Can LED Lighting Be a Sustainable Solution for Producing Nutritionally Valuable Microgreens?

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper repots a study the effect of light spectrum on the content of specialized metabolites (SM) in broccoli, mustard, and garden cress microgreens grown under controlled conditions. Blue, red, and combination of blue and red spectrum (50:50) LED supplemental lighting was used, the morphological characteristics and the content of chlorophylls, polyphenolic compounds, and ascorbic acid were evaluated. Microgreens grown under the blue spectrum LED lighting had the highest content of ascorbic acid total phenolics and the highest antioxidant capacity. It can be concluded that optimal selection of the light wavelength has a positive effect on the final quality of the plant material, and LED supplemental lighting can be a sustainable and efficient method to produce microgreens of high nutrient quality with potential health benefits.

This paper is well written, and although not particularly original, it can be considered for publication in Horticulturae. However, in my opinion, some revisions and clarifications need to be made before its publication, as reported below.

Line 12:  It is very important also the light intensity, affecting physiological parameters of plants, omitting it makes the sentence inaccurate.

Line 15: Not only morphological parameters, also i.e. photosynthesis.

Line 86; Specify that plants of Brassicaceae family are widely used to microgreens production.

Line 91: Specify shortly the light recipe used for this work, and the experimental design.

Line 100: The description of randomized design could be reported after the light recipe description.

Line 117: The meaning of C and h° must be specified and described in the Methods as for a and b. greenness (a*), yellowness (b*) and lightness (L*), was used to calculate chroma (C) = (a*2+b*2)1/2) and Hue angle (H°) =  (b*/a*).?

Line 239: In plant material, the authors affirm that a complete randomized block was used for the experimental design. Moreover, three plant species and three light recipes were used. Then, in Statistical analysis, the authors affirm that One-Way ANOVA was used, but in the table the interaction between species and light wavelength was reported, and this can be obtainable with a factorial analysis. Clarify this misunderstanding.

Should randomized block analysis be considered?

For the statistical analysis was p 0.0001 only evaluated? If other values of p are considered must be indicated.

 Line 260-262 are more appropriate for Discussion section.

Line 263: you can specify that the interaction between factors plant species x light is not statistically significant.

 Table 2: The values of variance reported in Table 2 for chromaticity parameters are not significative for p ≤ 0.0001, (i.e. p =0.0076 or 0.0024). What was the p level for these values? Verify for all tables.

Line 286: perhaps and "in particular" in place of "while"

Line 290: as a interaction of factors.

Table 3: Insert p as: p ≤ 0...(Verify for all tables).

Table 4:  data reported are incomplete. Value ± se.

Table 5: data reported for some phenolic compounds are incomplete. Value ± se. Please verify.

Line 381: Is it possible to cite references more specific for Brassicaceae?

Line 446-448: This is the same concept reported in line 394-397.  It's a repetition that should be avoided.

Line 454-460: This description is more properly for the results than for discussion.

Review this sentence: something sounds wrong “Coumaric acid shows 98% higher concentration than in broccoli, and 77% than in garden cress”. Please verify.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Very interesting study and congratulations for i.

First of all, I have a general question: why did you choose to apply supplementary lighting in a plant growth chamber compared to a greenhouse for example; Τhe microgreens that will reach to the consumer come from growing in a growth chamber? I believe that in greenhouse cultivation the effect of supplemental led lighting, would give different results. I would like a comment on this.

line 11, "one of the most" is the correct phrase

Why you didn’t use a control treatment natural solar light?

line 399-400 "it is really surprising that these changes were not also expressed in the color of the leaves of the  species of microgreens studied". What explanation is there?

According to ABTS method, no significant differences were observed between three treatments. I believe that these results should get out of the paper.

Author Response

Please, find attached the anwers to your valuable comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript give us interesting idea, but it has some question need to be improved.

Abstract

1 Line11-18 The description of the background appears lengthy.

2 The result and conclusion are unclear.

Introduction

1 I suggest that authors cite the book of Microgreens. Novel Fresh and Functional Food to Explore all the Value of Biodiversity, but not the reference [15]. Because this reference did not give enough information. So, i hope authors check all references.

2 I suggest that authors should add more details to prove that how different lights affect the plant nutritional quality, such as Physico-chemical properties of microgreens, Specialized metabolites content, Individual phenolic content, Microgreens antioxidant activity etc, and give the logic relationship of all indexes. Otherwise, the novelty of your research cannot be proved.

3 why do you choose broccoli, mustard, and garden cress? Please explain it. Thank you.

So, from the introduction, reader cannot grasp the specific light how to affect the plant nutrients immediately. Meanwhile, The following research is more independent and cannot form a good logic with the introduction.

Methods

1 Could you supply the experiment time? What time choose the sample?and supply the picture of the samples.

Discussion and Conclusion

This part of the problem is similar to the introduction.There should be some relationship among all indexes. But the authors did not show reader progress in this regard. So there is no logic between each indicator results. 

Author Response

Please, find attached the anwers to your valuable comments.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The effect of light quality on the nutrition ingredients of microgreens was studied on three different species. The results showed that blue light had a positive effect on the accumulation of ascorbic acid and total phenols, while red light had a significant effect on the accumulation of chlorophylls and carotenoids, the pigments of photosynthesis. The research will be helpful to the better understanding of the effect of light wavelength on the microgreen quality and quantity, as well as the better application of LED technology to the vegetable industry.

However, some suggestions as follows:

1. The objective and the scientifc innovation of the study should be  emphasised clearly. Since there were so many litertures in the effects of light quality to the plants, the authors should find some aspects that the researchers did not or did not clearly demonstrated to carry out the experiments. At least, the authors did not clearly explain the  objective and the scientifc innovation of the study well.   

2. Experiment desgin: Why the experiment was desgined as blue, red and blue: red= 1:1?  How about the combined effects of blue and red lights in the prevoius studies? What the authors mostly concerned in this study that might provide the new ideas in comparsion to the prevoius studies? and why these three species were applied for experiments?

3. Results:  for the results of pigment and phenolic compounds, why some of them did not see the standard deviation? the authors should explain it and to make sure that the methods of statistical analysis is proper if there were missing data. Moreover,  since there were so many different index for the evaluation of the light quality effects, if it is possible to apply some  statistical methods for example the correlation analysis of the index to simplify the complex variations under the different treatments? Or maybe there were better statistical methods to reach the purpose what I suggest. 

4. Discussion and conclusion: I suggest the discussion should include the combined effect of blue and red. Moreover, the physiological index can be intensively explained by the molecular biology mechanism if possible. 

 

Comments on the Quality of English Language

I think the English language is pretty good since I am not native English expert. 

Author Response

Please, find attached the anwers to your valuable comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I always think that abstract of background is to long, please to simplify the refining. And the conclusion of abstract was mixed with significance. Meanwhile, the beginning of the conculsion is similiar with introduction.

The authors do not answer my question : Novel Fresh and Functional Food to Explore all the Value of Biodiversity, but not the reference [15]. Because this reference did not give enough information. So, i hope authors check all references.

Therefore, i hope authors to improved this paper.

 

 

Author Response

Respected,

please, find attached the answers to Your valuable comments.

Author Response File: Author Response.pdf