Enhancing Rhizobium–Legume Symbiosis and Reducing Nitrogen Fertilizer Use Are Potential Options for Mitigating Climate Change
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
These authors reviewed the effects of nitrogen fertilizers on the symbiotic relationship between rhizobium and legume plants. The symbiotic relationship between rhizobium and legume plants plays an important role in sustainable agriculture. While, excessive nitrogen fertilization can negatively affect their symbiotic relationship. Thus, it is necessary to address the effects of excessive nitrogen fertilizer on this symbiotic relationship in order to enhance nitrogen fixation and crop growth. Overall, it is well-organized and well-written paper. Nevertheless, I suggest these authors to construct a figure to convey their ideas that how nitrogen fertilizers affect the symbiotic association between rhizobium and legumes, and the potential strategies to improve nitrogen fixation and plant growth. Moreover, these authors need to pay an attention to the use of subscript in chemical symbols.
Comments on the Quality of English Language
Minor editing of English language required.
Author Response
Dear Prof Dr ;
Thank yo very much for your effort and time involved in this review process. Attached is my response to your suggestions and comments
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
The full text has sufficient evidence and the research content is of great practical significance. However, some chapters in the paper have repetitive content that needs to be merged and organized, and the structural framework needs to be adjusted. The specific suggestions are as follows:
1. The title of the paper does not properly reflect the main content of the paper, and it is recommended to adjust it;
2. The introduction in the preface is too long and needs to be summarized and condensed. The second paragraph in section 1.2 is repetitive with the content in section 1.3, and it is recommended to merge it;
3. It is recommended to list a separate chapter on the Effects of N fertilizer , and a separate chapter on the Biological Nitrogen Fixation Systems.
4. Missing section 3.3
5. The content under the second level title of Part 4 is too simple, and one sentence cannot support one sub-section. It is recommended to merge or adopt other forms of expression
6. The literature cited in this article is very rich, but limited in length, it is recommended to mainly retain literature from the past 5 or 10 years and delete unimportant literature.
Author Response
Dear Prof Dr.
Thank you very much for your effort and time involved in this review process. The attached file is my response to your suggestion and comments.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
I think the “abstract” doesn’t match the title. It discusses too much about the symbiotic relationship n Rhizobium bacteria and leguminous plants and the effects of nitrogen fertilizer on it. I don’t find the strategies and how to achieve climate change mitigation. The author should modify it.
In Line 79, GHG should be replaced by the “greenhouse gas”.
In Line87, N2O should be modified to “N2O”.
In Line116, CO2 should be modified to “CO2”.
In Line 189, “)” should be deleted.
Lines 191, please check it carefully.
In 4.4 Improving soil fertility, the author should modify it and further explain how soil fertility mitigate the negative effects.
In Line 970, please the author check the “Reference” format.
The format of “Reference” is inconsistent. Please check them.
Author Response
(Reviewer 3)
Thank you for your email dated 4-10-2023 and for your valuable comments and suggestions on our manuscript number agriculture-2638150, titled " Enhancing Rhizobium-legume symbiosis and reducing nitrogen fertilizer use are potential options for mitigating climate change."
1. I think the “abstract” doesn’t match the title. It discusses too much about the symbiotic relationship n Rhizobium bacteria and leguminous plants and the effects of nitrogen fertilizer on it. I don’t find the strategies and how to achieve climate change mitigation. The author should modify it.
Yes, the title has been reformed and the revised version has been improved.
2. In Line 79, GHG should be replaced by the “greenhouse gas”.
Yes, GHG has been replaced by the “greenhouse gas”.
3. In Line87, N2O should be modified to “N2O”
Yes, N2O has been replaced by “N2O”
4. In Line116, CO2 should be modified to “CO2”
Yes, CO2 has been replaced by “CO2”
5. In Line 189, “)” should be deleted.
Yes, deleted.
6. Lines 191, please check it carefully.
Yes, corrected.
7. In 4.4 Improving soil fertility, the author should modify it and further explain how soil fertility mitigate the negative effects.
