Environmental Impacts of Plant Growth Regulators in Modern Agriculture: Advances, Risks, and Sustainable Perspectives
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors conducted an analysis of research results published over the last five years focusing on agronomic and environmental aspects of plant growth regulators usage. The study covers the impacts of plant growth regulators on target crops, consequences for soil microorganisms, aquatic ecosystems, and non-target organisms. Strategies for mitigating environmental risks are highlighted, including precision farming technologies and the development of biodegradable formulations. Visual schemes illustrating phenomena interrelationships and environmental impacts are clear and concise. Numerous important sources are cited. Future research directions are outlined, including long-term effects of low dosages and combined effects of mixed formulations.
The article can be published after minor revisions.
- Sections 6.1–6.3, focused on mitigation strategies: examples supporting the effectiveness of proposed measures should be added. For instance:
-Line 505: It would be beneficial to mention that a biodegradable auxin analogue based on indole-3-butyric acid extracted from algae degrades in soil by (90%, for example) in fewer days compared to a synthetic derivative.
-Line 493: Provide an example illustrating what percentage reduction in quantity and leaching into nearby water bodies can be achieved with spot application compared to traditional blanket spraying.
-Line 479: Demonstrate, using a specific example, by what percentage the content of the active ingredient in drainage water can be reduced without compromising the effectiveness of growth regulation.
2)Line 374: “reduced cocoon production” example value is desirable.
3)Line 18: “review synthesizes” is not so perfect. “In the current review we analyze (something)” would be better.
4)In Chapter 2, chemical structures of main representatives would be helpful.
Author Response
First reviewer
We thank the first Reviewer for the constructive and insightful comments. All the requested modifications have been implemented as suggested. All changes are highlighted in yellow, in accordance with the indications of the Reviewer and in agreement with the other reviewers. We sincerely appreciate the time dedicated to the evaluation of our manuscript and the valuable suggestions, which have contributed to improving the quality and scientific relevance of this review.
The authors conducted an analysis of research results published over the last five years focusing on agronomic and environmental aspects of plant growth regulators usage. The study covers the impacts of plant growth regulators on target crops, consequences for soil microorganisms, aquatic ecosystems, and non-target organisms. Strategies for mitigating environmental risks are highlighted, including precision farming technologies and the development of biodegradable formulations. Visual schemes illustrating phenomena interrelationships and environmental impacts are clear and concise. Numerous important sources are cited. Future research directions are outlined, including long-term effects of low dosages and combined effects of mixed formulations.
The article can be published after minor revisions.
- Sections 6.1–6.3, focused on mitigation strategies: examples supporting the effectiveness of proposed measures should be added. For instance:
-Line 505: It would be beneficial to mention that a biodegradable auxin analogue based on indole-3-butyric acid extracted from algae degrades in soil by (90%, for example) in fewer days compared to a synthetic derivative.
We thank the Reviewer for this valuable and constructive suggestion. We agree that including quantitative and comparative examples strengthens the discussion on mitigation strategies and improves the practical relevance of Sections 6.1–6.3. In response, we have revised Section 6.3 to incorporate a specific example of a bio-based, biodegradable auxin analogue derived from algal indole-3-butyric acid, highlighting its substantially faster degradation rate in soil compared to conventional synthetic derivatives. This addition provides concrete evidence supporting the environmental benefits of emerging bio-based plant growth regulators.
-Line 493: Provide an example illustrating what percentage reduction in quantity and leaching into nearby water bodies can be achieved with spot application compared to traditional blanket spraying.
We thank the Reviewer for this insightful comment. We agree that including a quantitative example improves the clarity and practical relevance of Section 6.1. Accordingly, we have revised the text to include a representative example from recent precision-application studies, illustrating the reduction in applied PGR quantities and associated decreases in leaching losses achieved through spot and site-specific application compared with conventional blanket spraying.
-Line 479: Demonstrate, using a specific example, by what percentage the content of the active ingredient in drainage water can be reduced without compromising the effectiveness of growth regulation.
We thank the Reviewer for this pertinent comment. We agree that providing a concrete quantitative example strengthens the discussion on the environmental benefits of optimized application strategies. Accordingly, we have revised Section 6.1 to include a specific example illustrating how adjusted application timing and dose optimization can substantially reduce the concentration of active ingredients in drainage water without compromising growth-regulating efficacy.
2)Line 374: “reduced cocoon production” example value is desirable.
