Vegetable Production in PFALs: Control of Micro-Environmental Factors, Principal Components and Automated Systems
, Ioanna Chatzigeorgiou 2, Michail Sismanis 3, Georgios K. Ntinas 2 and Athanasios Koukounaras 4Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis review study overviews plant factories with artificial lighting (PFALs) consisting of a number of elemental technologies.
Overall, in many parts of this study, there seems to be confusion in technical explanations between PFAL, greenhouse, and other protected horticulture, even if using the hydroponic system. Reviewing the reference again if each paper targets PFALs would be better.
Moreover, as this review covers many technical elements that make up the PFALs, more studies on each topic are recommended to gain a better technical overview of each subject. In particular, there is an increasing number of research papers on lighting, and it feels that more recent (post-2018) literature reviews should be conducted as well.
Title: It’s nice that the authors highlighted the “micro”-environmental factors, but it’s better to define the difference between the micro-environment and the just environment. What would be the difference?
Figure 1:
1) Would “climate control” mean air conditioner? And would “ventilation” mean “air circulation” or “air movement”? Ventilation means air exchange between the inside and outside of the target space. Here, air circulation or movement should fit the context instead of ventilation.
2) As for the rainwater collection tank, you can recirculate the water for cultivation in PFAL.
L.82: What would you mean by “sterilized” environment?
L.84: What would you mean by “closed” hydroponic systems?
L.85-86: It’s worth reconsidering if the hydroponic system is the only contributing factor for maximizing nutrient and water use efficiency.
L.91: What would you mean by a “closed” system?
L.93: What would you mean by a “visual control”?
L.103-108: It’s better to describe it as a general case for commercial production.
L.112-115: Worth adding more recent publications as there is some improvement.
L.129: In many cases, CO2 concentration is set over 1000 μmol mol-1 in PFALs.
L.130-132: Please confirm whether these references target PFALs or greenhouses.
L.135: It is said that, typically, heating is not used in PFALs.
L.149: It would be nicer to add more recent papers for citation, especially when it comes to cost.
L.175: It might be better to avoid such expressions like “best.”
L.185-186: Recently, most PFALs should be using LEDs, but not fluorescent lamps.
L.187: What would you mean by “intensive cultivation pattern?”
L.187-189: It is better to add a citation here.
L.195-196: It is nicer to update this information by adding more recent references.
L.203: These should not be a rule.
L.207-209: It is better to add a citation here.
L.249-251: The real-time image processing and spatial mapping systems should more or less estimate or compute the weight of plants, but I am unsure if they “accurately” calculate it.
L.286-291: Better to add a citation for updating the information (particularly L.289-291)
Author Response
This review study overviews plant factories with artificial lighting (PFALs) consisting of a number of elemental technologies.
Overall, in many parts of this study, there seems to be confusion in technical explanations between PFAL, greenhouse, and other protected horticulture, even if using the hydroponic system. Reviewing the reference again if each paper targets PFALs would be better.
Moreover, as this review covers many technical elements that make up the PFALs, more studies on each topic are recommended to gain a better technical overview of each subject. In particular, there is an increasing number of research papers on lighting, and it feels that more recent (post-2018) literature reviews should be conducted as well.
Response: The authors would like to express their gratitude to the reviewers for the time they invested for assessing our manuscript and their useful comments and suggestions. The comments were responded one-by-one below. In particular, the literature was reviewed as suggested, and recent publications were included.
Title: It’s nice that the authors highlighted the “micro”-environmental factors, but it’s better to define the difference between the micro-environment and the just environment. What would be the difference?
Response, L102-107: A definition of micro-environment was included in the Introduction, part 1.2. Specifically, micro-environmental conditions are unique factors to a single plant or to a group of plants within their growing spaces and can efficiently be controlled according to specific crops’ requirements and with view to enhancing the yield and production quality. For comparison, conditions in the just environment are common for a larger location at a given time.
Figure 1:
1) Would “climate control” mean air conditioner? And would “ventilation” mean “air circulation” or “air movement”? Ventilation means air exchange between the inside and outside of the target space. Here, air circulation or movement should fit the context instead of ventilation.
