over three consecutive seasons is a clear strength. The dataset is quite complete, combining physiological measurements, temperature monitoring and yield data, which gives a solid basis for the conclusions.
Response 1: Thank you for the positive feedback
Comment 2: I also think the practical angle of the work is valuable, particularly the focus on low-discharge systems that could realistically be adopted by growers. The figures are generally clear, and some results, especially those related to temperature reduction and fruitlet response, are quite convincing.
Response 2: Thank you for the positive feedback
Comment 3: Comment 1. Introduction and framing of the work
The introduction gives a good general overview of heat stress in avocado, but it feels a bit descriptive. It is not entirely clear what is really new in this study compared to previous work by the same group. For example, the manuscript mentions earlier studies using higher discharge rates, but the specific gap this work fills could be explained more clearly. Right now, the novelty is there, but it is somewhat implicit.
Response 3: To address the request, we added a sentence at the end of the introduction " Hence, while the previous study established the general efficacy of evaporative cooling, this research moves from "proof of concept" to commercial viability and physiological precision"
Comment 4: Comment 2. Experimental design and representativeness
The experiment is well organized and spans three years, which is a strong point. However, everything is done at a single location and under one set of conditions. This is understandable, but it would help if the authors briefly discussed how transferable these results are to other climates or orchard systems. Also, the activation thresholds for the cooling system (above 36 °C and low humidity) are mentioned in the methods, but it would be useful to comment on how often these conditions actually occur and whether this setup is realistic for growers in other regions .
Response 4: We added a sentence at the beginning of the Conclusion in which we address the relevance of the findings globally. " Heatwaves damage to avocado are prevalent in many growing areas such as Santa Ana winds in California, Sharav in Israel, Beg winds in South Africa as well as dry and hot wind in Peru and Australia."
Comment 5: Comment 3. Interpretation of stem water potential (Figure 1)
The reduction in water stress is clear in Figure 1, where treated trees show higher (less negative) values compared to the control. However, the text simply states the difference without really discussing its physiological meaning. A difference of around 2 MPa is quite large, and it would be helpful to relate this to known thresholds for stress in avocado, or to explain what this implies in terms of tree functioning.
Response 5: Thank you for this important point; actually by looking on the literature we realized that we has a mistake and preset data in 'bars' as they were in 'MPa'. Hence, the differences between treatment is smaller. This mistake has been corrected and now the values are 1/10 than were presented before. In respect directly to the comment- we added a paragraph in the Discussion which refer to the level of water stress in the experimental trees, as reflected by the literature.
Comment 6: Comment 4. Stomatal conductance (Figure 2)
The increase in stomatal conductance is quite striking. This is an important result, but it is only briefly mentioned. It would be useful to discuss whether this increase is entirely due to improved water status, or also linked to microclimate changes around the canopy. Right now, it feels like a key result that is somewhat underexplained.
Response 6: We added a short paragraph in the discussion to address this comment
Comment 7: Comment 5. Yield results (Figure 3)
The yield increase is one of the most relevant outcomes of the study. However, when looking at the figure, the effect is not consistent across all years. It seems strongest in 2022 and less clear in the following years, and even statistically significant only in one case. This variability should be discussed more openly. At the moment, the text highlights the average increase (around 42%), but does not really address the year-to-year differences shown in the data.
Response 7: We added a paragraph in the discussion to address the possible cause for fluctuation on the cooling system efficacy among years
Comment 8: Comment 6. Salt accumulation in leaves (Table 1)
This is a very interesting part of the study, especially the comparison between washed and unwashed leaves. The fact that washing only slightly reduces Na and Cl suggests that salts are actually entering the leaf tissue. However, the discussion remains quite brief. For instance, in 2023 chlorine levels roughly double in treated leaves, which is not a minor effect. Even if thresholds are not exceeded, it would be worth discussing whether repeated exposure over more years could become problematic.
Response 8: The possible reason for increased accumulation of salts in 2023 is presented in the Results section (section 2.4) and its probably related to the elongated operation time in that year. We added a short paragraph regarding the long-term use of this system on salinity damage to trees ("Still, the effect of salinity would probably be temporal and not continues as happen with irrigation was brackish water when Na accumulates in the trunk along the time (Lazare et al., 2021) This is because of the limited time exposure to salinity and the tendency of leaf expose to salinity to drop down and be replaced by new leaves when using evaporative cooling. ").
Comment 9: Comment 7. Canopy temperature (Figures 4 and 5)
The thermal images and maps are convincing, and the temperature reduction of about 6-8 °C is consistent across years. This part is well presented. Still, it would help to connect these reductions more directly to physiological responses. For example, linking canopy temperature changes more explicitly with the SWP and stomatal conductance results would make the story more cohesive.