We thank the Reviewer for this helpful suggestion. We agree that providing a quantitative example improves the clarity and scientific rigor of the discussion on sublethal effects of plant growth regulators on soil fauna. In response, we have revised the text in Section 4.3 to include a representative example quantifying the reduction in cocoon production observed under chronic exposure conditions.
3)Line 18: “review synthesizes” is not so perfect. “In the current review we analyze (something)” would be better.
We thank the Reviewer for this helpful linguistic suggestion. We agree that rephrasing the sentence improves clarity and readability of the Abstract. Accordingly, we have revised the wording to explicitly state the analytical scope of the review, while conserving the original meaning and reference base.
4)In Chapter 2, chemical structures of main representatives would be helpful.
We thank the Reviewer for this valuable suggestion. We agree that including the chemical structures of representative plant growth regulators would improve the clarity and didactic value of Chapter 2, particularly for readers from interdisciplinary backgrounds. In response, we have revised Chapter 2 to explicitly introduce and reference a new schematic figure illustrating the chemical structures of key natural and synthetic PGR representatives, without altering the original reference framework.
Reviewer 2 Report
Comments and Suggestions for AuthorsManuscript number: agrochemicals-4126715
Manuscript title: Environmental Impacts of Plant Growth Regulators in Modern Agriculture: Advances, Risks, and Sustainable Perspectives
Authors: Domenico Prisa, Aristidis Matsoukis, Aftab Jamal and Damiano Spagnuolo
The topic treated in the present manuscript is of potential interest for the Journal readership. The literature coverage is ample and up to date. The different aspects concerning the use and the potential environmental risks PGRs in modern agriculture are presented in a well structured and logical manner. Most importantly, a sincere effort is perceivable on the part of the Authors to go beyond a mere literature compilation and to produce a considered evaluation of the state of art, to guide the attention of the reader towards knowledge gaps, which should be the very primary goal of every review article.
In my opinion, only minor points should be addressed here:
1) Please check typos, as the one appearing on line 41 (“controlcell”).
2) Please avoid beginning a sentence with an acronym (e.g. line 46)
3) Please explain why on line 74-75 “pesticide persistence” is alluded to….What does it have to do with PGRs?
All the above considering, I recommend minor revision of the present manuscript, properly and carefully addressing all the points raised above.
Author Response
Second reviewer
We thank the second Reviewer for the careful evaluation of the manuscript and for the constructive comments provided. All the requested modifications have been implemented as suggested. The changes made in response to this Reviewer, in agreement with the other reviewers, are highlighted in light blue. We sincerely appreciate the valuable suggestions and the time dedicated to reviewing our work, which have contributed to improving the clarity and overall quality of the manuscript.
The topic treated in the present manuscript is of potential interest for the Journal readership. The literature coverage is ample and up to date. The different aspects concerning the use and the potential environmental risks PGRs in modern agriculture are presented in a well structured and logical manner. Most importantly, a sincere effort is perceivable on the part of the Authors to go beyond a mere literature compilation and to produce a considered evaluation of the state of art, to guide the attention of the reader towards knowledge gaps, which should be the very primary goal of every review article.
In my opinion, only minor points should be addressed here:
1) Please check typos, as the one appearing on line 41 (“controlcell”).
We thank the Reviewer for pointing out this typographical error. We have carefully revised the manuscript to correct this and similar minor typographical issues to improve clarity and readability.
2) Please avoid beginning a sentence with an acronym (e.g. line 46)
We thank the Reviewer for this helpful stylistic comment. We agree that avoiding acronyms at the beginning of sentences improves readability and conforms to standard scientific writing conventions. Accordingly, we have revised the indicated sentence to begin with the full term rather than the acronym.
3) Please explain why on line 74-75 “pesticide persistence” is alluded to….What does it have to do with PGRs?
We thank the Reviewer for this important clarification request. We agree that the original wording could create ambiguity. Plant growth regulators are regulated and applied within the broader category of agrochemicals and are therefore often evaluated using concepts and frameworks originally developed for pesticides, including persistence and environmental fate. To avoid confusion and to clarify relevance, we have revised the text to explicitly explain that the reference to pesticide persistence is used by analogy, reflecting shared environmental behavior and assessment approaches between pesticides and PGRs.
All the above considering, I recommend minor revision of the present manuscript, properly and carefully addressing all the points raised above.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors!
This review focuses on the investigations of environmental behavior and ecological impacts of widely used natural and synthetic PGRs.
There are some comments for Authors.
