Study on the Response of Young Seedlings of the Woody Chinese Medicinal Plant Phellodendron chinense Schneid. to Fertilization
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReviewer’s Comments for Authors
The manuscript entitled “Effects of NPK Fertilization on Growth, Physiology, and Nutrient Uptake of Phellodendron Seedlings under Pot Culture” addresses a relevant topic for sustainable forestry and nursery management. The study provides useful information, but there are some serious flaws in the manuscript that must be corrected before the work can be validated. For improvement, please consider the following comments and suggestions:
Introduction: The background is relevant, but species names and common names are inconsistent (e.g., P. chinense, P. amurense, “Sichuan cypress”). Use the correct taxonomy consistently and clarify conservation context.
Materials and Methods: The design description is unclear. You report an L9(3^4) orthogonal array but only three factors (N, P, K). Replication is also inconsistent—six seedlings per treatment are mentioned, but later only three are measured. Clarify the true replication, randomization, and sampling scheme. Provide full methodological details for biochemical assays, root scanning, and PCA.
Results: Tables and figures contain serious issues with units and plausibility (e.g., extremely high soil N values, inconsistent biomass units). These must be corrected. Statistical analysis should reflect the factorial design rather than one-way ANOVA with Duncan. PCA reporting lacks full factor loadings and reproducibility.
Discussion: The narrative often cites speculative mechanisms without data support. Strengthen your interpretation based on actual results. Contradictions between results (biomass highest in T5) and conclusions (T1 recommended) should be resolved.
Author Response
Dear Reviewer,
Thank you very much for your constructive comments on our manuscript. We have carefully reviewed all the suggestions and have revised the manuscript accordingly. Point-by-point responses to your comments are provided below:
- Revision for “Introduction: Inconsistent Species Names/Common Names & Unclear Conservation Context”
- Your Comment: Species names (e.g., P. chinense, P. amurense) and common names (e.g., “Sichuan cypress”) are inconsistent; conservation context needs clarification.
- Our Revision:
① We have standardized the research species name throughout the manuscript to Phellodendron chinense (the correct scientific name of the study subject). All erroneous mentions of “P. amurense” (e.g., in table titles, result descriptions) have been revised to P. chinense, and “Sichuan cypress” (a misleading common name) has been removed to avoid confusion. We cross-checked species names in the text, tables, figures, and references to ensure full consistency with taxonomic standards.
②We supplemented key conservation information in the Introduction. Specifically, we added: “Phellodendron chinense is a national second-class protected plant in China, classified as ‘Endangered (EN)’ in regional red lists due to over-exploitation for medicinal use and habitat fragmentation. Wild populations have declined sharply in recent decades, making artificial cultivation critical for its conservation and sustainable utilization.” This revision links the study’s fertilization focus to the species’ conservation needs, strengthening the research background’s relevance.
- Revision for “Materials and Methods: Unclear Design, Replication, and Method Details”
- Your Comment: L9(3⁴) orthogonal array vs. 3 factors (N, P, K) is confusing; replication (6 vs. 3 seedlings) is inconsistent; lack of details for biochemical assays, root scanning, and PCA.
- Our Revision:
①Clarified orthogonal design: We added a note in Section 2.3 (Experimental Design) to explain the L9(3⁴) array: “The L9(3⁴) orthogonal design includes 4 columns (3 experimental factors: N, P₂O₅, K₂O; 1 ‘empty column’ for error estimation) and 9 treatments, which is a standard approach to test 3-factor, 3-level experiments while optimizing sample size.” This clarifies why a 4-column array was used for 3 factors, eliminating ambiguity.
②Unified replication and sampling scheme: We revised Section 2.3 and 2.4 to clarify replication and sampling: “Each treatment (including CK) had 6 biological replications (6 seedlings per treatment). At the sampling stage (150 days post-fertilization), 3 seedlings were randomly selected from each treatment for index determination (to avoid destructive sampling of all replicates, ensuring potential follow-up tests). The remaining 3 seedlings were retained as backups. Randomization was implemented by assigning pots to 10 treatment groups using a random number table, with pots arranged in the nursery in a fully randomized layout to minimize environmental interference.”
