Light Down-Conversion Technology Improves Vegetative Growth, Berry Production, and Postharvest Quality in Tunnel-Cultivated Blueberry

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

L 111 - describe what "bud burst" stage means (e.g., vegetative or floral buds?).  What were they grown in before transplanting?  describe the size and uniformity of plants at transplanting - without this, the increases in biomass during the trial are meaningless.

L113- fully describe the growing media composition.  How was pH and EC measured?  done only once?

L116 - how much sulfosprint was added?

L118- describe the sourcewater, including pH, EC and alkalinity.  How were the plants watered (top, drip, subirrigated), what was the leaching fraction and quality (EC & pH) of the leachate?

L119- Much more information is needed here to describe the "growing conditions under each film".  We need to know what sensor technology was used (make, model, last calibrated), where it was placed relative to the treatment plants, logging interval.  There should be data for every tunnel, each with its own average and error term (Standard deviation please, but also include "n").

I noted in another manuscript by the same author ( https://doi.org/10.3390/horticulturae10101046) that aerial environment conditions were only monitored in one tunnel with the justification that the open ends makes the environment uniform - this is not good enough (just speculation).

L122- should this be L x W x H? What is the shape of the tunnels?  Adding a picture of the entire setup (or at least a schematic) would be very helpful to readers to visualize the setup.

L122- seems the floor ares was ~ 24 m^2, describe how the (10) plants were positioned in this area, including planting density, border plants etc.

L130 - is colorless the same as transparent?  I can almost guarantee that this was not neutral density material, so some alteration of the sunlight spectrum is probable.

L136 - The citation style in the manuscript (name date) does not match the bibliography (sequential number) - this makes it very difficult for the reader to be sure to find the correct reference.  Is El Horri et al. (2024b). ref 19 or 20?  There is no "b" in the references section and as far as I can tell "El Horri et al" is only references once in the entire manuscript - so which reference is this?

L136- there are problems with the spectral modifications information provided in this reference. There is no description on how the measurements were made (e.g., date, time, sunlight conditions), how the spectrometer was setup (and how it was calibrated).  Also the Y-axis is in absolute units - clearly the 4 measurements were taken at different times - so absolute irradiance does not control for varying incident lighting levels during the 4 measurements. These should be converted to relative units for more relevant comparison of photo conversions. I also recommend converting the irriadiance to photon flux units.

L125 - the authors appear to define individual colors by wavebands (e.g., blue 420 to 495nm) somewhat arbitrarily, but there are gaps between each color band (e.g., 495 to 520 nm).  1) these wavebands are not conventional 2) the gaps need to be filled so the entire spectrum is accounted for 3) UV is normally subdivided into UVB and UVA (normally at 315 or 320 nm) because these wavebands have unique impacts on plants.

L136, this information needs to be adjusted according to the revisions suggested above (e.g., define all wavebands in the 320 to 800nm range), change irradiance to photon flux units.

L136 - please describe which condition these conversions are in respect to (i.e,, unfiltered sunlight or below the control covering). If sunlight, then please add the control covering as well.  if the control covering, please relate control to sunlight (it is not a neutral density film).

L139 - one of the most interesting spectrum differences between the colored films and the clear is in the UVA region - please expand on this.

L147 - seems there are 10 plants, so which 5 were evaluated?  Were the same plants evaluated at time A&B?  why does n=4 for total fruit production?

L151 - more detailed information is needed to describe each measurement, the value for n, how tissues were sampled. image J is a software tool - it cannot be used to measure leaf area without digital images - how were the plant tissues processed to make these images and how wad imaje J used to estimate leaf area? which leaves were chosen for measuring thickness?  How was "newly formed biomass" separated from previously-present biomass?

L160 - only 4 leaves per treatment were used to evaluate DM content?  That is a ridiculously low number of samples for this parameter.

L165 - no mention of when or how FW was measured prior to drying

L194 - were these plants moved outdoors "under sunlight".  Which leaf chamber was used in the LI6400?  How did individual leaf area compare to the size of the chamber cuvette? What were the light conditions (inside the cuvette) during each of these measurements ? Note that the light sensor inside the cuvette is much more sensitive to spectrum than the LI190 quantum sensor on the outside of the cuvette

L303 - Please include a full description of the experimental design.  My understanding is that this trial has 4 tunnels, each with a different poly film. And 10 plants per tunnel. Each of these plants represents a subsample, but it appears that the statistical analysis is using them as replicates.  If there are no true replications of the treatments in this experiment, all of the statistical analysis is invalidated. Effectively, this manuscript describes a case study, which is probably not good enough for publication in a peer-reviewed journal such as Agronomy.

Comments on the Quality of English Language

I only read the abstract and M&M - there could be improvements in the quality of English.

Just one example from the Abstract:

"Red film induced plant biomass" - this does not make any sense.  perhaps "The red film promoted increases in aboveground biomass"

Author Response

Reviewer 1

L 111 - describe what "bud burst" stage means (e.g., vegetative or floral buds?). What were they grown in before transplanting?  describe the size and uniformity of plants at transplanting - without this, the increases in biomass during the trial are meaningless.

We thank the reviewer for this relevant comment. We were aware of the importance of the standardized shape of our plants, therefore plants of an average of 3 woody twigs were selected for the experiment. The plants were purchased from a nursery; therefore, they were subjected to the same growing conditions prior to the transplant under the tunnels, growing in a commercial peat. The information was added and highlighted in the manuscript.

L113- fully describe the growing media composition. How was pH and EC measured? done only once?

We thank the reviewer for this relevant comment. The idea was to choose an optimal substrate for blueberry rhizosphere development and plant growth and for this reason we purchased the professional TYP 5 acidic substrate by Vialca srl (Uzzano, Pistoia, Italy). The substrate pH and EC were measured once a week, not exceeding 10% of the previous time measured values. We added all this information in paragraph 2.1 of the manuscript.

L116 - how much sulfosprint was added?

We thank the reviewer for this question. The sulfoprint was mixed with the substrate during the transplanting.

L118- describe the sourcewater, including pH, EC and alkalinity. How were the plants watered (top, drip, subirrigated), what was the leaching fraction and quality (EC & pH) of the leachate?

