The Effect of Light Intensity on the Photosynthetic Parameters of Tomato Rootstocks

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript provides generally clear results on the responses of different rootstock cultivars to PPFD. However, many details about materials and method, particularly experimental design, have not been provided. The type of graph used to present the data is inappropriate. Furthermore, there is the question of whether the measured parameters and results in the study are practically relevant to the stated objective, while several other more relevant parameters have not been investigated. There are also some wording and grammatical mistakes that should be corrected. Detailed comments are provided below.

1. In the introduction, the authors state that the objective of the study "was to assess the impact of light intensity on the quality of various tomato rootstocks." However, quality of rootstocks is associated with grafting ability, not growth per se. Better rootstock growth doesn't always translate to better grafting. Leaf area and leaf number are mostly irrelevant for rootstocks, as their shoots will be cut off. Large stem diameter can actually lead to mismatch with scions and failure of grafts, as well as development of secondary growth and lignification of the stem, making it harder for grafts to heal. The authors should consider investigating aspects that are more related to grafting ability of the rootstocks, such as stem structure, root carbohydrate accumulation, root pressure, etc.
2. Line 75–76: What are "Sakata" and "ESASEM"? Companies? Institutes? Please provide more details.
3. Please state specifically how many replications there were, and how many plants were grown/selected/measured/etc. per replication, not per treatment.
4. Line 84–86: "18 days after sowing, when the plants had an average of 3 - 4 true leaves (grafting size), 15 randomly selected plants from each treatment were 85 used for measurements." This should be moved to section 2.2.
5. Line 89: please be more specific about the amount of water the plants received. Different PPFDs can lead to different transpirations and water consumptions. How was this addressed?
6. Please provide the experimental design (CRD, RCBD, etc.), and how the replications were arranged in the chambers in practice.
7. Line 92: The DLIs don't match the PPFDs. Unit for DLI is incorrect (mol^–2 d^–1, not m^–2 d^–1 per 16 h).
8. Line 93: When was the PPFD measured? One time before the experiment, or continuously adjusted during the experiment as the plants grew?
9. Line 94: What is "plant level"? At the shoot tip?
10. Please provide information about the lamps used in the experiment (type, producer, etc.).
11. For 18-day old tomato seedlings, the root dry weight is very small. Scales of 0.001-g accuracy would give a lot of measurement errors.
12. Line 107: "5 plants per treatment" per replication?
13. When were the leaf gas exchange and chlorophyll fluorescence indices measured? On day 18 as well? If to assess the effect of PPFD on rootstock growth, these indices should be measured days before. Measurements on day 18 would be irrelevant, as in production, the rootstocks would be grated at this point, and their shoots cut off, therefore any state of the leaves (photosynthetic rate, quantum yield, stress level, etc.) at this point is of no concern to the rootstocks. It is more interesting to learn about, for example, the state of the leaves on day 10–11, which would be relevant to the growth of the rootstocks from day 11–18, and which could be very different from the state of the leaves on day 18.
14. Tomato leaves are notoriously difficult to measure for photosynthetic rate using leaf chamber, especially when they are small, due to the lobed shape and curvature of the leaves. How was this addressed during the measurement?
15. Line 114: "3 plants per treatment" per replication?
16. Line 117: Please indicate the PPFD used for light adaptation.
17. Line 121–123: "Before measurement... from the dark." This is repetitive and unnecessary, and can be omitted.
18. Line 153: This section states the post-hoc test used was Tukey, but in Table 1 and 2, it is stated "LSD – Fisher’s protected least".
19. Line 159–163: Please remove.
20. Line 172–173: "Consequently, these rootstocks are deemed more suitable for grafting purposes." It is inappropriate to deem so without further investigation. Stem diameter too large can actually cause mismatch with scions and be detrimental to grafts. The authors should conduct testing on actual grafting success rate of the seedlings in each treatment with a common scion.
21. Line 173: Please add unit after "150".
22. Line 184–185: "...rootstocks grown under lower light intensities exhibited enhanced dry matter accumulation in their roots." This statement is not concrete. Increased root DW/FW ratio could be the result of reduction in shoot growth, not increase in root growth per se.
23. Table 1: Please provide data of fresh and dry weights of shoots and roots. Fresh and dry weights are the most important indicators of growth, and should be presented.
24. In the Materials and Methods, it is stated that gas exchanged indices "were measured on the third developed leaf..." (Line 111). However, there were treatments that only had 2 leaves (Goldrake-150 and TOR23901-150). How about these plants?
25. Photosynthetic rate doesn't seem to translate very well to growth (height, leaf area, stem diameter) for TOR23901 cultivar, as the cultivar has very low results for these growth parameters, even though photosynthetic rate is comparable between this cultivar and the others. Is there any explanation for this?
26. The x-axes of the graphs in Fig. 2, 3 and 4 do not scale appropriately. 0–1 has the same distance as 1–11. This will skew the data presented. On a related note, why were these peculiar PPFDs of actinic light selected to measure chlorophyll fluorescence indices instead of rounded numbers that match the growing PPFDs?
27. Why nonphotochemical quenching of Auroch cultivar under different PPFDs differed significantly at 1251 μmol m^–2 s^–1 (Fig. 2A), but the effective quantum yield did not (Fig. 3A)?
28. Fig. 3: Why did the Y(II) show a strange increase at 536–701 μmol m^–2 s^–1 of actinic light
29. Please add unit for ETR in Fig. 4.
30. Please recheck the data of Fig. 3 and 4, as some data don't seem to match each other. For example, for cultivar 'Auroch', Y(II) at actinic light of 11 μmol m^–2 s^–1 is about 0.6 for all treatments (Fig. 3A). Following equation (3) (line 142), this should translate to ETR of about 2.8. But in Fig. 4A, the ETR at this actinic light level seems to be above 4. Similarly for actinic light of 21 μmol m^–2 s^–1, with Y(II) of around 5, ETR should be around 4.4, not matching Fig. 4A.
31. Please change the color of Goldrake and 350 treatments in Fig. 5A and B, respectively, as they are too similar to Ficus and 250 treatments. The text in the graphs of Fig. 5 should also be adjusted to avoid overlapping too much.
32. Based on Table 3, the F1 axis can be called the growth axis. What about F2 axis? What does this axis represent?
33. The factor loadings of PCA in Table 3 exclude data about chlorophyll fluorescence indices (NPQ, Y(II), ETR). Is there a way we can incorporate these data as well?
34. The authors discussed and concluded in the Discussion that PPFD of 250 μmol m^–2 s^–1 is optimal for growing tomato rootstocks. However, this is not concretely backed up by the data, as according to Fig 5B, treatment 250 and 350 are quite spread out and overlapping each other. One can only conclude that 150 μmol m^–2 s^–1 is worse than the other two (on principal component F1 alone), but cannot say which one between 250 and 350 μmol m^–2 s^–1 is better.

