Application of Spirulina platensis and Chlorella vulgaris for Improved Growth and Bioactive Compound Accumulation in Achillea fragrantissima In Vitro
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsAvoid using terminology such as “high concentrations” (line 17 of the abstract)… Include the actual values. Review this issue in other parts of the abstract as well.
Lines 55–57: better explain the issue of sterile cultivation, particularly regarding the importance of conducting it under these conditions and considering the production and market potential. Why is studying these conditions important?
Line 110: replace the session title to indicate what is intended to be analyzed by GC–MS. The focus is on the compounds, not on the analytical method.
Check the caption of Figure 2 and review the others: the sample 0.0+0.5 is duplicated in the caption.
Make it clearer in the text, whenever this citation appears, what is meant by moderate, low, or high application doses, including in the abstract and in the conclusions.
Author Response
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsReview for the paper “Application of Spirulina platensis and Chlorella vulgaris for Improved Growth and Bioactive Compound Accumulation in Achillea fragrantissima In Vitro” by Soulaima Azizi and co-authors submitted to “Phycology”.
The authors of this research paper conducted an analysis of the effects of microalgal biostimulants on the in vitro propagation of a medicinal plant, Achillea fragrantissima. They investigated the individual and combined applications of aqueous extracts from Spirulina platensis and Chlorella vulgaris on plant growth, photosynthetic performance, and secondary metabolite production. They found that the algal extracts significantly enhanced shoot proliferation and leaf development in a dose-dependent manner. The physiological responses were distinct, with each algal species promoting different aspects of growth and metabolism, attributed to their unique biochemical profiles. A particularly important discovery was the synergistic effect observed when the two extracts were combined. This combination treatment not only improved biomass accumulation but also profoundly altered the plant's metabolic profile, leading to a marked increase in the synthesis of several valuable bioactive compounds, including fatty acid derivatives and phytol, compared to control plants and those treated with a single alga. The results of this study may have important implications for developing sustainable plant biotechnology platforms.
Recommendations.
Introduction
L 58-59. I think the authors should add a few concrete examples of these compounds and plant species from the literature to back up the statement that algal biofertilizers can boost the production of specific bioactive compounds. This would make the claim much more convincing and easier to follow.
L 63. I would suggest that the authors spell out more clearly what exact knowledge gap this study is addressing. They could also briefly refer to any previous work on how these microalgae affect Achillea fragrantissima to better position their contribution.
Materials and Methods
L 73. It would help if the authors briefly summarized the key details of the extraction method, including the solvent-to-biomass ratio, extraction time, temperature, and the type of water used (e.g., distilled or deionized).
L 75-77. I would suggest that the authors briefly explain the basic analytical principles and list the instruments used for these measurements, so readers can better understand and reproduce the analyses.
L 81-82. The authors should report the voucher specimen number and the herbarium where it is deposited. They should also describe the “standard protocols” used to ensure seed viability, at least in brief. It is unclear what specific procedures were followed.
L 104-105. I think the authors should add the exact drying conditions (temperature and duration) and give a more detailed description of the methanol extraction protocol (solvent volume, extraction time, and method).
L 109. It is unclear which extraction solvent was used here. I would suggest that the authors clearly state the solvent and any relevant conditions.
L 118. The authors should indicate whether they checked for normality and homogeneity of variance before running parametric tests (ANOVA), and specify which tests or procedures they used for these assumptions. It is unclear how they validated the use of ANOVA.
Results
L 136. I think the authors should provide actual quantitative data at this point to support the comparative statement they are making, so that the reader can evaluate the magnitude of the differences.
Table 3. It is unclear how the different letters are being used in the table, since their meaning is not explained. I would suggest that the authors define the lettering system (e.g., for significance groups) in a footnote, and clarify why the value 16.67 in the “Callus” column is labeled with either “ab” or “b.” In my opinion, the mean values should also be shown with their standard errors.
Discussion
L 264-267. I think the authors should provide measured or literature-based levels of phycocyanin and vitamin E in S. platensis to support this argument more solidly.
L 261-263. The authors should discuss possible explanations for the inhibitory effect observed at lower concentrations, such as sub-threshold elicitation or the induction of mild stress responses.
L 281. I would suggest that the authors specify which particular precursors from S. platensis are relevant to the biosynthetic pathways of the metabolites that increased in A. fragrantissima. It is unclear which metabolites and pathways they have in mind.
Finally, I think the authors should add a short section discussing the practical implications of their findings, for example how these results might be applied in agriculture, phytopharmaceutical production, or biofertilizer development.
Author Response
Author Response File: Author Response.pdf