We thank the reviewer for the comment. Description of the sourcewater and the kind of irrigation was reported in paragraph 2.1 of the manuscript. However, the leaching fraction and the leachate quality were not considered as we were able to measure directly the substrate pH and EC and it was not an aim of the present study.

L119- Much more information is needed here to describe the "growing conditions under each film". We need to know what sensor technology was used (make, model, last calibrated), where it was placed relative to the treatment plants, logging interval. There should be data for every tunnel, each with its own average and error term (Standard deviation please, but also include "n").

We thank the reviewer for his/her remark. We utilized a data logger (Tinytag Ultra 2 – TGU-4500, Gemini Data Loggers, Chichester, UK) Ltd. installed under one of the four experimental films. Indeed, the weather conditions were not affected by the covered film since the tunnel was open and strictly affected by outside environmental conditions. Moreover, the logging interval was 30 minutes for all the trial period and we added the standard deviation of each weather parameters. We added this explanation in the paragraph 2.1.

I noted in another manuscript by the same author (https://doi.org/10.3390/horticulturae10101046) that aerial environment conditions were only monitored in one tunnel with the justification that the open ends makes the environment uniform - this is not good enough (just speculation).

We thank the reviewer for his relevant comment. Our argument for the justification of one tunnel monitoring was also backed with data proof, as we performed a test by putting 4 datalogger simultaneously under the 4 tunnels. Temperature and relative humidity data were analyzed after 1 week and no significant differences in both parameters were raised as you can see in the Tables below.

Tables. Relative humidity (RH) percentage and temperature measured under each film during a week. Means were subjected to one-way ANOVA with type of film as variability source. The lack of letters indicates that means are not statistically different at p ≤ 0.05, as determined by Fisher's least significant difference post-hoc test.

RH (%)	Cnt film	Red film	Pink film	Blue film
Day 1	56.15±27.11	56.16±28.52	57.31±27.59	57.70±26.61
Day 2	68.82±25.06	68.96±25.21	69.96±25.42	69.80±24.62
Day 3	65.46±28.62	64.17±29.90	67.63±27.92	68.34±27.40
Day 4	60.52±30.26	59.06±31.70	61.59±31.15	63.30±29.47
Day 5	61.58±28.44	60.23±30.21	63.01±29.27	64.55±27.71
Day 6	60.06±28.41	59.55±29.21	61.49±28.96	63.23±27.32
Day 7	62.98±14.05	64.21±15.17	64.88±16.33	64.21±16.02
Temperature (°C)	Cnt film	Red film	Pink film	Blue film
Day 1	26.04±12.47	26.65±13.18	25.90±12.67	25.13±11.10
Day 2	22.73±9.67	22.97±10.03	22.45±9.97	22.32±9.21
Day 3	25.04±10.62	25.98±11.68	24.35±10.28	23.88±9.69
Day 4	27.07±12.86	28.25±14.01	26.95±13.21	25.72±11.49
Day 5	27.41±11.64	28.60±12.79	27.14±11.83	25.97±10.39
Day 6	28.65±11.61	29.16±12.06	28.43±11.83	27.03±10.14
Day 7	24.11±3.75	24.09±4.06	23.94±4.40	24.21±4.53

 

L122- should this be L x W x H? What is the shape of the tunnels? Adding a picture of the entire setup (or at least a schematic) would be very helpful to readers to visualize the setup.

We thank the reviewers for this comment. The tunnel has a hoop structure. We added a figure of the entire set up in the manuscript (Figure 1).

L122- seems the floor area was ~ 24 m^2, describe how the (10) plants were positioned in this area, including planting density, border plants etc.

We thank the reviewer for the comment. In the experimental set up, plants were positioned in two lines under each tunnel, occupying both tunnel sides with inter-space (between the lines) of 3 m and intra-space (between two plants of each line) of 30 cm. The details were added and highlighted in the manuscript.

L130 - is colorless the same as transparent? I can almost guarantee that this was not neutral density material, so some alteration of the sunlight spectrum is probable.

We thank the reviewer for the comment. The control polyethylene film was transparent (we removed the word “colorless” and we added the word “transparent”). This film was made by the same material as the other films under investigation, avoiding the fluorescent chromophore for the conversion effect. Thus, of course, under this film some alterations of the sunlight spectrum occurred; however, we utilized this film as control because the alterations of the sunlight spectrum happening under this transparent film were equal to the sunlight spectrum alterations happening under each light conversion film, except for the light conversion specific of each colored film.

L136 - The citation style in the manuscript (name date) does not match the bibliography (sequential number) - this makes it very difficult for the reader to be sure to find the correct reference.  Is El Horri et al. (2024b). ref 19 or 20?  There is no "b" in the references section and as far as I can tell "El Horri et al" is only references once in the entire manuscript - so which reference is this?

We thank the reviewer for this suggestion. The correction was performed and highlighted in the manuscript.

L136- there are problems with the spectral modifications information provided in this reference. There is no description on how the measurements were made (e.g., date, time, sunlight conditions), how the spectrometer was setup (and how it was calibrated). Also the Y-axis is in absolute units - clearly the 4 measurements were taken at different times - so absolute irradiance does not control for varying incident lighting levels during the 4 measurements. These should be converted to relative units for more relevant comparison of photo conversions. I also recommend converting the irriadiance to photon flux units.

We thank the reviewer for the comment. The spectral measurements were performed 03/05/2024 during midday using the new films by fixing the spectroradiometer probe (Ocean HR Series: HR2 Spectrometer, Ocean Optics, Florida, USA) vertically and measuring all films transmittance within 15 minutes period of time, making sure that the sky was clear and no clouds were overpassing at the time of the measurement. The measurements were done in 3 replicates for each treatment and the average irradiance was used for the graph. The dark calibration was carried out prior to the measurement.

We added the figure with converted irradiance in photon flux units and a figure reporting the difference rate of light transmittance of each colored film in respect to the control in supplementary material (Figure S1 and S2).

L125 - the authors appear to define individual colors by wavebands (e.g., blue 420 to 495nm) somewhat arbitrarily, but there are gaps between each color band (e.g., 495 to 520 nm). 1) these wavebands are not conventional 2) the gaps need to be filled so the entire spectrum is accounted for 3) UV is normally subdivided into UVB and UVA (normally at 315 or 320 nm) because these wavebands have unique impacts on plants.