Comments on the Quality of English Language

The authors should recheck errors in English writing, or utilize English editing services to proofread the manuscript. Below are examples of some mistakes.

1. Line 42: "...have been successfully exercised achieved"
2. Line 43: "...can boost be boosted".
3. Line 74: "...with a 16 h thermoperiod and a photoperiod was maintained."
4. Line 76–78: "‘Goldrake’ – well-known commercial... winter-planting cycles." This is not a sentence.
5. Line 78: "‘Ficus’ – is also a well-known high vigor rootstock, is perfect for medium- and long-cycle cultivation, used for increased yield potential, especially for long-cycle cultivation"
6. Line 87: "...were N, 110; P2O5, 50; K2O, 160 with sufficient/adequate/etc. microelements Fe, Mn,..."
7. Line 90–91: "The plants were cultivated from sowing to 18 days under three different lighting Photosynthetic Photon Flux Density (PPFD) levels: from sowing for 18 days:"
8. Line 165: "The growth of rootstocks and their biometric indicators is are..."
9. Line 181: "...except ‘TOR23901’, demonstrating which demonstrated the least accumulation..."
10. Table 1: "Leave Leaf area"

Author Response

Thank you for your sincere and thorough feedback. We have worked diligently to address all your comments and make the necessary corrections to the manuscript. Your insights have greatly improved its quality. We have included all our responses in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This is an experimental paper investigating the effects of light intensity on the photosynthetic system of tomato rootstocks, which has certain practical application value. The research design is relatively sound and the data are adequate; however, there are areas that need improvement in terms of writing conventions, methodological details, data presentation, and depth of discussion.