Yes, this section has been improved as follows:
- Mitigation Strategies
To mitigate climate change, it is crucial to find sustainable solutions for reducing nitrogen fertilizer use. One promising approach is through the utilization of Rhizobium-legume symbiosis. By harnessing this natural symbiosis, farmers can reduce their reliance on synthetic nitrogen fertilizers. This is significant because the production and application of nitrogen fertilizers contribute to greenhouse gas emissions, particularly nitrous oxide, which is a potent greenhouse gas (Figure 5). To encourage the adoption of this approach, education and outreach programs should be implemented to raise awareness among farmers about the benefits of Rhizobium-legume symbiosis. Additionally, research and development efforts should focus on optimizing the efficiency of nitrogen fixation in legume crops and identifying suitable Rhizobium strains for different soil conditions. Reducing nitrogen fertilizer use through Rhizobium-legume symbiosis is a promising strategy for climate change mitigation (Compant et al., 2010; Olivares et al., 2013). To enhance the symbiotic relationship between Rhizobium and legumes and reduce reliance on nitrogen fertilizers for climate change mitigation, several strategies can be implemented: - Selecting effective rhizobial strains: To enhance nodulation and nitrogen fixation efficiency, it is crucial to carefully select specific rhizobial strains. This can be accomplished by screening and choosing strains that have a higher compatibility with legume plants. This approach brings numerous advantages in addressing climate change, such as decreased fertilizer usage, improved soil health and carbon sequestration, enhanced plant resilience, and economic benefits for farmers (Olivares et al., 2013; Mabrouk et al., 2018; Roy et al. 2020). - Crop rotation and intercropping: Rotate legume crops with non-leguminous crops to break pest and disease cycles and promote nitrogen cycling in the soil. Intercropping legumes with other crops can enhance nutrient cycling and reduce the need for nitrogen fertilizers. - Using cover crops: Planting cover crops, especially leguminous plants, during fallow periods can enhance soil health and increase the availability of nitrogen. (Jensen et al. 2013). These cover crops can fix atmospheric nitrogen, making it accessible to subsequent crops (Grover et al. 2023). - Improving soil fertility: Employ practices such as organic matter addition, composting, and proper nutrient management to enhance soil fertility (Dubey et al., 2019). Organic fertilizers, crop residue incorporation, and balanced nutrient application can reduce the need for nitrogen fertilization. Soil fertility is crucial for maximizing carbon sequestration, promoting nutrient cycling, improving water retention, supporting biodiversity, and reducing erosion (Oren et al. 2001; Kane and Solutions, 2015). Fertile soils contribute to resilient and sustainable agricultural systems that help mitigate the negative effects of climate change (Elbasiouny et al. 2022). - Proper soil management: Practice good soil management techniques to create a favorable environment for Rhizobium-legume symbiosis and microbial communities (Mukhtar et al., 2023). Maintain optimal soil pH, proper drainage, and avoid excessive use of nitrogen fertilizers, which can hinder nodulation and nitrogen fixation. Healthy soils are crucial for storing carbon and mitigating climate change. When managed sustainably, soils can sequester carbon and reduce greenhouse gas emissions. However, poor soil management and unsustainable agricultural practices can release carbon into the atmosphere, contributing to climate change (Figure 8). The conversion of grassland and forestland to cropland and grazing lands has led to significant soil carbon losses worldwide. By restoring degraded soils and adopting soil conservation practices, we can decrease greenhouse gas emissions, increase carbon sequestration, and build resilience to climate change (Scharlemann et al.,2014). Land use, land-use change, vegetation cover, and soil management strongly influence the processes and emissions of greenhouse gases in the soil. Managing soil organic carbon stocks in the upper soil layers can help reduce greenhouse gas concentrations in the atmosphere (Bayu , 2020). - Optimizing inoculation techniques: Ensure the proper inoculation of legume seeds with efficient rhizobial strains. This involves using appropriate inoculant formulations and ensuring proper seed coating or inoculant application to improve symbiosis establishment (Company et al. 2010). Factors such as bacterial strains, inoculant formulation, application