The Growth and Development of ‘Mini Chal’ Tomato Plug Seedlings Grown under Various Wavelengths Using Light Emitting Diodes
Round 1
Reviewer 1 Report
The manuscript by Kim and Hwang presents some thorough research into the effects of several light spectra on growth and related parameters in young tomato seedlings. While not being very innovative, the study is well-designed, executed and described. I have some major and minor comments, however, that I would like to see addressed before the paper can be accepted.
Major comments
- the presentation of the results is more confusing than would be necessary. Namely, the authors name 3 control, and show them disconnected from the treatment groups these controls belong to. If the authors treated the results as a summary of three separate experiments (G light, UV-A light and FR light), they would be much easier to understand.
- in Table 2, the authors present the intensity within given wavelength ranges. They should add a column that shows the PAR (400-700 nm) for each treatment, as this makes it possible for the reader to easily see whether the amount of light the plants could use for photosynthesis was comparable between treatments. Within the Fr group, this does not seem to be the case - the authors should discuss what this might mean for their results
- the language of the article is mostly good, but lacking in places. The authors should have a critical look at the writing and, if necessary, ask a professional english editing service for help
Minor comments
l. 32: light is the most essential environmental factor - plants are photoautotrophs, after all!
l.33: maybe replace sugar by assimilate - more accurate
l. 35: photosynthetically
l. 38: unclear. How would blue light (or any light colour) affect the photoperiod? The photoperiod is simply the duration per day that plants see light - maybe the authors meant something different?
l. 39-40: the authors write that R light affects the photosynthetic rate. This is a very general statement! Any spectral band within the PAR range affects photosynthesis. The authors should be more precise
l. 43: is it at all surprising that growth under a given light colour is higher than in the dark?? I mean, this is to be expected isnt it?
l. 43-45: The authors could include a recent study by Kaiser et al., 2019, Scientia Horticulturae, which shows that G in a background of R/B increases growth of tomato under greenhouse conditions
l. 45: reported not reports
l. 57: remove of
l. 60-62: this is a good example for a sentence full of small english mistakes - please rephrase
l. 87: affected
l. 90: if this is chosen from a previous study, then the previous study should be cited
PPFD and PAR are used interchangeably - the authors should decide for consistent use of one of the two
l. 133: replace were by was
l. 161: reported not reports
l. 165-166: I dont think this is true for B light - B probably inhibits stem growth through signalling (receptors such as cytochromes), but not through its energy (what is that even supposed to mean?)
l. 167: what is [8] or [13] or [32-33] supposed to mean? This is shown in other parts of the MS as well, and I will not comment on it separately. It looks very strange - the authors should combine all references into one pair of brackets
l. 173: this is unclear - which plants are meant here?
l. 173: 'no studies have been conducted' - unclear what exactly is meant by that
l. 181-186: the authors could comment that in general, stem diameter was much less affected by treatments than stem height! What does that mean?
l. 191-192: bad english, please improve
l. 195: should be ' 21 days after start of treatment' - otherwise, this might be read as '21 days after end of treatment'. The same is true for some other figure captions
l. 221: it is thought that this response to UV-A is
l. 232-233: I have never heard about that - how does that work? Thicker leaves means higher capacity for water retention?
l. 246: remove the word logically
l. 257: SPAD does not directly indicate chlorophyll content, but often correlates with the actual Chlorophyll content - this should be rephrased to make it clear
l. 264: plants under R3B7
l. 267: these results were
l. 274: This is an example for an 'empty' sentence that doesnt convey any information by itself; the authors could easily omit it (and similar sentences elsewhere in the text) and simply refer to the figure or table when actually describing the results
l. 274-276: This sentence is so obvious that it doesnt make sense to write it! Of course, changes in fresh and dry weight are due to changes in growth! Change in biomass is literally the definition of growth! The authors should either remove the sentence or rephrase it
l. 280-281: heavier in stem fresh weight
l. 292: Previous research has defined
l. 295: I think the authors mean dry matter content here, which is something very different from dry matter
l. 299: these results indicated
Fig. 7A, y-axis caption: Should be try matter content, not dry natter
l. 315: This is wrong. A Fv/Fm value of more than 0.83 indicates that something went wrong with the measurement; 0.83 is probably the highest attainable value in a healthy leaf
l. 315: it is a very generalized comment to say that a high Fv/Fm value indicates that the plant is healthy! The authors should at least give 1-2 sentences of background information that actually convey what Fv/Fm indicates
l. 336: what is a gram plant? Maybe use latin name
Fig. 11: I dont see a reason to present the yields on trusses 1 and 2 separately. Please combine them and when discussing the results, have a look at which treatments actually produce statistically significant differences in yield
l. 381-382: This conclusion is wrong! The authors did not test any R/B ratios other than 30:70, so how can they state that 30:70 is the most effective?