Response 9: Thank you for the positive perspective. Its good proposal, however, the fact that thermal imaging and SWP measurements were not conducted simultaneously, at the same time does not allow us to those analysis
Comment 10: Comment 8. Fruitlet temperature (Figure 6)
This is one of the strongest sections of the paper. The difference between sun-exposed and shaded fruitlets is clearly shown, and the cooling effect is substantial (5-10 °C). One detail that caught my attention is the very high temperatures in the control (around 41 °C in 2023), which are described as potentially harmful. It might be worth briefly discussing how often such extreme values occur in practice and whether they are typical or represent an extreme event.
Response 10: We added a paragraph in the Discussion to refer to this point; " Unfortunately, there is almost no literature that followed avocado's young fruitlets temperature under high ambient temperature in avocado and its effect of the developing fruit physiology and quality. However, we might expect increase in sunburn incidence as well as internal damage in the mature fruit."
Comment 11: Comment 9. Relationship between canopy and fruitlet temperature (Figure 7)
The correlation between canopy and fruitlet temperature is interesting, but the discussion is quite short. The differences between years are mentioned but not really explored. Since 2024 behaves slightly differently, it would be good to at least suggest a more concrete explanation, for example, differences in canopy structure or measurement conditions.
Response 11: There is a tentative explanation in the Results section " This difference might be attributed to differences in the meteorological conditions during the day of the campaign, or different canopy structure (volume etc.) during the years."
Comment 12: Comment 10. Discussion section
The discussion is generally solid, but in some parts it reads more like a continuation of the results rather than a deeper interpretation. For example, the explanation of cooling effects through reduced VPD and improved water status is reasonable, but it would benefit from a bit more critical perspective. Also, the comparison with previous studies is useful, although sometimes it feels more like confirmation than discussion.
Response 12: We made substantial changes in the discussion, we hope that it address the reviewer' comment
Comment 13: Comment 11. Practical implications
The manuscript states that pulse sprinklers may be more cost-effective because one unit can cover several trees. This is an important point, but it is only briefly mentioned. Since the study has a strong applied angle, it would be useful to expand slightly on practical considerations such as installation, maintenance, or potential limitations in commercial orchards.
Response 13: We elaborated about the benefit of sprinklers and added the main components of cost saving (installation and maintenance- with less units the cost is much lower)
Comment 14: Comment 12. Writing and clarity
- In general, the manuscript is readable, but there are small issues throughout the text: some long sentences, minor grammar issues, repetition. A careful language revision would improve the overall flow.
Response 14: We re-sent the ms. to a professional scientific editor to improve the language.
Comment 15: Final remark:
Overall, the study is solid and the results are convincing, especially from an applied perspective. The main issue is not the experimental work itself, but the depth of the discussion. Strengthening the interpretation and connecting the different results more clearly would significantly improve the manuscript.
Response 15: We have tried our best to improve it, following the specific comments raised by the reviewer.
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this manuscript, Arnon Dag and colleagues evaluated the effects of operating pulsing sprinklers or sprayers installed above the canopy during spring heatwaves, over three consecutive seasons in a Hass avocado orchard. I have following comments:
1, For the Title, the present version is more suitable for a review rather than a research article. I suggest to employ “Evaluating overhead sprinklers and sprayers for heatwave protection in avocado orchards”.
2, For the keywords, “sprinklers” and “sprayers” appeared in the title should be replaced with other words in the list.
3, For the Figure 1, pictures showing pulsing sprinklers or sprayers installed above the canopy should be exhibited, and images showing avocado growth should be included.
4, For the Figure 2, microscopy images showing stomata should be exhibited.
5, For Figure 3, results of statistical analysis for the 2023 and 2024 groups should be included
6, For Table 1, standard error value should be included.
7, For Figure 4, scale bar should be included, and data for imaging should described in the legend.
8, The Discussion section should be divided into several subsections and each subsection should be properly entitled.
9, For the materials and methods, genotypes of avocado examined in this study should be described. Plant growth conditions like temperature, humidity, light cycle and intensity should be stated. Sampling numbers, biological and technical replicates should be clarified.
Author Response
We are thankful for the reviewers for their positive and valuable revision of our manuscript
Comment 1: In this manuscript, Arnon Dag and colleagues evaluated the effects of operating pulsing sprinklers or sprayers installed above the canopy during spring heatwaves, over three consecutive seasons in a Hass avocado orchard. I have following comments:
1, For the Title, the present version is more suitable for a review rather than a research article. I suggest to employ “Evaluating overhead sprinklers and sprayers for heatwave protection in avocado orchards”.
