Photoperiod Modulates Morphophysiological Characteristics and Yield of Chia (Salvia hispanica L.) and Arugula (Eruca sativa L.) Microgreens Under Controlled Conditions

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Abstract: (1) The conclusion about "feasibility" and "income" in the last sentence appears abrupt in the abstract, lacking sufficient data support. Key quantitative results should be supplemented (such as "long photoperiod significantly increases leaf area and biomass"), and qualitative judgments such as "feasibility" and "income" that need to be discussed or concluded should be removed. (2) If TOPSIS is the core innovation point, please provide additional information on its purpose (comprehensive evaluation) and main findings (such as "6:18 PP has the highest comprehensive ranking, but 18:6 PP has more advantages in biomass output and economic benefits").
2. Introduction: (1) Insufficient elaboration on the background and necessity of Chia and Arugula research. Why choose these two? What special value do they have in the Microgreens market or nutrition? Provide additional information on the value (nutrition, market potential, etc.) of chia and arugula, and clarify the motivation for studying them. (2) The cited literature (such as Liu and Chu's research) illustrates that there are species differences and conflicting results in the impact of PP on Microgreens, but fails to further analyze the possible reasons for these contradictions (variety differences, light quality differences, measurement indicators differences, etc.), thus failing to highlight the significance of this study. (3) The three elements of light (light quality, light quantity, and light period) were mentioned, but this study only fixed the light quality (blue light) and light quantity (189.4 μ mol), without delving into why blue light was chosen and the rationality of studying PP under fixed light quantity (changes in PP essentially change the total light quantity). Additional explanation on the reasons for choosing a single blue light and a fixed light intensity (such as focusing on the PP effect to avoid interference from the interaction between light quality and quantity)? What is the special effect of blue light on morphological construction? ）Admit the limitations of this choice (total light quantity varies with PP). (4) The last paragraph supplements the innovation of this study, such as the first systematic evaluation of the PP response of these two species under blue LED and the integration of economic analysis.
3. Materials and Methods: (1) Fuzzy description of natural light (NL) processing (approximately 13-14 hours of light). There are significant differences between the spectrum and light intensity of NL (whether constant or daily average) and LED blue light. When using NL as one of the control groups, the lack or uncontrolled light environment parameters can lead to imprecise comparisons. The range of light intensity for NL processing (at least the mean) should be provided or its reference value as a "conventional production condition" should be explained. (2) The LED intensity is 189.4 μ mol · m ⁻² · s ⁻¹, but it is not specified whether it is the intensity at the canopy level or under the lamp. Clarifying the measurement location of light intensity is a crucial detail that directly affects the actual amount of light received by plants. (3) The calculation of Leaf Area Index (LAI) (Eq. 1) is based on sowing density (SD) rather than actual stand density. The actual density of surviving plants should be used to calculate LAI more accurately. (4) The calculation formula (Eq. 2) for "Partially Shaded Plants (PSP)" is unclear and the logic is questionable. The formula attempts to calculate the number of shaded plants based on sowing density (SD), unit area, and leaf area (LA). But 'plant units' are not defined, and whether this formula can accurately reflect the actual shading situation needs to be verified (such as whether the plant distribution is uniform?). The effectiveness and necessity of this indicator need to be demonstrated. (5) Chlorophyll and carotenoids were extracted using ethanol, following Lichtenhaler's (1987) formula, which was originally used for acetone extraction. The extinction coefficient of ethanol extract is different from that of acetone, and directly applying the formula may result in errors. It should be stated that the formula applicable to ethanol has been validated or used. (6) The cost calculation (Eq. 10) only considers the electricity cost (C) and does not include the depreciation cost, labor, substrate, and other operating costs of the LED lighting fixtures themselves. The conclusion of "revenue" and "feasibility" based solely on comparing electricity costs may be overly optimistic and incomplete. (7) The TOPSIS analysis flowchart (Fig 1) is too brief and does not specify which evaluation indicators were specifically used? And how to determine the weight of each indicator? Weight allocation is the key to TOPSIS and directly affects the results, requiring detailed explanation of the method (such as BWM input and consistency ratio).
4. Result: (1) Described the results of the hypocotyl length (HL) of chia, but there is a contradiction in the wording: "The longest hypocotyl is under low light (6:18, 12:12 PP)... Increasing light leads to a decrease in the length of the aerial portion (12:12, 18:6 PP). Here, "12:12" appears in both the "longest" group and the "reduced" group, with a confusing logic. Please carefully verify the data and analyze the results.
5. Discussion: (1) It is necessary to closely combine the results of this study with previous research (especially regarding species differences and contradictions in PP effects), and explain the reasons for the findings of this study (such as why long PP promotes Chia leaf area but inhibits hypocotyl elongation)? Why is arugula insensitive to PP? ）. (2) In depth discussion on the possible impact mechanisms of blue light on the physiology (such as chlorophyll synthesis, photoprotection) and morphology (such as shade avoidance response) of Microgreens under specific photoperiods. (3) Critical discussion on TOPSIS results: explain why the first ranked 6:18 (low energy consumption) is not as "feasible" as the second ranked 18:6 (high output) in the author's opinion? Is this judgment based purely on economic model outputs or combined with actual production experience (such as the possibility of long PP accelerating the growth cycle)? Clear explanation of the basis for judgment is required.
6. Conclusion: It should be refined, accurate, and in line with research objectives, highlighting the main findings (such as the selective effects of PP on different species and indicators), as well as the core results and recommendations of TOPSIS evaluation (such as recommending 18:6 PP as the optimal choice for balancing yield and cost). Clarify the limitations of this study, such as the use of a single blue light, fixed light intensity, failure to consider other costs, and incomplete comparability of NL controls.
7. There are some formatting errors in the manuscript (such as line confusion, suspected incomplete sentences), spelling errors (such as "mophysiological"), and undefined abbreviations (such as the first appearance of PP not indicating Photoperiod). Carefully proofread the entire text, correcting grammar, spelling, and formatting errors. Ensure that all charts are clear and self explanatory, with clear references and descriptions in the main text. Consider including detailed input data, weight calculation process, results, etc. of TOPSIS in supplementary materials.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Dear Reviewer 1.