Author Response
I am so grateful for the careful review of our research. Thanks to you, the quality of our paper is likely to improve. I answered your questions below. In addition, corrections were shown in red color in the manuscript.
Major comments
○ The presentation of the results is more confusing than would be necessary. Namely, the authors name 3 control, and show them disconnected from the treatment groups these controls belong to. If the authors treated the results as a summary of three separate experiments (G light, UV-A light and FR light), they would be much easier to understand.
- In order to clarify the results, a representative response of the seedlings by the treated light qualities was re-summarized. As a result, the responses of G, UV-A, and Fr to seedlings were similar compared to those of R3B7, which was the best in seedling quality, so I wrote them together. And the order of the conclusions was slightly modified. (Line 369-371)
○ In Table 2, the authors present the intensity within given wavelength ranges. They should add a column that shows the PAR (400-700 nm) for each treatment, as this makes it possible for the reader to easily see whether the amount of light the plants could use for photosynthesis was comparable between treatments. Within the Fr group, this does not seem to be the case - the authors should discuss what this might mean for their results
- The total light intensity was adjusted to 200 μmol·m-2·s-1 by using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy) measured by PPFD. Far-red is not included in photosynthetic active radiation. Therefore, in this table, it seems that the photosynthetic active radiation and fr are mixed and the calculation is wrong. Therefore, we did not present such a table like many other researches that have been studied using far-red, and only shown in Figure 1. We decided to delete the table without confusing the reader.
○ The language of the article is mostly good, but lacking in places. The authors should have a critical look at the writing and, if necessary, ask a professional english editing service for help
- Thank you very much for your review and for correcting any grammatical errors. The internal coauthor and three external experts who did not participate in the paper helped with the English proofreading work. After that, a professional paper English proofing company completed the paper revision work. Therefore, we will make up for faults by continuing to check this paper.
Minor comments
l. 32: light is the most essential environmental factor - plants are photoautotrophs, after all!
- The contents were revised by the contents that you mentioned, and ‘the light is the most important environmental factor’ and ‘plants are photoautotrophs’ are specified. (Line 31-32)
l.33: maybe replace sugar by assimilate - more accurate
- To be more precise, we replaced sugar with assimilation products. (Line 33)
l. 35: photosynthetically
- The photosynthetic has been modified to photosynthetically. (Line 34)
l. 38: unclear. How would blue light (or any light colour) affect the photoperiod? The photoperiod is simply the duration per day that plants see light - maybe the authors meant something different?
- We agreed with the reviewer and deleted the ‘photoperiod’ in order to balance the backward sentences described for red light. (Line 37)
l. 39-40: the authors write that R light affects the photosynthetic rate. This is a very general statement! Any spectral band within the PAR range affects photosynthesis. The authors should be more precise
- We agree with the reviewer's advice that it is a general condition that red light affects the rate of photosynthesis. Therefore, we have modified the ‘photosynthesis rate’ more specifically to 'have great potential for use as a light quality to drive photosynthesis'. (Line 38-39)
l. 43: is it at all surprising that growth under a given light colour is higher than in the dark?? I mean, this is to be expected isnt it?