1. There is an inconsistency in the reported data: the experimental design included only three light intensity treatments (150, 250, and 350 µmol m⁻² s⁻¹), but four DLI values were listed in the manuscript. The authors should clarify the reason for this mismatch.

2. While the study provides valuable physiological data, it does not adequately address the molecular mechanisms underlying light intensity effects on plant growth, nor does it include a detailed analysis of light stress responses. It is strongly recommended that the authors expand the discussion to include these important aspects.

3. The sample sizes used in this study are relatively small and may limit statistical power. It is recommended that the authors increase the sample size. Furthermore, different sample sizes were employed for different measurements (n=5 for morphological parameters, n=3 for gas exchange and chlorophyll fluorescence), and the authors should provide clear justification for this inconsistency in the text.

4. The reference format is inconsistent and must be revised strictly according to the guidelines of Agronomy.

Author Response

Thank you for your sincere and thorough feedback. We have worked diligently to address all your comments and make the necessary corrections to the manuscript. Your insights have greatly improved its quality. We have included all our responses in the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Abstract

It lacks experimental design information, and it is not clear whether the lighting were supplemental or not. The results are mentioned as optimum light at 250 but also informed inconsistent growth effects with higher light intensities. The conclusion sentence about energy expenditure is based on the data facts or just the assumptions, it needs to be clear.

Overall, abstract is informative.

Introduction

It is informative.

Is the average yield mentioned worldwide or specific to some area?

Might need more literature review or mention previous works on light intensity and grafting work. It is not clear why lighting is needed? Is it due to weather or any other reason? Is there enough lighting in the region of experiment. There is background information about this. Objective of the study needs to be specific rather than general.

Materials and methods

Please check DLI values seems incorrect to me “The plants were cultivated under three different lighting Photosynthetic Photon Flux 90 Density (PPFD) levels: from sowing for 18 days: 150, 250, and 350 ± 10 µmol m⁻² s⁻¹, consti- 91 tuting daily light integrals (DLIs) of 8.64, 11.52, 14.4, and 17.28 430 m−2d−1 per 16 h, respec- 92 tively, starting from the sowing stage (Fig.1)”

It is not clear whether lighting source is supplemental or sole.

Table might be best for description about rootstock characteristics.

Why for gas exchange 1000 PPFD was used? Isn’t this different conditions to the PPFD used for growing?

Two way Anova is mentioned but factors are not included in the statistical analysis.

Results

The part that belongs to discussion is also included in result section.

Table 1 in the heading is written leave area . It should be leaf area.

PCA analysis does not provide different interpretations from previous table. Explanations are repetitive so might need to include only standout results that make more meaningful impacts on the manuscript. The Figure % is very crowdy and not clear what they are trying to show.

Discussion

It is too lengthy and repetitive use of same concept that medium light intensities being optimal.

It looks just like literature review in some sections drifting aways from main study and result explanations.

Statements about reduced leaf area due to photostress should be mentioned only is damage assessments were done in the study.

Conclusion

It generalizes the concept that 250 is best but some rootstocks performed better at higher light intensity so may change the sentence like light intensity demand varies according to rootstocks.

The reference to “increased energy efficiency” at 250 µmol m⁻² s⁻¹ is not quantified or analyzed in the study. There is no acknowledgement about limitation of the study and future research needs in the conclusion section.

 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The manuscript is understandable overall, but the English requires substantial editing for clarity, grammar, and sentence structure. Several sentences are overly long and repetitive.

Author Response

Thank you for your sincere and thorough feedback. We have worked diligently to address all your comments and make the necessary corrections to the manuscript. Your insights have greatly improved its quality. We have included all our responses in the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The authors investigated the effect of light intensity on the photosynthetic parameters of tomato rootstocks, which is of some interest. However, similar work has already been reported quite extensively in tomato and other vegetable crops. At present, the authors have not clearly articulated the distinctive scientific question and the substantive novelty of this study relative to the existing literature. I recommend that the authors make a stronger effort to highlight the specific contributions and novel aspects of this work.