- It is recommended that the section 2.1. ‘Natural Phytohormones’ be expanded, as it would allow researchers get more information about this topic. It is desirable to add the characteristics of the IBA hormone to the review. Indole-3-butyric acid (IBA) is a, crucial plant hormone in the auxin family that acts as a powerful rooting agent to promote root initiation, stem cutting development, and lateral root growth. It is widely used in agriculture and horticulture to stimulate, enhance root systems, and increase overall plant, fruit, and flower yields. (Ludwig-Müller, J. Indole-3-butyric acid in plant growth and development. Plant Growth Regulation 32, 219–230 (2000). https://doi.org/10.1023/A:1010746806891 )
- It is recommended that the section 2.2. ‘Synthetic Plant Growth Regulators’ be expanded. It is desirable to add the characteristics of the 6-BAP hormone to the review. 6-Benzylaminopurine (6-BAP) is a synthetic, first-generation cytokinin plant hormone (growth regulator) that stimulates cell division, lateral bud development, and shoot proliferation. Widely used in plant tissue culture (e.g., in MS or Gamborg’s media) at 1–10 mg/L, it is effective for micropropagation, increasing fruit set, and maintaining chlorophyll in post-harvest vegetables. (Werner T., Schmulling T. (2009) Cytokinin action in plant development. Curr Opin Plant Biol 12: 527-538; Chhon Y., Sorn V., Seab Ph., Ung S., Kheang L., Ly V. Effect of 6-Benzylaminopurine (6-BAP) on Shoot Proliferation in Micropropagated Cavendish Banana (Musa acuminata) Wiley, International Journal of Agronomy Vol. 2025, 8 pages https://doi.org/10.1155/ioa/4870939 ).
Considering these comments, the article can be recommended for publication in ‘Agrochemicals’ after revision.
Author Response
Third reviewer
We thank the third Reviewer for the thorough evaluation of the manuscript and for the valuable and constructive suggestions. All the requested modifications have been implemented as suggested, and the changes are highlighted in green. We greatly appreciate the time and effort dedicated to reviewing our work, as well as the insightful comments, which have significantly contributed to improving the completeness and scientific quality of the manuscript.
- It is recommended that the section 2.1. ‘Natural Phytohormones’ be expanded, as it would allow researchers get more information about this topic. It is desirable to add the characteristics of the IBA hormone to the review. Indole-3-butyric acid (IBA) is a, crucial plant hormone in the auxin family that acts as a powerful rooting agent to promote root initiation, stem cutting development, and lateral root growth. It is widely used in agriculture and horticulture to stimulate, enhance root systems, and increase overall plant, fruit, and flower yields. (Ludwig-Müller, J. Indole-3-butyric acid in plant growth and development. Plant Growth Regulation 32, 219–230 (2000). https://doi.org/10.1023/A:1010746806891 )
We thank the Reviewer for this valuable and well-justified suggestion. We agree that expanding Section 2.1 improves the completeness of the review and provides additional insight into biologically and agronomically important natural phytohormones. In response, we have expanded Section 2.1 to include a dedicated paragraph on indole-3-butyric acid (IBA), describing its physiological role, agricultural applications, and relevance within the auxin family. The text incorporates the reference suggested by the Reviewer and is fully integrated into the existing structure of the section.
- It is recommended that the section 2.2. ‘Synthetic Plant Growth Regulators’ be expanded. It is desirable to add the characteristics of the 6-BAP hormone to the review. 6-Benzylaminopurine (6-BAP) is a synthetic, first-generation cytokinin plant hormone (growth regulator) that stimulates cell division, lateral bud development, and shoot proliferation. Widely used in plant tissue culture (e.g., in MS or Gamborg’s media) at 1–10 mg/L, it is effective for micropropagation, increasing fruit set, and maintaining chlorophyll in post-harvest vegetables. (Werner T., Schmulling T. (2009) Cytokinin action in plant development. Curr Opin Plant Biol 12: 527-538; Chhon Y., Sorn V., Seab Ph., Ung S., Kheang L., Ly V. Effect of 6-Benzylaminopurine (6-BAP) on Shoot Proliferation in Micropropagated Cavendish Banana (Musa acuminata) Wiley, International Journal of Agronomy Vol. 2025, 8 pages https://doi.org/10.1155/ioa/4870939 ).
