Effects of Fertigation Programs and Substrates on Growth, Fruit Quality, and Yield of Bell Pepper (Capsicum annuum) in Greenhouse Conditions

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a well-structured and timely investigation into a topic of significant agricultural importance, particularly for the growing greenhouse industry in the Dominican Republic. The study is sound in its factorial design, employs appropriate statistical analyses (ANOVA, PCA, MANOVA), and addresses a clear knowledge gap regarding the interaction between fertigation and substrates. The findings are valuable and have practical implications. However, the manuscript requires substantial revisions to enhance clarity, depth of interpretation, and adherence to scientific reporting standards. 
Major Concerns and Required Modifications:
1.The description of the experimental layout in Section 2.1.2 and Table 2 is confusing. The number of "repetitions" is listed as 4, 4, 3, 3, 2, 2, 1, 1, which is highly unorthodox and suggests an unbalanced design. A standard split-plot design should have an equal number of replications for each main plot.
Question:​ Please clarify the replication structure. Was this a completely randomized design with four replications, and is Table 2 potentially mislabeled? A clear schematic or a more standard table presentation is needed.
2.The use of MANOVA is noted, but the rationale for its application over multiple ANOVAs is not justified. Furthermore, the results of the MANOVA in Table 4 are presented as univariate means, which is inconsistent. The caption mentions Hotelling's test, but the table uses letters for separation as in ANOVA.
Question:​ Please justify the use of MANOVA. If MANOVA was significant, were the subsequent ANOVAs considered protected tests? The presentation of Table 4 must be corrected to clearly show MANOVA results (e.g., Wilks' Lambda) followed by univariate ANOVAs.
3.The PCA biplots (Figures 2 and 3) are valuable. However, their interpretation in the text is qualitative. A more quantitative description is needed, such as discussing the loadings of the variables on the principal components to support claims about which variables contributed most to the separation.
Question:​ Can you augment the results section for the PCA by briefly mentioning the variable loadings for PC1 and PC2 to strengthen the interpretation?
4. The discussion correctly links plant performance to substrate physical properties (Table 3). However, it remains superficial. The connection between, for instance, the fast drainage of CF and its lower yield needs a deeper physiological explanation (e.g., impact on nutrient uptake frequency, potential for drought stress between irrigation events).
Question:​ Can you expand the discussion in Section 4.1 to elaborate on the mechanistic reasons why the physical properties of the substrates led to the observed growth differences?
5.The authors note that total yield data were log-transformed for analysis, which is a valid procedure. However, Table 7 presents the back-transformed means alongside standard errors, which is statistically incorrect as the standard errors are not symmetrical on the original scale.
Question:​ It is standard practice to present the means and standard errors (or confidence intervals) from the analysis on the transformed scale, or to clearly state that the values in the table are back-transformed from the log-scale means. Please clarify the presentation in Table 7.
6.The discussion includes comparisons with other studies but often stops at stating whether results are similar or different. A more critical analysis is needed. For example, when citing a study that found optimal results with medium nitrogen doses, the authors should hypothesize why their study showed superiority of high doses (e.g., differences in substrate cation exchange capacity, environmental conditions, or cultivar).
Question:​ Can you deepen the discussion by not just comparing results, but also providing plausible explanations for the discrepancies or agreements with the existing literature?
7.The authors correctly note that their total yield is lower than some references because the experiment was terminated early while the crop was still productive. This is a significant limitation that affects the interpretation of the yield data.
Question:​ Please state the reason for terminating the experiment at 141 DAT in the Methods section. Was this due to time constraints, a predefined experimental protocol, or external factors? This justification is crucial for readers.
8.The conclusion recommends FP3-BRH but does not discuss potential trade-offs, such as the cost of the high nutrient program versus the marginal yield increase over FP2-BRH. A brief consideration of economic viability or nutrient use efficiency would greatly strengthen the impact of the conclusion.
Question:​ Can you add a sentence or two in the conclusion discussing the practical and economic implications of adopting the recommended FP3-BRH strategy compared to other promising combinations like FP2-BRH?
9.The references contain formatting inconsistencies (e.g., journal names in italics, volume numbering). Some URLs lack access dates. All references must be formatted consistently according to the journal's guidelines.
Question:​ Please meticulously check and format every reference to ensure complete consistency.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is scientifically sound and makes a valuable contribution to greenhouse horticulture research. Addressing the issues outlined points in here and in the attached pdf will significantly enhance its impact, clarity, and credibility:

• the title is too long. max 15 words
• make sure all scientific names are italic
• try to add comma instead of dash
• in the introduction: try to separate paragraphs instead of  long ones
• in the introduction: a paragraph reviewing the effect of nutrient use efficiency of bell paper or other crops need to be discussed.
• Reformulate the hypothesis into one concise statement, and avoid stating the conclusion
• what is the cultivar name of bell pepper
• Table 1: what is FP? need to provide the full name in the table foot note
• M&M: (CF: 100% coconut fiber; BRH: 100% carbonized rice husk; 1:1 Mix: mixture of 50% CF + 50% BRH. ) Table 1
• Table 2: better illustration as a figure
• in the M&M remove the repeated sentences.
• statistical analysis, LSD at at p<(0.05 or 0.10)?
• Clarify whether PCA and MANOVA were conducted on plot means or individual plant observations.
• table 6: Standardize all abbreviations throughout the manuscript
• results: yield per sqr meter? or per m
• Yield is reported in kg m⁻², but comparisons with literature values (e.g., 10 kg m⁻²) are made without clarifying cycle length.
• more comments in the pdf

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The study addresses a relevant and well-defined agronomic problem, particularly important for protected horticulture in tropical and subtropical regions. The experimental design is appropriate, the dataset is extensive, and the statistical analyses are generally sound. The manuscript is publishable in its current form, but several aspects could be clarified, tightened, or strengthened to improve scientific rigor, generalisability, and interpretability.

-The hypotheses are stated at the end of the Introduction, but they are broad and descriptive. Please improve the text

-The three fertigation programs (FP1–FP3) are well described numerically, but the physiological or agronomic rationale behind the chosen nutrient ranges is insufficiently justified. Please improve the text

_The study focuses strongly on physical substrate properties (drainage, retention, bulk density). However, chemical properties of substrates (CEC, inherent nutrient contribution, buffering capacity) are not addressed.

_The manuscript uses “carbonized rice husk” and “rice husk biochar” interchangeably. These materials can differ significantly depending on pyrolysis temperature and process. Please, clarify.

-PCA and MANOVA are used appropriately and add value. However, PCA interpretation is sometimes over-descriptive and could be more biologically integrated. Please, improve.

_Yield differences are attributed mainly to substrate water–nutrient dynamics. However, assimilate partitioning, sink strength, and fruit load regulation are not discussed.

_The experiment was terminated while plants were still productive. This is acknowledged, but its implications are under-emphasised. Please, clarify

_The Discussion is thorough but occasionally repetitive, especially when restating Results. Please, verify /reformulate.

-Conclusions are clear, evidence-based, and well aligned with results. Recommendations are practical and relevant could be added.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has made revisions according to the opinions of experts. The paper has excellent research content and value, and it is recommended to be accepted for publication.