We thank the reviewer for the comment. The definition of the individual colors was carried out on the basis the spectrum measurement of the light conversion films and available characterization of light colors in literature. In fact, we tried to identify, using wavebands, the parts of the spectrum that were absorbed and the ones transmitted in order to clarify to the reader the exact converted wavebands. This was also intentionally done since there are several light conversion films used in literature, and it is relevant to specify the optical characteristics of our treatments. The wavebands that were not specified were not targeted by light conversion technology.

L136, this information needs to be adjusted according to the revisions suggested above (e.g., define all wavebands in the 320 to 800nm range), change irradiance to photon flux units.

We thank the reviewer for his comment. There are no significant differences in the irradiance between the wavebands. The information provided is rates of decrease/increase in irradiance for each waveband range respectively to the control polyethylene film.

L136 - please describe which condition these conversions are in respect to (i.e,, unfiltered sunlight or below the control covering). If sunlight, then please add the control covering as well. If the control covering, please relate control to sunlight (it is not a neutral density film).

We thank the reviewer for his comment. As mentioned above, the rates represent decrease/increase in irradiance for each waveband range respectively to the control polyethylene film. The rate of the control in comparison to the sunlight were assed and highlighted in the manuscript.

L139 - one of the most interesting spectrum differences between the colored films and the clear is in the UVA region - please expand on this.

We thank the reviewer for his comment. Actually, we did not divide the percentages of each UV part range, because we only focused on 300 to 390 nm. Whereas UV-B alone is around 280 to 315 nm and UV-A is 315 to 400 nm. We made the calculations once again for the requested range 315 to 400 nm and it is nearly equal to the previous range used in the results calculations as you can see from the Table below. For this reason, we did not add any additional information in the manuscript.

	UV range 300 to 390	UV-A range 315 to 400
Red film	-75.81%	-76.43%
Pink film	-75.57%	-76.07%
Blue film	-80.85%	-80.03%
Average	-77.41%	-77.51%

 

L147 - seems there are 10 plants, so which 5 were evaluated? Were the same plants evaluated at time A&B? why does n=4 for total fruit production?

We thank the reviewer for the comment. All the 10 plants were evaluated, but the number of replicates was reduced to 5 in order to eliminate outliers and ensure data normality prior to one-way ANOVA application. The same pattern was utilized for the total fruit production data.

L151 - more detailed information is needed to describe each measurement, the value for n, how tissues were sampled. image J is a software tool - it cannot be used to measure leaf area without digital images - how were the plant tissues processed to make these images and how wad imaje J used to estimate leaf area? which leaves were chosen for measuring thickness? How was "newly formed biomass" separated from previously-present biomass?

We thank the reviewer for the comment. At the end of the experiment, we made sure that plant newly formed biomass (leaves and new shoots) was detached from the old twigs using pruning shears and then weighted for the new biomass total weight. The newly detached leaves were used for leaf thickness and measurement followed by scanning to generate digital leaf pictures processed in ImageJ for leaf area measurement. We added this information to the manuscript.

L160 - only 4 leaves per treatment were used to evaluate DM content? That is a ridiculously low number of samples for this parameter.

We thank the reviewer for the comment. For the evaluation of leaf dry matter, a medium number of 5 discs from 20 leaves of each plant were used for each biological replicate, then 4 biological replicates representing plants (averaging all values obtained by the 20 leaves for each plant) per treatment were evaluated. Therefore, we think that the 4 values inserted in the manuscript were representative for four whole plants.

L165 - no mention of when or how FW was measured prior to drying

Thank you for the suggestion. The information was clarified and highlighted in the manuscript in paragraph 2.2.

L194 - were these plants moved outdoors "under sunlight". Which leaf chamber was used in the LI6400? How did individual leaf area compare to the size of the chamber cuvette? What were the light conditions (inside the cuvette) during each of these measurements? Note that the light sensor inside the cuvette is much more sensitive to spectrum than the LI190 quantum sensor on the outside of the cuvette

We thank the reviewer for the suggestion. The plants were measured under the light conditions of the light conversion films and the control. The transparent leaf chamber was used in order to capture transmitted light inside the tunnel. The leaves were able to cover the whole chamber of 6 cm². The PAR inside the chamber was ranging between 800 and 1000 µmol m^–2 s^–1 in T1 and between 400 and 700 µmol m^–2 s^–1 in T2.

L303 - Please include a full description of the experimental design. My understanding is that this trial has 4 tunnels, each with a different poly film. And 10 plants per tunnel. Each of these plants represents a subsample, but it appears that the statistical analysis is using them as replicates. If there are no true replications of the treatments in this experiment, all of the statistical analysis is invalidated. Effectively, this manuscript describes a case study, which is probably not good enough for publication in a peer-reviewed journal such as Agronomy.

We thank the reviewer for the comment. This is an experiment that has the aim of evaluating the effects of light conversion technology on Blueberry plants. The experimental design was performed by covering 4 tunnels with 3 light conversion films and 1 transparent film. The plants transplanted under each tunnel represent our biological replicates, each plant represents an individual that developed under light environmental conditions modulated by light conversion films. Under each film, 10 individual plants were transplanted and developed new biomass and new flowers and fruit inside the tunnels. Therefore, the collected data was either nondestructive (during plant development) or destructive (when sampling of leaves and fruits at the end of the experiment) in order to understand the link between plants growth, photosynthesis and final production. The statistical analysis was conducted considering the biological replicates that represent the overall effect of light conversion technology on plant physiology and production.

I only read the abstract and M&M - there could be improvements in the quality of English. Just one example from the Abstract: "Red film induced plant biomass" - this does not make any sense. perhaps "The red film promoted increases in aboveground biomass"

We thank the reviewer for this comment. We revised the English deeply.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The results suggest the relevance of Red film in enhancing plant biomass, Red and Blue films in improving fruit yield and maintaining nutraceutical post-harvest quality in blueberry plants. However, the mechanistic claims would benefit from functional validation and deeper hormonal profiling. Therefore, several areas could be strengthened to enhance the robustness and impact of the findings.