methods, and environmental conditions all play a role in successful inoculation. By improving our understanding and application of these techniques, we can maximize the benefits of symbiotic nitrogen fixation and contribute to climate change mitigation efforts (Shah et al.,2021) - Improving farming practices: Adopt conservation agriculture practices, including reduced tillage, mulching, and water management techniques. These practices enhance soil structure, increase soil organic matter, and reduce nitrogen losses, maximizing the benefits of Rhizobium-legume symbiosis (Jena et al., 2022). By adopting and implementing these improved farming practices, agricultural systems can become more resilient, efficient, and sustainable. This, in turn, helps to reduce the negative impacts of climate change on food production, ecosystems, and the environment. It is crucial to adopt these approaches to preserve nature and its benefits to humanity, while also ensuring the availability of good food at reasonable prices and protecting the environment for our survival (Muhie , 2022). - Integrated nutrient management: Combine Rhizobium inoculation with judicious application of mineral fertilizers to optimize nitrogen availability. This integrated approach ensures adequate nutrient supply while minimizing the use of synthetic fertilizers (Choudhary et al.,2018; Gurjar et al., 2022; Tomar and Bhatnagar, 2022). - Rhizobial inoculant quality control: Verify the effectiveness of commercially available rhizobial inoculants through field trials or consultation with experts (Obando et al., 2019, Jansson, and Hofmockel, 2020; Wong et al., 2022). Use commercially available inoculants or isolate local strains proven to be effective in your specific region. Castellano-Hinojosa et al. (2022) research findings indicate that native rhizobia have a greater positive impact on plant growth, nitrogen fixation, and reduction of greenhouse emissions in sunnhemp crops within Florida citrus orchards, compared to commercial rhizobia inoculants (Woliy et al.,2019). Maintain proper storage conditions, follow application instructions, and use fresh inoculants to maximize efficacy. - Genetic improvement: Employ breeding programs to develop legume cultivars with improved compatibility with specific Rhizobium strains. This can be achieved through marker-assisted selection or genetic engineering, enhancing the signaling and recognition process between legumes and rhizobia (Olivares et al., 2013; Roy et al. 2020).
It is important to note that the effectiveness of these strategies can vary depending on factors such as soil type, climate, legume species, and management practices. Therefore, it is advisable to adapt these strategies based on local conditions and consult with agricultural experts for specific recommendations.
In Line 970, please the author check the “Reference” format. The format of “Reference” is inconsistent. Please check them.
Yes, all the references format has been corrected and become consistent
Reviewer 4 Report
Comments and Suggestions for Authors
The manuscript “Strategies to enhance Rhizobium -legume symbiosis and reduce nitrogen fertilizer for climate change mitigation” by Abd-Alla and colleagues presents and discusses the impact that nitrogen fertilizers have on the symbiosis between legumes and rhizobia. The authors present several aspects of the symbiotic process, from signaling to nitrogenase activity, which are affected by excessive use of nitrogen fertilizers. Furthermore, the authors present alternatives to increase the efficiency of the symbiosis and thus reduce the use of nitrogen fertilizers, which can contribute to sustainable agriculture and minimize environmental impact.
The article is well written and reads well. The article is well structured and presents the necessary sections for the purpose of this work. However, mitigation strategies are poorly detailed and without the support of studies that demonstrate their viability. Therefore, I recommend that authors present results from other studies that support the alternatives they indicate. The references indicated throughout the text are quite old, it would be recommended that the authors replace them with references to more recent works. The use of one or more figures that represent the negative effects of nitrogen fertilizers on symbiosis would be an added value (a picture is worth of 1000 words).
Author Response
Dear Prof DR.
Thank you for your email dated 4-10-2023 and for your valuable comments and suggestions on our manuscript number agriculture-2638150, titled " Enhancing Rhizobium-legume symbiosis and reducing nitrogen fertilizer use are potential options for mitigating climate change."