We have carefully reviewed our article and incorporated all changes, adjustments, corrections, and improvements, taking reviewers' comments and suggestions into account. Therefore, we are resubmitting an improved version of our manuscript entitled “Photoperiod modulates morphophysiological characteristics and yield of chia (Salvia hispanica L.) and arugula (Eruca sativa L.) microgreens under controlled conditions”, with reference number horticulturae-4200327.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear editor,

I am writing to communicate my evaluation of the manuscript referenced Manuscript ID: Horticulturae-4200327, submitted for possible publication in Horticulturae.

The manuscript evaluates the impact of different blue LED light photoperiods, compared with natural light, on the growth and biomass production of Salvia hispanica and Eruca sativa cultivated indoors under controlled conditions. The authors focus on a set of agrophysiological and biochemical parameters related to plant growth and development.

Overall, the study addresses an interesting topic relevant to controlled-environment agriculture and microgreen production. However, the manuscript requires major revisions before it can be considered for publication.

I invite the authors to carefully address the comments and suggestions provided below, and to clearly highlight the revisions made in the manuscript and summarize them in the response letter to the reviewer.

ABSTRACT:

The abstract should be revised to more clearly highlight the most significant findings of the study. The authors are encouraged to report the key quantitative results and indicate their statistical significance (e.g., p-values) when presenting the main outcomes. This will help emphasize the scientific contribution and improve the clarity and impact of the abstract.

INTRODUCTION

The introduction is generally well structured and provides an adequate overview of the current state of the art related to the manuscript’s topic. However, I recommend that the authors clearly state the specific objectives of the study and explicitly formulate the research questions addressed in the manuscript. It would also strengthen the introduction if the authors present a clear hypothesis to support the research framework.

MATERIALS AND METHODS 

The authors are invited to provide more detailed information in this section, particularly:

Please justify the plant density used (160 g m⁻² for arugula and 120 g m⁻² for chia), especially since the study aims to analyze the effects of photoperiod and light conditions. The rationale for selecting these densities should be clarified.