- Since the only sentence "Arabidopsis thaliana seedlings grown under a combination of G, R, and B lights were taller than those grown under monochromatic R or B lights" following the sentence mentioned by the reviewer can be explained enough about the effect of G light on the plant, therefore the mentioned sentence by reviewer was deleted. (Line 41)
l. 43-45: The authors could include a recent study by Kaiser et al., 2019, Scientia Horticulturae, which shows that G in a background of R/B increases growth of tomato under greenhouse conditions
- I have added the contents of recent paper of Kaiser et al., 2019 on green light that you recommended. (Line 42-43)
l. 45: reported not reports
- 'reports' has been changed to 'reported'. (Line 43)
l. 57: remove of
- Please let me know once more what you want to remove and I will fix it.
l. 60-62: this is a good example for a sentence full of small english mistakes - please rephrase
- I have fixed some small mistakes. (Line 58-60)
l. 87: affected
- 'affects' has been changed to 'affected'. (Line 85)
l. 90: if this is chosen from a previous study, then the previous study should be cited
- The results of our previous research are submitted to a journal ‘Korean Society for Horticulture Science’ and recently accepted. But it has not been published yet. So we cannot know the exact information of the citations. This paper will show the cited documents during the review if the previous research papers have been published and the number of the books and papers can be known.
PPFD and PAR are used interchangeably - the authors should decide for consistent use of one of the two
- PAR was used only once in the whole context. PAR designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis, and PPFD is the photosynthetic photon flux density representing the luminosity units. Therefore, plant biologists quantify PAR using the number of photons in the 400-700 nm range received by a surface for a specified amount of time, or the Photosynthetic Photon Flux Density (PPFD). Therefore, PAR and PPFD have different meanings and cannot be unified into one.
Hall, David O.; Rao, Krishna (1999-06-24). Photosynthesis. Cambridge University Press. pp. 8–9. ISBN 9780521644976.
l. 133: replace were by was
- Because there are several subjects (position of flower clusters, flower cluster height, and fruit yields of first and second flower cluster), it seems to be appropriate to use plural verbs, so I left it as 'were'. If this is definitely wrong, let me know and I'll fix it.
l. 161: reported not reports
- 'reports' has been changed to 'reported'. (Line 149)
l. 165-166: I dont think this is true for B light - B probably inhibits stem growth through signalling (receptors such as cytochromes), but not through its energy (what is that even supposed to mean?)
- It was changed to explain that the elongation of the plant height is suppressed because of the signal, not the energy of blue light. (Line 153-155)
l. 167: what is [8] or [13] or [32-33] supposed to mean? This is shown in other parts of the MS as well, and I will not comment on it separately. It looks very strange - the authors should combine all references into one pair of brackets
- The agronomy template is supposed to be marked as above.
l. 173: this is unclear - which plants are meant here?
- I have specified some plants to make it clear as ‘in tomato plug seedling’. (Line 157)
l. 173: 'no studies have been conducted' - unclear what exactly is meant by that
- It means that there was no previous research related to this, but I deleted 'Although tomato plants seemed to have similar UV responses as these plants, previous studies related to this have not been conducted.' because it was not necessary.
l. 181-186: the authors could comment that in general, stem diameter was much less affected by treatments than stem height! What does that mean?
- As advised, we implied that elongation is more affected by light quality than growth in volume, and its meaning was mentioned. (Line 179-181)
l. 191-192: bad english, please improve
- The sentence was changed for improvement as ‘This result is considered to be due to the fact that the stem is thickened by the rapid growth of the plant by Fr.’. (Line 178-179)
l. 195: should be ' 21 days after start of treatment' - otherwise, this might be read as '21 days after end of treatment'. The same is true for some other figure captions
- All ‘21 days after treatment’ were changed as ‘21 days after start of treatment’.
l. 221: it is thought that this response to UV-A is
- We have changed the past verb to the current verb. (Line 210-211)
l. 232-233: I have never heard about that - how does that work? Thicker leaves means higher capacity for water retention?
- We cited the importance of leaf thickness by citing the following, and added a clarification to clarify. (Line 222-224)
‘Leaves are photosynthetic organs; thus, the shapes and sizes of leaves are very important factors influencing the success of plants. To absorb sufficient light energy, leaves must be as wide as possible. At the same time, to facilitate gas exchange (CO2, O2 and H2O), leaves must be as flat and thin as possible. However, if leaves are too wide and too thin, they will quickly become desiccated. Thus, leaf area and thickness are restricted by the availability of water in main.’
