An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Comments posted in the text of the manuscript

Comments for author File: Comments.pdf

Author Response

Responses to reviewer 1. Horticulturae-3149488 R2

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

Comments and Suggestions for Authors

182-184 lines: What is the point of this sentence?

Response: Thank you for pointing this out. We agree with this comment. We improved the sentence that can be found in lines 225-228 in the revised manuscript.

Line 201 - 205. After this excerpt from the text he question arises, do vertical farms use only artificial light or either sunlight or artificial light?

Response: Thank you for pointing this out. We agree with this comment. Therefore we added some statement and explanation. We have also analysed some experimental results on what illumination sources are used in vertical farm (now lines: 248-264).

248 line: Does this part of the sentence refer to vertical farms only in Sweden, or to vertical farms in general?

Response: Thank you for pointing this out. This part refers to vertical farm in Sweden. We have modified the sentence. (line: 306)

345 line: Under what conditions were the control lettuce grown?

Response: Thank you for pointing this out. We correct the  sentence: “control that carried out in a glasshouse where the plants where grown under monitored conditions and natural light with an average PPDF 65 µmol s-1 m-2 [105]” (now lines:404-406).

361-371 Lines. The subsection is about lettuce, and this paragraph begins with a big introduction about arugula. I would suggest citing the data from the study with lettuce first, and then some analogies with arugula, for example, at the end of the paragraph.

Response: Thank you for pointing this out. We agree with this suggestion and we have moved at the end of the section (now lines: 494-504).

408 Line: How to understand keeping". Whether it is about cultivation or something else"

Response: Thank you for pointing this out. We agree with this comment. It means growing and we corrected the sentence (line: 459).

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I reviewed the revised version of the previously submitted manuscript. While the authors have made revisions, there are still issues that need to be addressed before publication.

1.   The title of the manuscript can still be improved. I recommend the following: "An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System."

2.     The authors should clearly state the problems with existing works and differentiate the current study from other related studies, as several review articles have already been published on this topic. A comprehensive analysis of the gaps in existing methods and the necessity of this research should be presented. The novelty of the study should be emphasized, and the topic should be explored in greater depth, which is still lacking in the revised version.

3.     I did not find any detailed discussion summarizing the structure of the paper. I suggest adding a paragraph that outlines the content of each section, such as: "Section 2 discusses [xyz], Section 3 addresses [xyz], etc." The authors mentioned that they added a paragraph summarizing the paper's structure as a section (lines 66-73).

4.     The information presented in Section 2.2 ("Soilless Growing Systems with an Emphasis on Hydroponics") is too simplistic and can be found in various online blogs. Rather than focusing on these basic concepts, the authors should discuss the key challenges associated with these methods. The justification for adopting artificial lighting in these systems should be provided with strong evidence.

5.     The authors should include a new section discussing the future prospects and major challenges of using artificial LEDs for vegetable production in indoor vertical farming systems. This should highlight areas for future research. In the conclusion, the authors stated, "In the future, studies should be carried out on the needs and responses of the varieties at the developmental stages to ensure cost-effective vertical lettuce production in vertical farm systems." However, this is insufficient; as a literature review has been conducted, the key issues should be discussed in greater depth.

Comments on the Quality of English Language

N/A

Author Response

Responses to review report 2-Horticulturae-3149488-R2

Thank you very much for taking the time to review the revised manuscript. We agree with your comments and suggestions which we will respond to in detail below and the corresponding revisions in highlighted in the re-submitted files.

Comments and Suggestions for Authors

I reviewed the revised version of the previously submitted manuscript. While the authors have made revisions, there are still issues that need to be addressed before publication.

1. The title of the manuscript can still be improved. I recommend the following: "An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System."

Response: Thank you for pointing this out. We agree with this suggestion. Therefore, we have change the title of the manuscript to “An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System."

2. The authors should clearly state the problems with existing works and differentiate the current study from other related studies, as several review articles have already been published on this topic. A comprehensive analysis of the gaps in existing methods and the necessity of this research should be presented. The novelty of the study should be emphasized, and the topic should be explored in greater depth, which is still lacking in the revised version.

Response: Thank you for pointing this out. We agree with this comment. Therefore, we added some statement into introduction (now lines 68-91).

3. I did not find any detailed discussion summarizing the structure of the paper. I suggest adding a paragraph that outlines the content of each section, such as: "Section 2 discusses [xyz], Section 3 addresses [xyz], etc." The authors mentioned that they added a paragraph summarizing the paper's structure as a section (lines 66-73).