Response. As suggested, modifications were made in the figure.
2) As for the rainwater collection tank, you can recirculate the water for cultivation in PFAL.
Response. Thank you for your comment. Indeed, water can be circulated, while supplemental fresh water can be provided by rainwater collection tanks as well.
L.82: What would you mean by “sterilized” environment?
Response, L88: The term was substituted with “decontaminated”.
L.84: What would you mean by “closed” hydroponic systems?
Response, L90-91: “Closed” are hydroponic systems where the same nutrient solution is recirculated. It is now mentioned in the text.
L.85-86: It’s worth reconsidering if the hydroponic system is the only contributing factor for maximizing nutrient and water use efficiency.
Response, L92-93: Indeed, thank you for the comment. The phrase was amended to “…provides the opportunity to increase nutrient and water use efficiency”.
L.91: What would you mean by a “closed” system?
Response, L99-100: A closed circuit monitoring system is an interconnected network of sensors where all components capture and transmit data to a central control unit. It is now mentioned in the text.
L.93: What would you mean by a “visual control”?
Response, L98-102. A closed circuit monitoring system ensures constant check of the environmental conditions, while it facilitates observation of the crop status. It is now mentioned in the text.
L.103-108: It’s better to describe it as a general case for commercial production.
Response, L118-122: Indeed, this part was amended according to your suggestion.
L.112-115: Worth adding more recent publications as there is some improvement.
Response, L128-133: The literature was reviewed and recent articles were added as suggested.
L.129: In many cases, CO2 concentration is set over 1000 μmol mol-1 in PFALs.
Response, L147. We would like to thank the reviewer for his comment. We revised the CO2 concentration value to 800-2000, also checking the relevant references.
L.130-132: Please confirm whether these references target PFALs or greenhouses.
Response, L148-151. These references are related to controlled environment in greenhouses but also target PFALs.
L.135: It is said that, typically, heating is not used in PFALs.
Response, L153. Indeed, it is said that typically, heating is not used in PFALs, however when PFALs are not well insulated or when the external temperature is low in winter time, heating can be applied from an AC unit. We added an AC unit to Figure 1 to reflect this comment.
L.149: It would be nicer to add more recent papers for citation, especially when it comes to cost.
Response, L175-186. The literature was reviewed and recent articles were added as suggested.
L.175: It might be better to avoid such expressions like “best.”
Response, L205: The expression “the best” was changed as suggested.
L.185-186: Recently, most PFALs should be using LEDs, but not fluorescent lamps.
Response, L216-217: This sentence was amended as suggested.
L.187: What would you mean by “intensive cultivation pattern?”
Response, L217-219: This sentence was amended as suggested. PFALs are systems of intensive crop cultivation, thus, the light sources are placed in a relatively thick array in order to maximize the light-use efficiency.
L.187-189: It is better to add a citation here.
Response, L221: Citations were added as suggested.
L.195-196: It is nicer to update this information by adding more recent references.
Response, L227-228: The information of this part was updated and a recent citation was added as suggested.
L.203: These should not be a rule.
Response, L239-240: This sentence was amended as suggested.
L.207-209: It is better to add a citation here.
Response, L246: A citation was added as suggested.
L.249-251: The real-time image processing and spatial mapping systems should more or less estimate or compute the weight of plants, but I am unsure if they “accurately” calculate it.
Response, L286-289: This sentence was changed as follows: This real-time image processing and spatial mapping systems can calculate the weight of plants with an acceptable level of accuracy and also give an estimation of future plant yield, ahead of harvesting.
L.286-291: Better to add a citation for updating the information (particularly L.289-291)
Response, L329: A citation was added as suggested.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis MS makes an in-depth analysis of the micro-environmental factors, the principal components, as well as the automated systems in the plant factories with artificial lighting (PFALs), which has high reference value and provides several future perspectives that can be considered for indoor cultivation in the following years. However, there are important questions and points that the authors should clarify.