Tsukaya, H. Leaf shape: genetic controls and environmental factors. International J. Developmental Biol. 2004, 49, 547-555.
l. 246: remove the word logically
- We removed the word ‘logically’ in the sentence.
l. 257: SPAD does not directly indicate chlorophyll content, but often correlates with the actual Chlorophyll content - this should be rephrased to make it clear
- The content of 'SPAD value indicates chlorophyll content' was deleted, and it was changed to explain that SPAD value is related to chlorophyll content. (Line 249-250)
l. 264: plants under R3B7
- 'under' was inserted between plant and R3B7. (Line 257)
l. 267: these results were
- ‘was’ was changed into ‘were’. (Line 260)
l. 274: This is an example for an 'empty' sentence that doesnt convey any information by itself; the authors could easily omit it (and similar sentences elsewhere in the text) and simply refer to the figure or table when actually describing the results
- ‘The fresh and dry weights of ‘Mini Chal’ tomato leaves and stems are presented in Table 2.’ was deleted. And the notation for Table 2 has been moved elsewhere. (Line 268)
l. 274-276: This sentence is so obvious that it doesnt make sense to write it! Of course, changes in fresh and dry weight are due to changes in growth! Change in biomass is literally the definition of growth! The authors should either remove the sentence or rephrase it
- ‘The changes in the fresh and dry weights of leaves and stem in response to light treatments seem to be due to changes in the stem and leaf growth’ was deleted.
l. 280-281: heavier in stem fresh weight
- ‘fresh weight of stem’ was changed into ‘stem fresh weight’. (Line 271-272)
l. 292: Previous research has defined
- ‘Researcher defined’ was changed into ‘Previous research has defined’. (Line 283)
l. 295: I think the authors mean dry matter content here, which is something very different from dry matter
Fig. 7A, y-axis caption: Should be try matter content, not dry natter
- I agree with you that dry matter content is not dry matter, because it is the proportion of the dry weight in total fresh weight. Therefore, all ‘dry matter’ was changed into ‘dry matter content’.
l. 299: these results indicated
- ‘this’ was changed into ‘these’. (Line 291)
l. 315: This is wrong. A Fv/Fm value of more than 0.83 indicates that something went wrong with the measurement; 0.83 is probably the highest attainable value in a healthy leaf
- Removed "or greater" to indicate that it is only good up to 0.83. (Line 307)
l. 315: it is a very generalized comment to say that a high Fv/Fm value indicates that the plant is healthy! The authors should at least give 1-2 sentences of background information that actually convey what Fv/Fm indicates
- Several sentences have been added for background information of Fv/Fm. (Line 307-312)
l. 336: what is a gram plant? Maybe use latin name
- ‘green gram’ was changed into latin name as Vigna radiata L. Wilczek cv. KM-2. (Line 333)
Fig. 11: I dont see a reason to present the yields on trusses 1 and 2 separately. Please combine them and when discussing the results, have a look at which treatments actually produce statistically significant differences in yield
- Since the influence of light quality will disappear in later stages after transplanting, we wanted to clarify the difference in initial yields as affected by light qualities. Therefore, first and second flower clusters are represented separately. This is very important data because the initial yield in Republic of Korea is an important factor for farm income. If you do not mind, I would like to show the data separately.
l. 381-382: This conclusion is wrong! The authors did not test any R/B ratios other than 30:70, so how can they state that 30:70 is the most effective?
- I agreed to your advice and deleted the word that was most effective, and modified it to be more effective than other treatments. (Line 377)
Author Response File: 
Author Response.docx
Reviewer 2 Report
see the attachment.
Comments for author File: Comments.docx
Author Response
I am so grateful for the careful review of our research. Thanks to you, the quality of our paper is likely to improve. I answered your questions below. In addition, corrections were shown in green color in the manuscript.
It is widely accepted that PPFD (photosynthetic photon flux density) is defined as a photon flux density PFD) in the waveband of 400-700 nm and is expressed in the unit of mol m-2 s-1, while PAR (photosynthetically active radiation) flux density is a radiation flux density in unit of W m-2(or J m-2 s-1).
I agree with the reviewer's statement. So the table was deleted because it was judged wrong in Table 2, and only the figure 1 was shown like the other researches.