Response: Thank you for pointing this out. We agree with this suggestion. Therefore, we have added a summary paragraph highlighting the key findings from the chapters which precedes the chapter on Conclusions and Future Perspectives (now lines 548-559.

4. The information presented in Section 2.2 ("Soilless Growing Systems with an Emphasis on Hydroponics") is too simplistic and can be found in various online blogs. Rather than focusing on these basic concepts, the authors should discuss the key challenges associated with these methods. The justification for adopting artificial lighting in these systems should be provided with strong evidence.

Response: Thank you for pointing this out. We agree with this comment. Therefore, we have added some statement regarding the main challenges of soilless growing systems (lines 159-163; 190-199; 203-208; and 211-213).

5. The authors should include a new section discussing the future prospects and major challenges of using artificial LEDs for vegetable production in indoor vertical farming systems. This should highlight areas for future research. In the conclusion, the authors stated, "In the future, studies should be carried out on the needs and responses of the varieties at the developmental stages to ensure cost-effective vertical lettuce production in vertical farm systems." However, this is insufficient; as a literature review has been conducted, the key issues should be discussed in greater depth.

Response: Thank you for pointing this out. We agree with this suggestion. We have supplemented the conclusion, changed the title and highlighted the further potential for research into vertical farming (now lines 576-582).

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I have reviewed the revised manuscript and acknowledge that the authors have addressed the previous suggestions, leading to an overall improvement in the manuscript's quality compared to the first two versions. However, I still have concerns that must be addressed before considering this manuscript for potential publication. My suggestions aim to further enhance the manuscript's quality, particularly by clarifying and strengthening the problem statement.

The problem statement remains underdeveloped, which is critical as it drives the discussion on the use of artificial lighting for sustainable lettuce and microgreens production in an indoor vertical farming system. I recommend incorporating and citing recent studies that highlight the challenges associated with artificial lighting in indoor farming environments.

Between Lines 68 and 92, the authors have added new information, but some of it appears to be region-specific. Given that the use of artificial lighting in indoor farming is a global practice, the manuscript should reflect this broader applicability. Although the manuscript touches on important issues, it is not yet sufficiently prepared or summarized to be recommended for publication in its current form.

The authors have attempted two main tasks: first, providing an overview of soilless farming (including its various types) and vertical farming; and second, discussing the use of LEDs for indoor farming. However, the content from Lines 152 to 242 is too general, with much of it already covered in existing literature. The manuscript should focus more on the key issues related to the use of artificial lighting for sustainable lettuce and microgreens production in an indoor vertical farming system. I suggest presenting the findings of previously published studies more thoroughly, possibly using discussing and tables to illustrate data such as study objectives, LED types, light intensities, soilless farming methods, and study outcomes.

Additionally, please remove keywords that are redundant with the title.

Specific comments:

• Line 39: "Soilless agriculture can address the growing issue of food scarcity, particularly in urban areas." This statement requires justification or an appropriate citation.
• Line 40: "A proposed new method"—please clarify which method is being referred to.
• Line 68: "Previous research has investigated"—it would be beneficial to highlight some specific studies here.
• Line 79: The sentence beginning with "In our future experiment, one of our goals..." seems irrelevant to the current study and should be reconsidered.

Lastly, the manuscript lacks a detailed discussion summarizing the structure of the paper. This should be included at the end of the introduction. I recommend adding a paragraph that outlines the content of each section. For example, "Section 2 discusses [xyz], Section 3 addresses [xyz]," etc. This will help readers better understand the manuscript's organization and the authors' contributions.

Author Response

Review report 2_Horticulturae-3149488 R2

Dear Reviewer,

Thank you very much for taking the time to review the revised manuscript. We especially thank you for your suggestions, which helped us to improve the quality of the manuscript. Taking into account the suggestions, we have revised the introduction chapter, improved section 2 and added a summary table. Below we respond to the comments in detail and have corrected the manuscript highlighting the corrections in the re-submitted file.

Comments and Suggestions for Authors

I have reviewed the revised manuscript and acknowledge that the authors have addressed the previous suggestions, leading to an overall improvement in the manuscript's quality compared to the first two versions. However, I still have concerns that must be addressed before considering this manuscript for potential publication. My suggestions aim to further enhance the manuscript's quality, particularly by clarifying and strengthening the problem statement.

The problem statement remains underdeveloped, which is critical as it drives the discussion on the use of artificial lighting for sustainable lettuce and microgreens production in an indoor vertical farming system. I recommend incorporating and citing recent studies that highlight the challenges associated with artificial lighting in indoor farming environments.