1 The title is long, please modify it. For example, Impact of Light Down-Conversion Films on Growth, Yield, and Postharvest Quality of Blueberry (Vaccinium corymbosum L. cv. Duke)

2 In abstract section, key results should be quantified more precisely.

3 Recent studies of light quality should be reviewed in introduction section.

4 Define “class 3” fruit diameter earlier and explain why this class was prioritized for storage.

5 Principal component analysis or correlation analysis is necessary.

6 Standardize the format of figures in the thesis, including font style, etc.

7 Discuss why Pink film reduced Pn at t2 despite increased leaf thickness-could it relate to energy partitioning?

8 Link TPC/TAC stability under Blue film to its role in UV-to-blue conversion, which may upregulate antioxidant pathways (cite Yang et al., 2019).

Author Response

Referee 2:

The results suggest the relevance of Red film in enhancing plant biomass, Red and Blue films in improving fruit yield and maintaining nutraceutical post-harvest quality in blueberry plants. However, the mechanistic claims would benefit from functional validation and deeper hormonal profiling. Therefore, several areas could be strengthened to enhance the robustness and impact of the findings.

1 The title is long, please modify it. For example, Impact of Light Down-Conversion Films on Growth, Yield, and Postharvest Quality of Blueberry (Vaccinium corymbosum L. cv. Duke)

We thank the reviewer for the comment. The title was adapted to the suggestion.

2 In the abstract section, key results should be quantified more precisely.

In abstract, key results were quantified more precisely.

3 Recent studies of light quality should be reviewed in the introduction section.

We thank the reviewer for the comment. Two references were added in the introduction.

4 Define “class 3” fruit diameter earlier and explain why this class was prioritized for storage.

We thank the reviewer for the suggestion. Class 3 was characterized by 1.3– 1.6 cm in diameter. It was the most abundant class in terms of fruit, giving the possibility to perform homogenized boxes of standardized fruit size.

5 Principal component analysis or correlation analysis is necessary.

We thank the reviewer for this comment, but we do not understand what data the reviewer would like to correlate through a correlation or PCA. If some specification is given in terms of the data to be correlated and in terms of the purpose and value of the new graph once it has been inserted into the manuscript, then we could carry out the graphical analysis.

6 Standardize the format of figures in the thesis, including font style, etc.

We thank the reviewer for the suggestion; we modified the graphs accordingly.

7 Discuss why Pink film reduced Pn at t2 despite increased leaf thickness-could it relate to energy partitioning?

We thank the reviewer for this suggestion. We discussed this behavior at the end of paragraph 4.1.

8 Link TPC/TAC stability under Blue film to its role in UV-to-blue conversion, which may upregulate antioxidant pathways (cite Yang et al., 2019).

We thank the reviewer for the suggestion; the explanation was added to the discussion with the mentioned reference.

Reviewer 3 Report

Comments and Suggestions for Authors

TITLE

Major Issues:

1. Incomplete Technology Specification: The term "Light Down-Conversion Films" lacks proper technical precision. Should specify "Luminescent Down-Conversion Films" or "Photoluminescent Spectrum-Converting Films" to distinguish from other light modification technologies.
2. Missing Controlled Environment Context: The title fails to indicate this was conducted under protected cultivation, which is crucial for light modulation studies. Consider adding "under Protected Cultivation" or "in Tunnel Production Systems."

Suggested title : Light down-conversion technology improves vegetative growth, berry production, and postharvest quality in tunnel-cultivated blueberry

 

ABSTRACT

1. Inadequate Light Characterization: The abstract mentions "convert green light into red light" and "ultraviolet light into blue light" but provides no quantitative spectral data. Missing PPFD values, wavelength ranges, or conversion efficiency percentages.
2. Undefined Technical Terms: "Red and Pink films" and "Blue and Pink films" classification system isn't explained. The distinction between film types needs clarification upfront.
3. Missing Environmental Controls: No mention of controlled environment conditions (temperature, humidity, CO2) that are essential for light modulation studies.
4. Incomplete Postharvest Methodology: States "freshly harvested blueberries were subjected to postharvest experiments" without specifying storage conditions, duration, or evaluation parameters.
5. Weak Practical Implications: The conclusion lacks commercial relevance or energy efficiency considerations critical for controlled environment horticulture.

Specific Technical Corrections suggested:

• Add spectral conversion data: "converting UV (300-390 nm) to blue (420-495 nm) radiation"
• Include environmental conditions: "under controlled tunnel conditions (27.3±11.7°C, 51.9±21.6% RH)"

FUNDAMENTAL TECHNICAL CONCERNS

1. Light Technology Misrepresentation: The study describes "light converting films" but doesn't adequately explain the quantum dot or phosphor-based conversion mechanisms, which is essential for reproducibility.
2. Missing Energy Balance: No discussion of how spectrum conversion affects overall light transmission efficiency or energy balance under the films.
3. Inadequate Temporal Consideration: The abstract doesn't address how light treatments interacted with natural seasonal variations or photoperiod changes.

 

 Suggested KEYWORDS

Vaccinium corymbosum  , luminescent down-conversion films, photoselective cultivation, controlled environment horticulture, fruit anthocyanins

 

INTRODUCTION

 

1. Inadequate Light Technology Characterization

Lines 78-81: The description of Light Cascade® technology is scientifically imprecise. "Allow the absorbance of UV and green wavelengths, re-emitting into blue (400-500 nm) and red (600-700 nm) wavelengths" oversimplifies quantum dot or phosphor-based down-conversion mechanisms. Missing:

• Quantum efficiency specifications
• Stokes shift explanations
• Energy conversion losses
• Spectral bandwidth precision

2. Incomplete Photobiology Foundation

Lines 53-69: The section on light effects lacks fundamental photoreceptor mechanisms. Missing discussion of:

• Phytochrome (red/far-red perception)
• Cryptochrome (blue/UV-A perception)
• Phototropin (blue light phototropism)
• Light signaling cascade pathways
• Photomorphogenic responses specific to Vaccinium

3. Insufficient Controlled Environment Context

Lines 70-75: The protected cultivation discussion is superficial. Critical omissions:

• Energy balance considerations under light-modifying covers
• Microclimate modifications (temperature, humidity, VPD)
• Light transmission efficiency losses
• Economic feasibility of spectrum conversion technologies

MAJOR SCIENTIFIC GAPS

1. Species-Specific Literature Deficiency

Lines 47-52: While mentioning Vaccinium species, the introduction fails to address:

• Cultivar-specific light responses in V. corymbosum
• Photoperiod requirements for flower induction
• Light intensity thresholds for optimal fruit development
• Genetic variation in photomorphogenic responses