Response 1: We revised the title in accordance with the suggestion
Comment 2: For the keywords, “sprinklers” and “sprayers” appeared in the title should be replaced with other words in the list.
Response 2: We omitted “sprinklers” and “sprayers" from the list of keyword and added salinity instead
Comment 3: For the Figure 1, pictures showing pulsing sprinklers or sprayers installed above the canopy should be exhibited, and images showing avocado growth should be included.
Response 3: We added pictures of the sprinklers and sprayers installed above the canopy to the figure
Comment 4: For the Figure 2, microscopy images showing stomata should be exhibited.
Response 4: We added a picture of stomates on avocado leaf in Figure 2 as requested.
Comment 5: For Figure 3, results of statistical analysis for the 2023 and 2024 groups should be included
Response 5: There were no significant differences between the treatments in 2023 and 2024, therefore, letters indicating significant differences does not appear (we refer to this in the title ' Different letters indicate significant differences between treatments (p<0.05)'.
Comment 6: For Table 1, standard error value should be included.
Response 6: We added values of standard deviation to the table
Comment 7: For Figure 4, scale bar should be included, and data for imaging should described in the legend.
Response 7: We added a scale in the figure, as was requested
Comment 8: The Discussion section should be divided into several subsections and each subsection should be properly entitled.
Response: We looked on previously published papers in Plants, while in some papers the Discussion is divided to subsections with subtitles, in other papers, this chapter is written in continues format, without subtitle (the format we adopted)
Comment 9: For the materials and methods, genotypes of avocado examined in this study should be described. Plant growth conditions like temperature, humidity, light cycle and intensity should be stated. Sampling numbers, biological and technical replicates should be
Response 9: The genotype that was tested was 'Hass' cultivar- this information appears at the first row at the Materials and Methods. It would be difficult to provide detailed information on temperature, humidity and radiation on the site along the 3 season. However, to address the request, we added a paragraph " The experimental site has a typical Mediterranean climate with hot dry summers and mild winters with annual precipitation averaging ~330 mm falling exclusively from October until April and concentrated over November–March and average relative humidity of 60-65%. ". The information on biological replicates (4) appears at the end of paragraph 4.1. in the Materials and Methods. The numbers of samples appear in this chapter, per each measurement.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsI would like to thank the authors for the careful revision of the manuscript. The new version has improved substantially, particularly in the interpretation of the physiological responses, the discussion of year-to-year variability, and the practical implications of the cooling systems. Most of the previous concerns have been adequately addressed.
Before final acceptance, I only recommend a few minor revisions:
Given the correction related to stem water potential units (bar vs MPa), I recommend carefully checking that all values, units, figure labels, and related interpretations are fully consistent throughout the manuscript.
The discussion is now considerably stronger. However, a final careful language and typographical revision would still be beneficial, as a few minor stylistic inconsistencies remain in the text.
In Figure 7, the explanation for the different behavior observed in 2024 is now mentioned, but it could still be phrased slightly more clearly to emphasize that this interpretation remains tentative.
Overall, the manuscript is now in good condition and suitable for publication after these minor adjustments.
Author Response
Comment 1: I would like to thank the authors for the careful revision of the manuscript. The new version has improved substantially, particularly in the interpretation of the physiological responses, the discussion of year-to-year variability, and the practical implications of the cooling systems. Most of the previous concerns have been adequately addressed.
Response 1: Thank you for the positive feedback
Before final acceptance, I only recommend a few minor revisions:
Comment 2: Given the correction related to stem water potential units (bar vs MPa), I recommend carefully checking that all values, units, figure labels, and related interpretations are fully consistent throughout the manuscript.
Response 2: We carefully verified that all values, units, figure labels, and related interpretations are fully consistent throughout the manuscript.
Comment 3: The discussion is now considerably stronger. However, a final careful language and typographical revision would still be beneficial, as a few minor stylistic inconsistencies remain in the text.
Response 3: Thank you for the positive feedback on the revised discussion we have made additional final careful language and typographical revision with professional Scientific editor
Comment 4: In Figure 7, the explanation for the different behavior observed in 2024 is now mentioned, but it could still be phrased slightly more clearly to emphasize that this interpretation remains tentative.
Response 4: As written, we are not sure about the reason for the slightly different response in 2024, therefore we started the sentence with 'might be attributed'
Comment 5: Overall, the manuscript is now in good condition and suitable for publication after these minor adjustments.
Response 5: Thank you, we have made the minor adjacent, as requested
Reviewer 2 Report
Comments and Suggestions for AuthorsAuthors have addressed each of my previous comments in the revision.
Author Response
Comment 1: Authors have addressed each of my previous comments in the revision.
Response 1: Thank you !