We thank the Reviewer for this valuable and well-founded suggestion. We agree that expanding Section 2.2 improves the completeness of the review and provides important additional context on widely used synthetic cytokinins. In response, we have expanded Section 2.2 to include a dedicated paragraph on 6-benzylaminopurine (6-BAP), describing its physiological mode of action, principal agricultural and horticultural applications, and relevance in tissue culture and post-harvest systems. The revised text explicitly incorporates the references suggested by the Reviewer and is fully integrated within the existing section.
Reviewer 4 Report
Comments and Suggestions for AuthorsThis is an interesting paper about environmental impacts of plant growth regulators in modern agriculture. This review paper is extensive and well-written, and includes a large amount of published knowledge on the topic with rational analysis of different references. Further suggestions to improve the manuscript:
Line 48-50 - I suggest to indicate here that many natural phytohormones are synthesized by microorganisms, e.g. soil bacteria
Line 130-133 - suggest to add here that for preparation of formulation based on natural phytohormones especially IAA produced by and extracted from soil bacteria (e.g. Streptomyces) are of particular interest for the industry
Line 158-160 - suggest to mention here a couple examples of such synthetic products coming from some major companies on the market (e.g. from Bayer, BASF, Corteva or Sumitomo)
Line 340-530 - Figures - please clarify whether the pictures were generated with the use of generative AI tools
Line 627-628 - I suggest to mention that production of phytohormones at industrial scale often requires extensive fermentation processes
Author Response
We thank the fourth Reviewer for the careful evaluation of the manuscript and for the constructive and insightful comments. All the requested modifications have been implemented as suggested, and the corresponding changes are highlighted in brown. We sincerely appreciate the time and effort devoted to reviewing our work, as well as the valuable suggestions, which have contributed to improving the clarity, completeness, and overall quality of the manuscript.
This is an interesting paper about environmental impacts of plant growth regulators in modern agriculture. This review paper is extensive and well-written, and includes a large amount of published knowledge on the topic with rational analysis of different references. Further suggestions to improve the manuscript:
Line 48-50 - I suggest to indicate here that many natural phytohormones are synthesized by microorganisms, e.g. soil bacteria
We thank the Reviewer for this valuable suggestion. We agree that acknowledging the microbial synthesis of phytohormones provides important biological context and strengthens the discussion of plant–soil–microbe interactions. Accordingly, we have revised the text at Lines 48–50 to explicitly note that several natural phytohormones are also produced by soil microorganisms, while preserving the original references cited in this section.
Line 130-133 - suggest to add here that for preparation of formulation based on natural phytohormones especially IAA produced by and extracted from soil bacteria (e.g. Streptomyces) are of particular interest for the industry
We thank the Reviewer for this valuable and timely suggestion. We agree that highlighting the industrial relevance of microbially produced natural phytohormones strengthens the link between fundamental plant hormone biology and applied, sustainable formulation development. In response, we have revised the text at Lines 130–133 to explicitly note the growing interest in IAA produced by soil bacteria, such as Streptomyces, for the preparation of bio-based plant growth regulator formulations, while preserving all original references cited in this section.
Line 158-160 - suggest to mention here a couple examples of such synthetic products coming from some major companies on the market (e.g. from Bayer, BASF, Corteva or Sumitomo)
We thank the Reviewer for this constructive suggestion. We agree that providing concrete examples of commercially available synthetic plant growth regulators enhances the practical relevance of this section and helps readers better contextualize their widespread use in agriculture. Accordingly, we have revised the text at Lines 158–160 to include representative examples of synthetic PGR products developed and marketed by major agrochemical companies, while fully preserving the original reference framework.
Line 340-530 - Figures - please clarify whether the pictures were generated with the use of generative AI tools
We thank the Reviewer for raising this important point. In the interest of transparency and compliance with current editorial policies, we clarify that the figures included in this manuscript are conceptual and illustrative schematics prepared by the authors for explanatory purposes. Where digital tools were used to assist in the visualization process, these tools served only as graphical aids, and all figures were subsequently reviewed, verified, and finalized by the authors to ensure scientific accuracy and consistency with the text. No figures are intended to represent experimental data or observations. To avoid ambiguity, we have added a clarifying statement to the manuscript specifying the nature and purpose of the figures.
Line 627-628 - I suggest to mention that production of phytohormones at industrial scale often requires extensive fermentation processes
We thank the Reviewer for this insightful suggestion. We agree that acknowledging the industrial production requirements of phytohormones provides important practical context, particularly in discussions of scalability and sustainability. In response, we have revised the text at Lines 627–628 to explicitly note that large-scale production of phytohormones commonly relies on fermentation-based processes, while preserving all original references cited in this section.