2. Incomplete Technology Comparison

Lines 76-91: The LED vs. light conversion film comparison lacks critical distinctions:

• Energy consumption differences
• Installation and maintenance costs
• Light uniformity distribution patterns
• Durability under agricultural conditions
• Spectral stability over time

3. Missing Postharvest-Light Interaction

Lines 100-107: The objectives mention postharvest quality but the introduction provides no foundation for:

• Pre-harvest light effects on postharvest physiology
• Bioactive compound stability mechanisms
• Storage quality implications of light-modified fruit development

METHODOLOGICAL CONCERNS

1. Insufficient Gap Identification

The introduction fails to clearly articulate:

• Why existing LED studies aren't sufficient
• What specific knowledge gaps light conversion films address
• How this technology differs from photoselective nets or films already studied

2. Weak Commercial Justification

Lines 82-91: References to strawberry and raspberry studies don't establish:

• Scalability to commercial blueberry production
• Cost-benefit analysis framework
• Energy efficiency comparisons
• Regional applicability considerations

LITERATURE REVIEW DEFICIENCIES

1. Outdated Technology Context

Lines 78-81: The Light Cascade® description needs:

• Comparison with competing quantum dot technologies
• Reference to recent advances in perovskite-based converters
• Discussion of spectral conversion efficiency benchmarks

Suggested SPECIFIC IMPROVEMENT RECOMMENDATIONS

1. Add Technical Precision Section

Insert after line 81: "Light down-conversion efficiency, measured as the ratio of converted photons to absorbed photons, typically ranges from 60-90% depending on the phosphor or quantum dot material used. Energy losses through Stokes shift must be considered when evaluating the net photosynthetic benefit of spectrum conversion technologies."

2. Include Photoreceptor Mechanisms

Insert after line 69: "These responses are mediated by specific photoreceptors: phytochromes detecting red/far-red ratios crucial for stem elongation and flowering, cryptochromes responding to blue light for chlorophyll synthesis and stomatal regulation, and phototropins governing directional growth responses."

3. Strengthen Commercial Context

Replace lines 70-75 with: "Protected cultivation systems offer precise environmental control but introduce challenges in light transmission and spectrum modification. While LED supplementation provides spectral control, energy costs can exceed $0.50 per kg of fruit produced. Passive spectrum conversion technologies represent a potentially more economical approach to light quality management."

4. Clarify Knowledge Gap

Add before objectives (line 100): "Despite extensive research on LED lighting effects in berries, the specific impacts of passive spectrum conversion on the intricate relationships between plant development, fruit biochemistry, and postharvest stability remain unexplored in V. corymbosum production systems."

 

 

 

 

METHODOLOGY

 

1. Inadequate Light Characterization

Lines 145-168: The light spectrum methodology is fundamentally flawed:

• Missing baseline measurements: No quantification of natural solar irradiance conditions before film application
• Inadequate spectroradiometry: Single measurements with HR2 Spectrometer insufficient for temporal variations
• No PPFD documentation: Absence of photosynthetic photon flux density measurements (μmol m⁻² s⁻¹)
• Missing quantum efficiency: No conversion efficiency data for the down-conversion films
• Temporal gaps: No monitoring of spectral changes over the 108-day experimental period

2. Uncontrolled Environmental Variables

Lines 129-135: The environmental monitoring is inadequate:

• Single data logger: One sensor for four tunnels cannot capture spatial variability
• No microclimate differentiation: Films likely create different temperature/humidity profiles
• Missing VPD calculations: Vapor pressure deficit critical for stomatal responses
• No CO₂ monitoring: Essential for photosynthetic interpretations
• Absent wind speed data: Affects transpiration and gas exchange

3. Flawed Experimental Design

Lines 136-140: The tunnel arrangement lacks proper experimental controls:

• Pseudoreplication: Only one tunnel per treatment = no true replication
• No randomization: Fixed spatial arrangement introduces confounding variables
• Missing control validation: No verification that "control" film truly represents baseline conditions
• Inadequate plant spacing: 30 cm between pots insufficient for eliminating plant-to-plant shading effects

1. Inadequate Anatomical Methodology

Lines 197-215: The leaf anatomy protocol lacks precision:

• No standardization: No control for leaf age, position, or light exposure history
• Missing measurements: No stomatal density, chloroplast counts, or cell size analysis
• Improper fixation timing: No specification of time-of-day for tissue collection

FRUIT AND POSTHARVEST PROTOCOL

1. Arbitrary Fruit Classification

Lines 237-249: The fruit grading system is scientifically meaningless:

• No commercial standards: Classes don't align with industry grading systems
• Missing weight correlation: Diameter alone insufficient for quality assessment
• No maturity indexing: Harvest timing based solely on color is inadequate

 STATISTICAL ANALYSIS INADEQUACIES

Lines 333-348: The statistical approach is inappropriate for the experimental design:

• Wrong ANOVA model: Should use mixed-effects models for repeated measures
• Inadequate multiple comparisons: Fisher's LSD too liberal for multiple treatments
• Missing interaction analysis: Treatment × time interactions not properly  (Example: Figure 2 b, c  and d. With  significative interaction , where are the capital letters?.  
• Suggestion:
• "Statistical analyses employed mixed-effects models (lme4 package in R) to account for repeated measures and nested experimental structure. Treatment effects were analyzed using restricted maximum likelihood estimation with Tukey's HSD for multiple comparisons.