 

Lines 38–39: The construction “was considered … and allows …” contains inconsistent verb tenses.

 

Lines 62–66: Studies of this type are not rare. The authors should discuss in more depth the core “knowledge gap” that motivates the overall research hypothesis, and explain more clearly what specific question is still unresolved.

 

Lines 73–74: The wording is difficult to understand.

 

Lines 74–82: Please clarify whether the four rootstocks used in the experiment are Solanum lycopersicum cultivars or interspecific hybrid rootstocks.

 

Lines 90–94: This passage is very confusing. PPFD is described at three levels, but four DLI values are reported, and “430 m−2 d−1 per 16 h” is unclear and appears to be an incorrect or incomplete unit. Please carefully check and correct the text.

 

Line 95: “grow” should be “growth.”

 

Line 100: The description of leaf area measurements lacks important detail. Does the measured leaf area include cotyledons, or only fully expanded functional leaves?

 

Lines 159–163: What is this section? It appears to be unrelated to the content of this manuscript.

 

Line 172: The Results section states “Consequently, these rootstocks are deemed more suitable for grafting purposes.” This is a typical over-interpretation. You only measured seedling growth and photosynthetic parameters 18 days after sowing, without any data on grafting success, scion growth, or yield. Therefore, the conclusion that these rootstocks are “more suitable for grafting” is not strictly supported by the data.

 

Line 310: Please clarify what exactly is meant by “greater stability” here.

 

In the Discussion section, the authors should more clearly and explicitly highlight the genuine novel aspects of this study, and structure the discussion around these points with a more mechanistic interpretation. At present, the Discussion mainly repeats previously published light-intensity thresholds and general conclusions from the literature, without sufficiently emphasizing what is new in this work.

Author Response

Thank you for your sincere and thorough feedback. We have worked diligently to address all your comments and make the necessary corrections to the manuscript. Your insights have greatly improved its quality. We have included all our responses in the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

• Comment 4: We think there is a misunderstanding.

What we suggested was that line 92–94 ("18 days after 92 sowing, when the plants... each treatment were used for measurements.") should be moved to Section 2.2, as it is about measurement.

Line 100–107 ("The plants were cultivated from sowing to 18 days... during rootstock grow.") should remain in Section 2.1, as it is about experimental design.

• Comment 26: Please use straight lines to connect between the data points in the graphs (Fig. 2, 3, 4). Do not use smooth lines unless they're calculated by regression.
• Comment 31: The colors in Fig. 5a and b have not changed. We recommend using another color, like purple, for Goldrake and 350 treatments to distinguish them from Fiscus and 250 treatments, respectively. Alternatively, the authors can use a different symbol (e.g. triangle).
• Comment 33: We think it is possible to include chlorophyll fluorescence data into the PCA, by simply choosing only the data at the actinic light PPFD corresponding to the growth PPFD of the treatment (e.g., 250 μmol⋅m⁻²⋅s⁻¹ for treatment 250). These would represent the chlorophyll fluorescence state of the plants in their growing condition.

Comments on the Quality of English Language

Line 382-384: "Meanwhile, the photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr), according to literature, significantly increase with increasing light intensity [24,30,31]."

Line 392-394: "Light of medium intensities Medium PPFD reduces excessive transpiration and water loss, ensuring better water use efficiency and stable Pn [32,33]."

Line 394: "The most significant differences in transpiration intensity rate among rootstocks..."

Line 403: "...any significant increases in rootstocks photosynthetic rate..."

Line 453: "These rootstocks The photosynthetic systems of these rootstocks worked very..."

Author Response

Once again, we thank you for your very valuable comments and suggestions, which we will certainly use in our further development. The attached file contains responses to your last comments. We hope that we managed to respond to all comments appropriately and that the quality of the manuscript is only improving.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you very much for your meticulous revisions. I believe this version is now ready for publication.

Author Response

We are very grateful for your comments and suggestions. Thanks to you, not only has the quality of the manuscript improved, but we have also improved with each comment.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have addressed my questions, and I have no further comments.

Author Response

We are very grateful for your comments and suggestions. Thanks to you, not only has the quality of the manuscript improved, but we have also improved with each comment.