The photoperiod treatments (18:6, 12:12, 6:18) should be written more clearly as Light/Dark (L/D) cycles, and the description should explicitly indicate which value corresponds to light and which to darkness.

The manuscript states that watering was performed three times daily using a manual sprayer with 100 mL of water per tray. Please indicate the basis for this irrigation regime (e.g., preliminary trials, substrate water-holding capacity). These details are essential to minimize the influence of external factors and ensure experimental reproducibility.

ADDITIONAL QUESTIONS:

1. The study focuses on blue LED light (450 nm), which is known to influence vegetative growth and stomatal regulation. However, what about the use of red LED light (660 nm), which is widely recognized for its role in photosynthetic efficiency and biomass production? Please justify the choice of light spectrum used in the experiment.
2. Do the authors consider 189 μmol.m⁻²·.s⁻¹ to be a moderate light intensity sufficient for vegetative growth under the experimental conditions? Please provide justification or reference.
3. The experiment lasted 12 days. Is this duration sufficient to obtain robust and conclusive results? The authors should justify the experimental duration, particularly in relation to microgreen growth stages.

RESULTS

• Table 2: Please verify the unit used to express yield (mg DW plant⁻¹). For example, the reported value 0.39 mg seems very low and should be checked.
• Table 2: Some results are presented without statistical grouping letters or standard deviations. Please clarify whether the reported values correspond to means, and include appropriate statistical information.
• Table 3: Please write DW (Dry Weight) in capital letters to standardize the abbreviation throughout the manuscript.
• Table 4: Please add the units for all reported parameters.
• I recommend strengthening the results section by including correlation analysis, which could help support the interpretation of results and the conclusions in relation to the study objectives.

Sinecerly,

Reviewer

Author Response

Dear Reviewer 1.

We have carefully reviewed our article and incorporated all changes, adjustments, corrections, and improvements, taking reviewers' comments and suggestions into account. Therefore, we are resubmitting an improved version of our manuscript entitled “Photoperiod modulates morphophysiological characteristics and yield of chia (Salvia hispanica L.) and arugula (Eruca sativa L.) microgreens under controlled conditions”, with reference number horticulturae-4200327.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Authors have revised the manuscript extensively to sharpen the introduction, justify methodological choices, strengthen quantitative presentation of results, clarify statistical reporting, and deepen the mechanism-oriented discussion. Suggest revising the format and language expression according to the publication requirements of the journal, and checking for errors in the images, tables, and text in the paper.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Dear Reviewer 1

We have carefully reviewed our article and incorporated all changes, adjustments, corrections, and improvements, taking reviewers' comments and suggestions into account. Therefore, we are resubmitting an improved version of our manuscript entitled “Photoperiod modulates morphophysiological characteristics and yield of chia (Salvia hispanica L.) and arugula (Eruca sativa L.) microgreens under controlled conditions”, with reference number horticulturae-4200327.

Below, we include a description of the changes made to the manuscript.

Best regards

 

Thank you in advance for your kind attention. We look forward to hearing your response.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear colleagues,
I have examined the revised version of the manuscript and note that the authors have generally addressed and incorporated the comments I raised during the previous review. However, I would like to express some reservations regarding certain reported values, particularly those expressed in mg per plant. The reported values (on the order of 0.30 mg, for example) appear to be very low. This raises concerns about the accuracy of the measurements, as well as the type and precision of the analytical balance used to obtain these results.
In contrast, the values expressed in mg/g seed seem more consistent and acceptable.
I therefore recommend that the authors verify the consistency of the units and the reported orders of magnitude (e.g., in mg per 10 seedlings). Otherwise, this parameter should be removed.

Sincerely,
Reviewer

Author Response

Hermosillo, Sonora, México, March 28, 2026

Dear Reviewer 2

We have carefully reviewed our article and incorporated all changes, adjustments, corrections, and improvements, taking reviewers' comments and suggestions into account. Therefore, we are resubmitting an improved version of our manuscript entitled “Photoperiod modulates morphophysiological characteristics and yield of chia (Salvia hispanica L.) and arugula (Eruca sativa L.) microgreens under controlled conditions”, with reference number horticulturae-4200327.

Below, we include a description of the changes made to the manuscript.

Author Response File: Author Response.pdf