1. Figure 1. is a little simple, environmental control systems (temperature and humidity control), and nutrient solution circulation systems should be reflected in this figure.
2. In the introduction section, the authors need to pay attention to the structural framework. Line 41-54, the authors firstly introduce the new challenges such as food safety, security, and so on. Next, they propose that the solution to the challenge is local production and short supply chains that are less affected by international restrictions and are in close proximity to the stakeholders. And then point that a 27% decrease in the growth cycle duration when rocket baby leaves were cultivated in a PFAL compared to a greenhouse in winter time. The section is poorly organized and a little confusing. On the one hand, the food safety and security can not be solved by local production and short supply chains, on the other hand, the introduction of PFAL about short growth cycle duration does not fit the context.
3. Besides, the authors need to pay more attention to the connection between paragraphs of the introduction and the connection between paragraph content and PFAL. Line 55-61, the authors take a long time to introduce the importance of vegetables but take a short time to associate vegetables with PFAL.
4. Line 117-156, the authors described environmental control including humidity, CO2 concentration, temperature, and lighting. Please supplement more advanced control strategies and methods for these environmental factors.
5. Line 293-306, the authors introduced the control of the nutrient solution, besides the mild salinity of the nutrient solution, what else is there to enhance the quality of specific crops by controlling the nutrient solution? (such as nitrogen limitation).
6. The contents of the control of light properties need to be refined and simplify.
Author Response
This MS makes an in-depth analysis of the micro-environmental factors, the principal components, as well as the automated systems in the plant factories with artificial lighting (PFALs), which has high reference value and provides several future perspectives that can be considered for indoor cultivation in the following years. However, there are important questions and points that the authors should clarify.
Response. The authors would like to express their gratitude to the reviewers for the time they invested for assessing our manuscript and their useful comments and suggestions. The comments were responded one-by-one below.
- Figure 1. is a little simple, environmental control systems (temperature and humidity control), and nutrient solution circulation systems should be reflected in this figure.
Response. As suggested, environmental control systems and nutrient solution circulation systems were included in the figure.
- In the introduction section, the authors need to pay attention to the structural framework. Line 41-54, the authors firstly introduce the new challenges such as food safety, security, and so on. Next, they propose that the solution to the challenge is local production and short supply chains that are less affected by international restrictions and are in close proximity to the stakeholders. And then point that a 27% decrease in the growth cycle duration when rocket baby leaves were cultivated in a PFAL compared to a greenhouse in winter time. The section is poorly organized and a little confusing. On the one hand, the food safety and security can not be solved by local production and short supply chains, on the other hand, the introduction of PFAL about short growth cycle duration does not fit the context.
Response, L49-54. Indeed, the point about “27% decrease in the growth cycle duration …” is possibly out of order and is not related to this paragraph, thus it was removed. Besides, regarding the comment about food safety and security, our intention was to provide possible answers or tools to enhance food safety and security such as local production and short supply chains. It was not our intention to state that PFALs are the only way of achieving this. This part was amended.
- Besides, the authors need to pay more attention to the connection between paragraphs of the introduction and the connection between paragraph content and PFAL. Line 55-61, the authors take a long time to introduce the importance of vegetables but take a short time to associate vegetables with PFAL.
Response, L61-65. This part was amended according to your suggestions. Besides, we would like to stress out that the suitable vegetables for PFALs were already discussed in the end of subsection 1.2. It is now mentioned in the text.
- Line 117-156, the authors described environmental control including humidity, CO2 concentration, temperature, and lighting. Please supplement more advanced control strategies and methods for these environmental factors.
Response, L175-186. The literature was reviewed and recent articles were added as suggested.
- Line 293-306, the authors introduced the control of the nutrient solution, besides the mild salinity of the nutrient solution, what else is there to enhance the quality of specific crops by controlling the nutrient solution? (such as nitrogen limitation).
Response, L332-347. A paragraph dealing with the effects of nutrient solution was added as suggested.
- The contents of the control of light properties need to be refined and simplify.
Response, L367-373. As suggested, an introducing paragraph was included in order to simplify the content of this section.