 

RESULTS

Missing Critical Data

• No root biomass measurements: Essential for understanding total plant response to light treatments
• Absent allometric relationships: No shoot:root ratios or carbon allocation patterns

3.2 GAS EXCHANGE AND PIGMENT MEASUREMENTS

Figure 2, Lines 379-414:

• Missing environmental context: No correlation with actual PPFD or spectral quality under films

3.3 LEAF THICKNESS INVESTIGATION

Table 3, Lines 441-447:

• Missing standardization: No control for leaf age, position, or development stage

Incomplete Anatomical Analysis

Lines 429-438:

• Missing functional measurements: No stomatal density, chloroplast counts, or intercellular air space analysis
• No correlation with physiology: Anatomical changes not linked to gas exchange or pigment data

 3.4 FLOWER AND FRUIT YIELD MEASUREMENTS

Lines 450-461:

• Single fruit weight measurement insufficient: Need fruit density, firmness, and shape measurements
• Missing maturity indexing: No assessment of fruit development uniformity across treatments

3.5 POSTHARVEST EXPERIMENT EVALUATION

Table 5, Lines 471-498:

• Arbitrary quality classification: Fruit diameter classes lack commercial or scientific justification
• Missing harvest maturity standardization: No objective maturity indices beyond visual color assessment

3.5.2 Storage Quality Analysis

Figures 4-7, Lines 500-574:

• Inadequate temporal resolution: T0-T3 intervals can  miss critical metabolic transition periods

FUNDAMENTAL RESULT PRESENTATION ERRORS

1. Statistical Reporting Deficiencies

• Inadequate multiple comparison corrections: Fisher's LSD too liberal for multiple treatment comparisons

3. Data Integration Failures

• Disconnected datasets: No correlation analysis between plant growth, fruit yield, and postharvest quality

 CORRECTIONS SUGGESTED

1. Enhanced Statistical Analysis

Replace inadequate statistics with:

• Mixed-effects models accounting for repeated measures and tunnel clustering
• Proper multiple comparison procedures (Tukey's HSD or Bonferroni)

3. Improved Data Presentation

• Principal component analysis integrating multiple response variables

 

 

DISCUSSION

Lines 657-669: The discussion mentions phytochromes, cryptochromes, and phototropins but fails to:

• Explain specific signaling cascades triggered by spectrum conversion
• Connect photoreceptor activation to observed morphological changes
• Address photoreceptor crosstalk under simultaneous red and blue light conversion
• Discuss fluence rate thresholds for photoreceptor activation under films

Missing critical explanation: How does passive spectrum conversion (maintaining total PPFD) trigger the same responses as supplemental lighting studies cited?

2. Fundamental Energy Balance Error

Lines 662-668: The biomass increase claims violate basic photosynthetic principles:

• No acknowledgment of energy conservation laws: Spectrum conversion cannot increase total photon flux
• Missing quantum efficiency discussion: Down-conversion inherently involves energy losses (Stokes shift)
• Absent light transmission analysis: Films inevitably reduce total light transmission
• No photosynthetic efficiency calculations: How can reduced photon flux increase biomass?

INADEQUATE LITERATURE INTEGRATION

1. Inappropriate Technology Comparisons

Lines 672-678: Comparing LED studies to passive film conversion is scientifically questionable:

• Different light delivery mechanisms: Point sources vs. diffuse conversion
• Temporal light patterns: Continuous vs. supplemental lighting regimes
• Energy input differences: Additional vs. converted photons
• Spectral purity variations: Narrow-band LEDs vs. broad-band conversion

2. Missing Commercial Reality Assessment

Lines 645-647: Claims about "promising applications" lack:

• Economic feasibility analysis: Cost per converted photon vs. LED alternatives
• Energy efficiency comparisons: Conversion losses vs. direct LED efficiency
• Durability considerations: Film degradation under agricultural conditions
• Scalability challenges: Research tunnels vs. commercial greenhouse implementation

Lines 697-722:

• Contradictory results unexplained: Pink film reduces Pn but maintains chlorophyll - no mechanistic explanation
• Missing light saturation analysis: No discussion of whether plants were light-limited
• Absent stomatal mechanism discussion: No explanation for gs changes under spectrum conversion
• Ignored VPD effects: Films alter microclimate affecting transpiration

2. Anatomical Response Oversimplification

Lines 688-696: The leaf anatomy discussion lacks depth:

• No chloroplast density analysis: Missing explanation for chlorophyll increases
• Absent light penetration modeling: No discussion of how anatomy affects light distribution
• Missing developmental timing: No consideration of leaf age effects on spectrum responses
• Ignored mesophyll conductance: No discussion of CO₂ diffusion pathway changes

Lines 753-803: The postharvest discussion lacks mechanistic foundation:

• No pre-harvest programming explanation: How do light treatments affect fruit physiology?
• Missing bioactive compound biosynthesis pathways: No discussion of phenylpropanoid regulation
• Absent cell wall metabolism discussion: No explanation for texture/firmness changes
• Ignored respiratory metabolism: No discussion of storage respiration patterns

2. Scale-Up and Commercial Viability

Entirely missing discussion of:

• Energy return on investment: Conversion efficiency vs. agricultural benefit
• Regional applicability: How do results translate across different latitudes/climates?
• Seasonal interactions: How do treatments interact with natural photoperiod changes?
• Cultivar specificity: Are responses universal across V. corymbosum cultivars?

FUNDAMENTAL STRUCTURAL PROBLEMS

1. Results-Discussion Disconnect

• Unexplained contradictions: Results show decreased Pn but discussion claims improved photosynthesis
• Ignored experimental limitations: No acknowledgment of single tunnel per treatment

2. Literature Gap Analysis Failures

Missing discussions of:

• Photoselective net research: Extensive literature on colored nets in berry production ignored
• Quantum dot technology: No discussion of conversion mechanism efficiency
• Controlled environment optimization: Missing integration with greenhouse climate control literature

 

 

CONCLUSIONS

1. Complete Absence of Experimental Limitations

The conclusions critically fail to acknowledge:

• Single tunnel per treatment: Fundamental pseudoreplication rendering statistics meaningless
• Single growing season: No temporal validation or seasonal interaction analysis
• Single cultivar testing: No genetic diversity assessment for treatment responses
• Controlled environment limitations: No scalability analysis to commercial production systems
• Missing environmental interactions: No consideration of latitude, climate, or regional applicability

2. Ignored Technical Constraints

Missing critical discussions:

• Film degradation rates: No mention of spectral conversion stability over time
• Maintenance requirements: No consideration of cleaning, replacement, or durability issues
• Energy efficiency analysis: No comparison of passive conversion vs. LED alternatives
• Installation complexity: No assessment of practical implementation challenges

3. Unrealistic Market Implementation Claims

Lines 814-817: The suggestion of "high commercial value among retailers" is entirely speculative:

• No economic modeling: Missing cost-per-kilogram analysis for film implementation
• Ignored supply chain complexity: No analysis of postharvest handling modifications needed

SUGGESTED CONCLUSION CORRECTIONS

1. Replace Overstated Claims with Data-Supported Statements

Current problematic statement: "Red film positively influences the growth and development of vegetative biomass" Required correction: "Under controlled tunnel conditions with single-season evaluation, Red spectrum-conversion films showed increased plant biomass, though this requires validation through multi-season studies with proper experimental replication before commercial recommendation."