Response: Thank you for pointing this out. We agree with this suggestion and we have added some experience with artificial lighting that can be used for indoor cultivation (now line: 98-120, 115-120).

 

Between Lines 68 and 92, the authors have added new information, but some of it appears to be region-specific. Given that the use of artificial lighting in indoor farming is a global practice, the manuscript should reflect this broader applicability. Although the manuscript touches on important issues, it is not yet sufficiently prepared or summarized to be recommended for publication in its current form.

Response: Thank you for pointing this out. We agree with this comment. The introduction chapter has been revised, global aspects have been added (now lines: 38-60, 98-120).

 

The authors have attempted two main tasks: first, providing an overview of soilless farming (including its various types) and vertical farming; and second, discussing the use of LEDs for indoor farming. However, the content from Lines 152 to 242 is too general, with much of it already covered in existing literature. The manuscript should focus more on the key issues related to the use of artificial lighting for sustainable lettuce and microgreens production in an indoor vertical farming system. I suggest presenting the findings of previously published studies more thoroughly, possibly using discussing and tables to illustrate data such as study objectives, LED types, light intensities, soilless farming methods, and study outcomes.

Response: Thank you for pointing this out. We agree with this comment, so we have changed the structure of chapter 2, first the soilless systems (subchapter 2.1), then the vertical farm (subchapter 2.2, lines. 239-289) has been revised and discussed (lines: 196-203, 207-209).

Thank you for your suggestion. We have also included a summary table showing how the choice of lighting composition gives results in lettuce vertical farm production (Table 1).

Additionally, please remove keywords that are redundant with the title.

Response: Thank you for pointing this out. We agree with this suggestion. Therefore, we removed the hydroponics and added microgreens to the keywords

Specific comments:

Line 39: "Soilless agriculture can address the growing issue of food scarcity, particularly in urban areas." This statement requires justification or an appropriate citation.

Response: Thank you for pointing this out. We agree this comment, therefore we have improved the sentence (now line: 67-71).

Line 40: "A proposed new method"—please clarify which method is being referred to.

Response: Thank you for pointing this out. We agree this comment, therefore we modified the sentence (now Lines 76-78).

Line 68: "Previous research has investigated"—it would be beneficial to highlight some specific studies here.

Response: Thank you for pointing this out. We agree with this suggestion and we modified the sentence and highlighted some studies concerning on the use of LEDs in lettuce and microgreens production in vertical farming system (now line: 98-120, 115-120)

Line 79: The sentence beginning with "In our future experiment, one of our goals..." seems irrelevant to the current study and should be reconsidered.

Response: Thank you for pointing this out. We agree with this comment. Therefore we have deleted those sentences, but have highlighted the use of vertical farming as an option to complement conventional farming (lines: 141-149).

Lastly, the manuscript lacks a detailed discussion summarizing the structure of the paper. This should be included at the end of the introduction. I recommend adding a paragraph that outlines the content of each section. For example, "Section 2 discusses [xyz], Section 3 addresses [xyz]," etc. This will help readers better understand the manuscript's organization and the authors' contributions.

Response: Thank you for pointing this out. We agree with this suggestion and we have included a paragraph you suggested at the end of introduction (now line: 126-139).

 

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I received the revised version of the manuscript entitled: An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System for possible publication in Horticulturae. The authors have revised manuscript and it can be considered for possible publication. Some minor corrections are suggested.

1.     You can ad below references line 30-33 Globally, the number of cultivatable agricultural areas is diminishing both in quality and quantity due to urbanization, natural disasters, global warming, irrational soil cultivation, and the potential uncontrolled use of pesticides, which affect soil fertility and thus the production of quality food.

A Review of Precision Irrigation Water-Saving Technology under Changing Climate for Enhancing Water Use Efficiency, Crop Yield, and Environmental Footprints. Agriculture 2024, 14, 1141

Plastic Pollution in Agriculture as a Threat to Food Security, the Ecosystem, and the Environment: An Overview. Agronomy 2024, 14, 548.

 

2.     You can add below references line 41-41 Soilless agriculture can fill the increasing food scarcity issue, especially in urban areas.

Overview of the aeroponic agriculture–An emerging technology for global food security. International Journal of Agricultural and Biological Engineering. Volume 13 Issue 1 Pages 1-10.

3.     No need to write light-emitting diodes (LEDs) again and again. After first time use, it can be used as LEDs.

Comments on the Quality of English Language

n/a

Author Response

Response to report 2 Horticulturae-3149488 R3

Dear Reviewer,

Thank you very much for taking the time to review the revised manuscript. We especially thank you for your suggestions, which will help us improve the quality of the manuscript. Below we respond to the comments in detail and have corrected the manuscript highlighting the corrections in the re-submitted file.