Lines 95-96: Does (“R:G:B=20:20 60 (G20)”) mean the ratio of photon flux density or radiation flux density? When R (650 nm):B (450 nm) is 100:100 in unit of photon flux density, the ratio in unit of radiation flux density ranges between 100:120 (=600/500) and 100:175 (=700/400). Thus, the unit needs to be shown clearly.
ratios are expressed in of Lines 95 as the ratio of the PFD of each light quality, and we added a description to Line 104-105.
Lines 96: Does ‘W m-1’ mean ‘W m-2’?
‘W m-1’ was changed into W m-2’ (Line 93)
In Table 2, the term PFD (photon flux density) should be used instead of PPFD, because PPFD is used only for PFD with waveband of 400-700 nm.
Thus, PFDs with waveband 300-399 and 700-799 are not included in PPFD (400-700 nm).
To prevent confusion for readers, we removed table 2 and modified all PPFDs in the content to PFD.
In Table 2, PPFD (400-700 nm) is 194.5 mol m-2 s-1 in FL treatment, but is 161 mol m-2 s-1in Fr1 treatment. In Table 2, PPFD ranges between 161 and 199 mol m-2 s-1, not 200 mol m-2 s-1.
The total light intensity was adjusted to 200 μmol·m-2·s-1 by using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy) measured by PPFD. Far-red is not included in photosynthetic active radiation. Therefore, in this table, it seems that the photosynthetic active radiation and fr are mixed and the calculation is wrong. Therefore, we did not present such a table like many other researches that have been studied using far-red, and only shown in Figure 1. We decided to delete the table without confusing the reader.
In the footnote of Table 2, “red:blue=30:70 +UV-A 0.8 W m-2”, Does “30:70” mean “30:70” in unit of photon flux density or radiation flux density? UV-A is expressed in unit of W m-2 (in unit of radiation flu density). In all the treatments, the same unit needs to be used ‘mol m-2 s-1’ or ‘W m-2’.
Since photosynthetically active radiation (PAR) and UV-A units cannot be the same, the phrase 'These ratios of the above light quality were expressed by PFD of each light quality' was inserted in materials and methods and Figure 1 to prevent confusion. (Line 95 and 104-105)
I am not sure if the authors can use a new term PAPFD (physiologically active photon flux density) with waveband 300-799 nm, which is almost 200 mol m-2 s-1 in all the treatments.
I tried to find a paper related to the PAPFD unit, but I could not find it. So the PAPFD unit is likely to be difficult to use. Thank you for your advice.
Does ‘Relative light intensity’ in vertical axis of Figure 1 mean ‘Relative photon flux density’ or ‘Relative radiation flux density’?
The light spectral distribution was measured using a spectroradiometer (ILT950, International Light Technologies Inc., Peabody, MA, USA) And the unit is mW/cm2/nm (Absolut irradiance) in the spectroradiometer. In the range of 300-800 nm, the highest value of light intensity measured in nm intervals was considered 100, then, other values of light quality are expressed as relative values based on 100. So the vertical axis is labeled ‘relative light intensity’.
Light intensity means either PFD or RFD (radiation flux density) (or luminous flux density in some cases). Thus, it is suggested not to use ‘light intensity’ to avoid the confusion in the manuscript, although the term ‘light quality’ can be used.
All light intensity was changed into PFD.
Line 74: what does a photometer measure? PPFD or PAR flux density or both?
We used two sensor using intensities of all light qualities. Therefore, methods of measuring the intensity of UV-A and far-red were added. (Line 71-73)
Line 90. Which papers in the ‘References’ discussed the light quality effects on tomato seedlings? Cite the papers specifically.
The results of the previous research are submitted to a journal ‘Horticultural Science and Technology (Korean Society for Horticulture Science)’ and recently accepted. But it has not been published yet. So we cannot know the exact information of the citations. This paper will show the cited documents during the review if the previous research papers have been published and the number of the books and papers can be known.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The photosynthetically photon flux density of PAR was measured and adjusted at the top of the plant once every three days using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy). UV-A and far-red intensity was measured using a spectroradiometer (ILT950, International Light Technologies Inc., Peabody, MA, USA).