2. Add Essential Limitation Acknowledgments

Insert mandatory limitations section: "Several critical limitations constrain the applicability of these findings: (1) Single tunnel per treatment precludes definitive statistical conclusions; (2) Single-season data cannot predict consistent performance across varying environmental conditions; (3) Energy balance analysis is needed to determine net photosynthetic benefit; (4) Economic feasibility requires comprehensive cost-benefit analysis including film procurement, installation, and maintenance costs; (5) Scalability to commercial greenhouse operations remains unvalidated."

3. Provide Realistic Commercial Assessment

Replace speculative commercial claims with: "While initial results suggest potential benefits of spectrum-conversion technology in berry production, commercial implementation requires: (1) Multi-year validation studies across diverse growing conditions; (2) Comprehensive economic analysis comparing costs with LED alternatives; (3) Consumer acceptance testing for spectrum-modified fruit; (4) Development of industry standards for film installation and maintenance; (5) Regulatory approval processes for novel cultivation technologies."

4. Include Required Future Research Directions

Add essential research recommendations: "Future research priorities include: (1) Proper experimental design with multiple tunnel replication; (2) Multi-cultivar and multi-season validation studies; (3) Molecular analysis of photoreceptor pathway activation; (4) Economic modeling for commercial feasibility; (5) Life-cycle assessment of film technology vs. LED alternatives; (6) Consumer preference evaluation for spectrum-modified fruit products."

 

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Author Response

we are thankful to the referee for the comment on our manuscript

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Authors studied the impact of films on growth, yield and postharvest quality of blueberry, the structure is clear and the experiment arranged well. However, the originality idea of the topics is not very clear. To further improve this manuscript, I have the following suggestions:

1, Not only the light spectral but the light intensity is also import to the growth of plants, please add the information about the light intensity of inside each treatment in 2, Materials and Methods.

2, In 2.3 section, the micro-morphological measurements of leaf were discussed. Due to eh dry matter percentage is related with the amount of light interception in each treatment. How about the light interception in each treatment? According to the information in Table2，the leaf area is different in each treatment, the light interception should be quite different.

3, In Line 492 the Table 1 should be table 5.

4, Considering the Integrity of this study, in the discussion, the light use efficient should be added due to the yield of blueberry was discussed in the experiment.

Author Response

Authors studied the impact of films on growth, yield and postharvest quality of blueberry, the structure is clear and the experiment arranged well. However, the originality idea of the topics is not very clear. To further improve this manuscript, I have the following suggestions:

1, Not only the light spectral but the light intensity is also import to the growth of plants, please add the information about the light intensity of inside each treatment in 2, Materials and Methods.

Response: We thank the reviewer for the comment. The influence of light intensity is negligible since all four treatments were around ~1020 μmol m⁻² s⁻¹ on a full sunny day. We added this information to the manuscript.

2, In 2.3 section, the micro-morphological measurements of leaf were discussed. Due to eh dry matter percentage is related with the amount of light interception in each treatment. How about the light interception in each treatment? According to the information in Table2.the leaf area is different in each treatment, the light interception should be quite different.

Response: We thank the reviewer for the suggestion. The light interception depends on the leaf thickness, leaf area and leaf mass area (LMA). All the mentioned parameters were calculated; however significant differences were only found in leaf thickness and leaf area whereas reported below no differences were found in leaf mass area between the treatments.

	Cnt	Red	Pink	Blue
Leaf Mass Area (g/m2)	237.7 ± 11.81ns	216.2 ± 41.17ns	244.2 ± 32.19ns	217.5 ± 20.67ns

 

Due to these data, we think that the influence of the amount of light interception was not relevant respect to the influence of light spectral modulation. Indeed, the consideration of light interception was far from the scope of the manuscript and, after this consideration regarding LMA data, we decided to avoid the in-depth discussion related to these data in the manuscript.

3, In Line 492 the Table 1 should be table 5.

Response: We thank the reviewer for the comment. We corrected the table number in the manuscript.

4, Considering the Integrity of this study, in the discussion, the light use efficient should be added due to the yield of blueberry was discussed in the experiment.

Response: We thank the reviewer for the comment. Discussion points on light use efficiency were added to the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

"Experimental design" is a statistical term that describes how the trial was set up according to its statistical framework. It should include a definition of the experimental unit (individual poly tunnel), the number of treatments (3 + control), true replications (zero), subsamples (10 plants, which the authors refer to as "biological replicates") etc., plus how the experiment was arranged (e.g., completely randomized design, randomized complete block design, split-plot, etc.). This arrangement affects how the statistical analysis is conducted.

The fundamental problem with this study is that the treatments are not replicated, meaning no statistically robust comparisons of the treatments can be done. 

Accordingly, the work presented in this manuscript is not fit for publication in a peer-reviewed scientific journal. You may be able to report your results in something like a conference proceedings as a preliminary study.

Please refer to the following reference for further information on experimental design in plant science research:

Alistair Rogers, Karl-Josef Dietz, Miriam L Gifford, John E Lunn, The importance of independent replication of treatments in plant science, Journal of Experimental Botany, Volume 72, Issue 15, 28 July 2021, Pages 5270–5274, https://doi.org/10.1093/jxb/erab268

 

Author Response

"Experimental design" is a statistical term that describes how the trial was set up according to its statistical framework. It should include a definition of the experimental unit (individual poly tunnel), the number of treatments (3 + control), true replications (zero), subsamples (10 plants, which the authors refer to as "biological replicates") etc., plus how the experiment was arranged (e.g., completely randomized design, randomized complete block design, split-plot, etc.). This arrangement affects how the statistical analysis is conducted.

The fundamental problem with this study is that the treatments are not replicated, meaning no statistically robust comparisons of the treatments can be done.

Accordingly, the work presented in this manuscript is not fit for publication in a peer-reviewed scientific journal. You may be able to report your results in something like a conference proceedings as a preliminary study.