Comments and Suggestions for Authors

I received the revised version of the manuscript entitled: An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System for possible publication in Horticulturae. The authors have revised manuscript and it can be considered for possible publication. Some minor corrections are suggested.

1. You can add below references line 30-33 Globally, the number of cultivatable agricultural areas is diminishing both in quality and quantity due to urbanization, natural disasters, global warming, irrational soil cultivation, and the potential uncontrolled use of pesticides, which affect soil fertility and thus the production of quality food.

A Review of Precision Irrigation Water-Saving Technology under Changing Climate for Enhancing Water Use Efficiency, Crop Yield, and Environmental Footprints. Agriculture 2024, 14, 1141

Plastic Pollution in Agriculture as a Threat to Food Security, the Ecosystem, and the Environment: An Overview. Agronomy 2024, 14, 548.

Response: Thank you for recommending the references above, we added them to the relevant section in the review (now line: 33). 

2. You can add below references line 41-41 Soilless agriculture can fill the increasing food scarcity issue, especially in urban areas.

Overview of the aeroponic agriculture–An emerging technology for global food security. International Journal of Agricultural and Biological Engineering.2020, Volume 13 Issue 1 Pages 1-10.

Response: Thank you for recommending the references above, we added them to the relevant section in the review (now line: 62-63)

3. No need to write light-emitting diodes (LEDs) again and again. After first time use, it can be used as LEDs.

Response: Thank you for pointing this out, we have corrected the repetitions.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I reviewed the review manuscript submitted by Budavari et al. for possible publication in Horticulturae. The idea of the manuscript is interesting, and the authors have summarized important information. The manuscript can be considered for possible after corrections.  

The title of the manuscript can be improved. Because the authors have mainly discussed and summarized the studies on determining the effects of different lighting conditions used in vertical farms.

The abstract can be improved.

Line 13: What is LED?

Line 16: Microvegetables and baby leaves, such as lettuce, emerge as a valuable category of fresh produce with elevated levels of bioactive compounds. Revise it for clarity.

Line 18: Please delete those keywords already mentioned in the title.

Line 18: lettuce (baby-leaf) and; Lactuca  sativa are the same.

Line 24: what is 's? Please revise lines 23-26.

Line 37: I suggest adding some description about soilless farming before starting to discuss vertical farms. Soilless agriculture can fill the increasing food scarcity issue, especially in urban areas.

The introduction section can be improved. Currently, the problem statement and purpose of writing a review article are missing.

I suggest adding one paragraph discussing about the whole body of the paper such as Section 2, which discusses xyz and Section 3, which deals with xyz, and so on.

Line 50, vertical farming, it would be best to add some discussion about soilless farming and later start discussing different types of soilless farming; vertical farming is a mode of soilless farming.

What is the purpose of writing the subsections of section 2 .i.e Hydroponics, aeroponics and aquaponics?  In addition, these sections are poorly discussed, and their discussion can be improved.

Line 249-260: Do you conduct this, or have you taken these results from other studies? If taken, please revise the above paragraph, such as line 238.

Line 255: what is WL?

Line 256: what is UV-A AND UV?

Line 257: what is (RB)?

Line 262: Figure 1, what are HPS, FR and PAR?

Line 270: In Figure 2, please add the mode of cultivation, such as hydroponics or aeroponics.

Line 310: what is FW?, revise this (fresh weight FW per H2O liter) for clarity.

Line 311: that of the same crop in greenhouse or field. What do you want to say, please revise?

I suggest adding one more section about the future prospectus and recommendations for other researchers from your performed analysis (summarizing the data on lighting).

Reviewer 2 Report

Comments and Suggestions for Authors

Vertical farm lettuce production.

The article describes the cultivation techniques used on vertical farms, as well as the effect of LED spectrum on the development and yield of microgreens and baby leafy vegetables.

Some suggestions:

Title.  I suggest including “microgreens” in the title: Lettuce and microgreens production on a vertical farm.

Line 24.  [3]'s, or [3]?

Line 139-146. To this paragraph, it may be worth adding that:  green light penetrates deeper into the leaf and increases photosynthesis by stimulating chloroplasts located deep in the mesophyll. Additionally, green light is able to reach the lower part of the canopy, which is extremely important for dense canopy production techniques that are common in controlled environment agriculture.

Do subsections 5.1 and 5.2 also refer to microgreens, or to baby leafy greens? 

Line 337. What is LAI?