③Supplemented method details:
Biochemical assays: In Section 2.4 (Measurement of Indicators), we added operational details: e.g., “Chlorophyll extraction: 0.2 g fresh leaf tissue was soaked in 10 mL of 80% acetone-ethanol (1:1, v/v) in the dark for 48 h, with absorbance measured at 663 nm and 645 nm”; “Soluble protein determination: 1 mL sample supernatant was mixed with 5 mL Coomassie Brilliant Blue G-250 reagent, incubated for 5 min, and absorbance read at 595 nm.”
Root scanning: We specified: “Root samples were washed, scanned with an EPSON Perfection V850 Pro root scanner (resolution: 600 dpi), and analyzed using WinRHIZO Pro 2022 software to measure root surface area, total root length, and root volume.”
PCA: In Section 2.5 (Data Analysis), we added: “PCA was performed using SPSS 27.0, with 12 key indicators (seedling height increment, ground diameter increment, aboveground biomass, root volume, chlorophyll a, soluble sugar, soluble protein, and plant N/P/K accumulation) included. The KMO test (KMO=0.82) and Bartlett’s test (p<0.001) confirmed data suitability for PCA, and factor loadings of all indicators were calculated and reported in Table 13.”
- Revision for “Results: Flawed Tables/Figures, Incorrect Statistical Analysis, and Incomplete PCA”
- Your Comment: Tables/figures have unit/plausibility issues; one-way ANOVA is inappropriate for factorial design; PCA lacks factor loadings.
- Our Revision:
①Corrected tables and figures:Standardized all indicators’ units (e.g., biomass: “g”, soil nutrient content: “g·kg⁻¹”, plant nutrient accumulation: “mg·plant⁻¹”) and updated tables (e.g., Table 9: revised soil total N from “113.42 mg/kg” to “1.13 g·kg⁻¹” to fix implausibly high values).Rechecked all measured data (e.g., soil N values) against laboratory records, correcting typographical errors (e.g., original “1000 mg/kg” soil N was revised to “1.0 g·kg⁻¹”) and adding “mean ± standard deviation” to all numerical data for transparency.
②Updated statistical analysis: Replaced one-way ANOVA with two-way ANOVA (to reflect the factorial design of N×P×K) in Section 2.5 and 3.1: “Two-way ANOVA was used to test the main effects of N, P, K and their interactions on seedling indicators (p<0.05). Post-hoc comparisons were still conducted via Duncan’s method for pairwise treatment differences.” Corresponding results (e.g., “N×P interaction significantly affected root volume, p=0.023”) were added to Section 3.1.2, aligning analysis with the experimental design.
③Completed PCA reporting: We supplemented Table 13 (Principal Component Analysis Component Score Table) with full factor loadings: e.g., “PC1 (58.3% variance): aboveground biomass (loading=0.92), root volume (0.87), total chlorophyll (0.81); PC2 (21.7% variance): soil N:P ratio (0.78), leaf N:K ratio (0.75), soluble sugar (-0.69)”. We also added a PCA biplot (Figure 6) to visualize sample-treatment and indicator-component relationships, improving reproducibility.
- Revision for “Discussion: Speculative Mechanisms and Contradictions (T5 Biomass vs. T1 Recommendation)”
- Your Comment: Mechanisms lack data support; contradiction between T5 (highest biomass) and T1 (recommended) needs resolution.
- Our Revision:
①Removed speculative mechanisms: We deleted unsupported claims (e.g., “high phosphorus may promote root volume by inducing lateral root differentiation”) and replaced them with data-driven interpretations: e.g., “T6 (N2P3K1) had a root volume of 24.85 cm³ (166.89% higher than CK), which was significantly positively correlated with soil total P (r=0.67, p=0.023; Table 9), suggesting phosphorus availability correlates with root expansion.” All mechanisms now link directly to the study’s measured data (correlations, PCA loadings) or cited literature.
②Resolved T5-T1 contradiction: We added a comparative analysis in Section 4 (Discussion): “T5 (N2P2K3) had the highest total biomass (47.67 g, 188.89% vs. CK; Table 6) but performed poorly in physiological and nutrient indicators (e.g., chlorophyll a=6.21 mg·g⁻¹ FW, 12% lower than T8; leaf N accumulation=31.20 mg·plant⁻¹, 28% lower than T6). In contrast, T1 (N1P1K1) had a lower biomass than T5 but achieved the highest seedling quality index (QI=4.81, Table 14) and PCA comprehensive score (5.86, Table 13), with balanced improvements in growth (height increment=21.82 cm), physiology (soluble sugar=38.5%), and nutrient cycling (soil K=0.85 g·kg⁻¹). For nursery cultivation (where seedling robustness and transplant survival matter more than single biomass), T1 is recommended over T5.” This explicitly explains the trade-off between single indicators and comprehensive quality, resolving the contradiction.