Please refer to the following reference for further information on experimental design in plant science research:

Alistair Rogers, Karl-Josef Dietz, Miriam L Gifford, John E Lunn, The importance of independent replication of treatments in plant science, Journal of Experimental Botany, Volume 72, Issue 15, 28 July 2021, Pages 5270–5274, https://doi.org/10.1093/jxb/erab268

Response: We thank the reviewer for all his/her suggestions and for specifying some basic concept about statistics. However, please consider that among the co-authorships there are scientists with a consolidated career and more than 150 publications each in top-rank journal. So, the abovementioned consideration seems a bit disrespectful to our team skills. Anyway, the referee should note for example that other works with the same experimental design and arrangement (listed below) have been already published in peer-reviewed journal passing all steps of revisions by scientific reviewers:

El Horri, H., Vitiello, M., Ceccanti, C., et al. (2024). Ultraviolet-to-blue light conversion film affects both leaf photosynthetic traits and fruit bioactive compound accumulation in Fragaria× ananassa. Agronomy, 14.

El Horri, H., Vitiello, M., Braca, et al. (2024). Blue and red light downconversion film application enhances plant photosynthetic performance and fruit productivity of Rubus fruticosus L. var. Loch Ness. Horticulturae, 10(10), 1046.

However, we took the referee point that idealistically one should have at least unit replications (therefore 3 growth chamber, 3 fields, 3 tunnels – for any treatment) but has the referee ever ask him/herself if it is really always possible and/or necessary? Have the majority of papers followed this kind of approach? For example, I consider some scientific manuscript by the authors suggested by the referee (Alistair Rogers, Karl-Josef Dietz, Miriam L Gifford, John E Lunn, The importance of independent replication of treatments in plant science, Journal of Experimental Botany, Volume 72, Issue 15, 28 July 2021, Pages 5270–5274, https://doi.org/10.1093/jxb/erab268) and for most of them the same multi-unit approach is missing. Just to show one example, this paper “Avidan O, Martins MCM, Feil R, Lohse M, Giorgi FM, Schlereth A, Lunn JE, Stitt M. Direct and indirect responses of the Arabidopsis transcriptome to an induced increase in trehalose 6-phosphate. Plant Physiol. 2024 Sep 2;196(1):409-431. doi: 10.1093/plphys/kiae196. PMID: 38593032; PMCID: PMC11376379” only consider a single growth chamber as experimental unit.

This consideration to say that of course the referee is right, and this kind of approach has to be followed when there is the possibility (lot of space, facilities, etc…) or when there are some uncontrolled conditions that require to have multiple units. But practically, when the experimental design allows to get uniform results along with the single experimental unit (so, suggesting no gradient, variations, etc.) I cannot find any mistakes or limitations, as for the previous manuscript by Avidan et al. 2024, which is an excellent paper. Therefore, I would kindly ask the referee be honest and aware about possible limitations in research space and facilities, till when this kind of approach leads to wrong/misleading results. I think it’s not the case.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The author has revised all the questions.

Author Response

The author has revised all the questions.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

All questions and requests were satisfactorily answered and incorporated by the authors. The modifications that were not made were adequately justified.

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Reviewer 4 Report

Comments and Suggestions for Authors I think the manuscript has been sufficiently improved to warrant publication in Agronomy.

Author Response

I think the manuscript has been sufficiently improved to warrant publication in Agronomy.

Response: we are thankful to the referee for her/his comments on our manuscript

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

In the peer review process, I believe submitted works should be evaluated objectively according to their own individual merits. The authors’ publishing histories and professional achievements should therefore be immaterial to an unbiased peer review. 

The authors appear to finally acknowledge (some of) the experimental design limitations of their study. However, their responses do not address the fundamental issues with this study, which were already mentioned, nor the flaws in the statistical analyses and interpretation of the results.

It is my understanding that there are 4 experimental units (individual tunnels, although their independence is questionable given their relative proximity, referencing the images in Figure 1), 4 treatments (poly coverings), and no replications of those treatments. Therefore, data cannot be statistically analyzed, nor the results presented, as if there had been true replications of the treatments. In light of this, the statistical significances assigned to the treatments in majority of the presented results are misleading at best. 

 

 

Author Response

In the peer review process, I believe submitted works should be evaluated objectively according to their own individual merits. The authors’ publishing histories and professional achievements should therefore be immaterial to an unbiased peer review. 

The authors appear to finally acknowledge (some of) the experimental design limitations of their study. However, their responses do not address the fundamental issues with this study, which were already mentioned, nor the flaws in the statistical analyses and interpretation of the results.

It is my understanding that there are 4 experimental units (individual tunnels, although their independence is questionable given their relative proximity, referencing the images in Figure 1), 4 treatments (poly coverings), and no replications of those treatments. Therefore, data cannot be statistically analyzed, nor the results presented, as if there had been true replications of the treatments. In light of this, the statistical significances assigned to the treatments in majority of the presented results are misleading at best. 

 

Answer: Our publicatory history is not just to show our prestige but to let the referee know that in previous works following similar experimental designs (and in this actually given that other two referees found our work suitable for publication without statistic problems) we did not receive any comments related to the statistic interpretation of our data, meaning that our procedure is not incorrect. Basically, maybe I was not clear in my explanation.

The number of experimental unit is not 4; we only have one experimental unit (according to their definition) each one represented by a different coloured tunnel. Of course the problem was the spece to get a replication of these tunnels. But we would like drive the attention of the reader to the fact that inside there are 10 biological samples (10 - plants) which are indipendent (each plant per pot) and uniform (we moved the plants inside the tunnels every 3 days to avoid confounding effects of the environmental condition, which however are uniform in terms of RH and °T as shown by our datalogger). So, what's wrong? The experimental design is as follows:

1) One experimental unit per treatment

2) 4 treatments (4 colored tunnels) 

3) 10 biological replicates inside each treatment

So, at least it might be arguable the lack of replication of experimental units, but as I commented in my previous report, one of the co-author of the review sugegsted by the referee followed, in a research paper, a similar approach having only a single growth chamber with different treatment inside. In my opinion that is completely understandable, especially when you can minimize the errors (datalogger show uniform RH and °T in each tunnel and the irrigation system is centralized for all the tunnels, thereby avoiding treatment-related problems). 

In conclusion, we appreciated the constructive dialoge with the referee but we do not find any error in our experimental design. This is our last reply to the referee because we have no further explanation to provide.