In the above paragraph,
1) ‘Photosynthetically photon flux density’ should be changed to ‘photosynthetic photon flux density (PPFD)’, although the term ‘photosynthetically active radiation (PAR)’ is used. The unit of former is µmol·m-2·s-1 and the unit of latter is W m-2.
2) ‘UV-A and far-red intensity’ should be changed to ‘UV-A and far-red photon flux density (PFD)’, because the unit of µmol·m-2·s-1 is used in the ‘2.2. Light Quality Treatments’ section. The term ‘intensity’ should not be used because which unit was used to measure.
For example:
The photosynthetic photon flux density was measured and adjusted at the top of the plant once every three days using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy). UV-A and far-red PFD (µmol·m-2·s-1) was measured using a spectroradiometer (ILT950, International Light Technologies Inc., Peabody, MA, USA).
In ‘2.2. Light Quality Treatments’, the authors need to state clearly that the PPFD in 3 Fr treatments is about 20-40 µmol·m-2·s-1 lower than that in other treatments. Because this fact is essential to interpret the experimental results. And, this fact must be described again in ‘Result and Discussion’ section.
Author Response
Thank you for your review. We have responded to the comments, and the correction of the manuscript is marked in red.
The photosynthetically photon flux density of PAR was measured and adjusted at the top of the plant once every three days using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy). UV-A and far-red intensity was measured using a spectroradiometer (ILT950, International Light Technologies Inc., Peabody, MA, USA).
In the above paragraph,
1) ‘Photosynthetically photon flux density’ should be changed to ‘photosynthetic photon flux density (PPFD)’, although the term ‘photosynthetically active radiation (PAR)’ is used. The unit of former is µmol·m-2·s-1 and the unit of latter is W m-2.
2) ‘UV-A and far-red intensity’ should be changed to ‘UV-A and far-red photon flux density (PFD)’, because the unit of µmol·m-2·s-1 is used in the ‘2.2. Light Quality Treatments’ section. The term ‘intensity’ should not be used because which unit was used to measure.
For example:
The photosynthetic photon flux density was measured and adjusted at the top of the plant once every three days using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy). UV-A and far-red PFD (µmol·m-2·s-1) was measured using a spectroradiometer (ILT950, International Light Technologies Inc., Peabody, MA, USA).
‘Photosynthetically photon flux density’ was changed into ‘photosynthetic photon flux density (PPFD)’ and ‘UV-A and far-red intensity’ was changed into ‘UV-A and far-red PFD’. (Line 71 or 73)
In ‘2.2. Light Quality Treatments’, the authors need to state clearly that the PPFD in 3 Fr treatments is about 20-40 µmol·m-2·s-1 lower than that in other treatments. Because this fact is essential to interpret the experimental results. And, this fact must be described again in ‘Result and Discussion’ section.
We have already answered the similar question in the round 2 process. Please see the green paragraph below.
In Table 2, PPFD (400-700 nm) is 194.5 mol m-2 s-1 in FL treatment, but is 161 mol m-2 s-1in Fr1 treatment. In Table 2, PPFD ranges between 161 and 199 mol m-2 s-1, not 200 mol m-2 s-1.
The total light intensity was adjusted to 200 μmol·m-2·s-1 by using a photometer (HD2101.2, Delta Ohm SrL, Caselle, Italy) measured by PPFD. Far-red is not included in photosynthetic active radiation. Therefore, in this table, it seems that the photosynthetic active radiation and fr are mixed and the calculation is wrong. Therefore, we did not present such a table like many other researches that have been studied using far-red, and only shown in Figure 1. We decided to delete the table without confusing the reader.
The PPFD was adjusted to 200 μmol·m-2·s-1 with a photometer measuring the range of 400-700 nm. We added 'measuring the range of 400-700 nm wavelengths' to the text to avoid confusion. Also, the previous table showing the intensity of each wavelength was deleted because the calculations were wrong. Therefore, the total PPFD of 400-700 nm wavelengths was similar to 200 μmol·m-2·s-1 in all treatments, and UV-A and Fr PFD were separately added to it. We are sorry for the confusion.
Author Response File: Author Response.docx