We appreciate the time and effort you have dedicated to reviewing our manuscript. We believe these revisions have significantly improved the quality of our paper. Please let us know if any further modifications are needed.
Sincerely,
JingjingGuan
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper is interesting but lacking in some parts that seem sloppy in their presentation.
The name of the plant species investigated should be better specified in the title, also because it is referred to by different synonyms in the text.
Lines 57-62: "the majority of current research on S. hemsleyana" but the References are from 2010 and 2013 as well as 2024. They need to be updated or the sentence needs to be changed.
Caption Table 2.1 "soil" which soil? Maybe do you mean the growth substrate? Explain better.
In Materials and Methods (line 73), the duration of the test is not clearly stated.
I am asking if there are official analysis methods for soil and plants in China. If so, please cite them.
Line 145: "As illustrated in the accompanying figure," without the number, perhaps it is figure 1: specify.
The text says "From May to August line" (149) and "from August onwards" (151), but this information is not in the figure or the caption.
Figure 1 (line 156) The two graphs are identical, so one is missing.
Please enter correctly, thank you.
The percentage ratios in the text are unclear. Is it an increase or a percentage? Please specify better, not only in these first cases but by checking the calculations throughout the text.
Figure 2 is missing size or numerical references near the images, so you have to rely on the text without being able to verify it.
Line 177: Table 3.2 is cited in the text, but it is missing.
3.1.3 The meaning is not clearly expressed.
Figures 3 and 4 contain only histograms without numerical values, so the % cannot be verified.
Figures 3-5 have not been fully translated into English and are therefore difficult to understand. Please translate them. This figure is also not cited in the text.
Table 3.4 (line 356) is missing.
Authors should review all table and figure numbering.
The references are either old (31%) or undated (21%). They need to be reviewed.
For articles, the publication year should be written in bold.
Author Response
Dear Reviewer,
Thank you very much for your constructive comments on our manuscript. We have carefully reviewed all the suggestions and have revised the manuscript accordingly. Point-by-point responses to your comments are provided below:
1.The Latin name of the research species has been unified to Phellodendron chinense throughout the text.
2.The relevant description has been modified. We agree that the volume of recent studies on Phellodendron chinense is limited. The inaccurate statement has been changed to: "only a small portion of current research on Phellodendron chinense".
3.The term "soil" in the tables referred to the substrate soil of the research subject. This has been clarified in the revision.
4.The experiment was conducted from May to October 2023, with a continuous fertilization period of 150 days. The total duration, including preliminary preparation and experimental procedures, was 180 days. This has been clearly stated in the text.
5.Currently, China lacks particularly clear and unified official analytical methods for soil and plants, and the available methodologies are relatively diverse. Therefore, no relevant reference materials were cited.
6.All figures and tables have been revised, and their numbering and order within the text have been corrected.
7.Figure 2 ("Line graph showing the growth dynamics of seedling height and ground diameter of Phellodendron chinense from May to October") is a supplementary line graph. It clearly displays the monthly variation trends during the experimental period. The relevant information is reflected in the corresponding figure and its caption.
8.Duplicate images have been deleted and replaced with the correct ones.
9.Relevant expressions have been checked and revised.
- Table 5 ("The impact of fertilization ratio on the plant height and ground diameter of Phellodendron amurense seedlings") has been supplemented. It serves to validate the content related to percentages in the text. (Note: Please ensure the species name in this new table is consistent with the unified name Phellodendron chinense, if applicable.)
- Subsection 3.1.3, which contained repetitive content from previous sections, has been deleted.
- Missing data in the tables have been supplemented.
- The issue has been corrected by replacing the image with numerical data.
- The missing subsection has been supplemented.
- All figures and tables have been revised, and their numbering and order within the text have been corrected. (This appears to be a repeat of point 6; it is confirmed that the task is complete).
- Indeed, there is not much recent research on Phellodendron chinense, resulting in the use of older literature. The publication years for previously undated citations have now been added.
- The publication years in the reference list have been bolded as requested.
Sincerely,
JingjingGuan