(Reviewer 4)
Comments and Suggestions for Authors
The manuscript “Strategies to enhance Rhizobium -legume symbiosis and reduce nitrogen fertilizer for climate change mitigation” by Abd-Alla and colleagues presents and discusses the impact that nitrogen fertilizers have on the symbiosis between legumes and rhizobia. The authors present several aspects of the symbiotic process, from signaling to nitrogenase activity, which are affected by excessive use of nitrogen fertilizers. Furthermore, the authors present alternatives to increase the efficiency of the symbiosis and thus reduce the use of nitrogen fertilizers, which can contribute to sustainable agriculture and minimize environmental impact.
The article is well written and reads well. The article is well structured and presents the necessary sections for the purpose of this work.
However, mitigation strategies are poorly detailed and without the support of studies that demonstrate their viability. Therefore, I recommend that authors present results from other studies that support the alternatives they indicate.
Yes, this section has been improved as you can see in text.
- Mitigation Strategies
To mitigate climate change, it is crucial to find sustainable solutions for reducing nitrogen fertilizer use. One promising approach is through the utilization of Rhizobium-legume symbiosis. By harnessing this natural symbiosis, farmers can reduce their reliance on synthetic nitrogen fertilizers. This is significant because the production and application of nitrogen fertilizers contribute to greenhouse gas emissions, particularly nitrous oxide, which is a potent greenhouse gas (Figure 5). To encourage the adoption of this approach, education and outreach programs should be implemented to raise awareness among farmers about the benefits of Rhizobium-legume symbiosis. Additionally, research and development efforts should focus on optimizing the efficiency of nitrogen fixation in legume crops and identifying suitable Rhizobium strains for different soil conditions. Reducing nitrogen fertilizer use through Rhizobium-legume symbiosis is a promising strategy for climate change mitigation (Compant et al., 2010; Olivares et al., 2013). To enhance the symbiotic relationship between Rhizobium and legumes and reduce reliance on nitrogen fertilizers for climate change mitigation, several strategies can be implemented: - Selecting effective rhizobial strains: To enhance nodulation and nitrogen fixation efficiency, it is crucial to carefully select specific rhizobial strains. This can be accomplished by screening and choosing strains that have a higher compatibility with legume plants. This approach brings numerous advantages in addressing climate change, such as decreased fertilizer usage, improved soil health and carbon sequestration, enhanced plant resilience, and economic benefits for farmers (Olivares et al., 2013; Mabrouk et al., 2018; Roy et al. 2020). - Crop rotation and intercropping: Rotate legume crops with non-leguminous crops to break pest and disease cycles and promote nitrogen cycling in the soil. Intercropping legumes with other crops can enhance nutrient cycling and reduce the need for nitrogen fertilizers. - Using cover crops: Planting cover crops, especially leguminous plants, during fallow periods can enhance soil health and increase the availability of nitrogen. (Jensen et al. 2013). These cover crops can fix atmospheric nitrogen, making it accessible to subsequent crops (Grover et al. 2023). - Improving soil fertility: Employ practices such as organic matter addition, composting, and proper nutrient management to enhance soil fertility (Dubey et al., 2019). Organic fertilizers, crop residue incorporation, and balanced nutrient application can reduce the need for nitrogen fertilization. Soil fertility is crucial for maximizing carbon sequestration, promoting nutrient cycling, improving water retention, supporting biodiversity, and reducing erosion (Oren et al. 2001; Kane and Solutions, 2015). Fertile soils contribute to resilient and sustainable agricultural systems that help mitigate the negative effects of climate change (Elbasiouny et al. 2022). - Proper soil management: Practice good soil management techniques to create a favorable environment for Rhizobium-legume symbiosis and microbial communities (Mukhtar et al., 2023). Maintain optimal soil pH, proper drainage, and avoid excessive use of nitrogen fertilizers, which can hinder nodulation and nitrogen fixation. Healthy soils are crucial for storing carbon and mitigating climate change. When managed sustainably, soils can sequester carbon and reduce greenhouse gas emissions. However, poor soil management and unsustainable agricultural practices can release carbon into the atmosphere, contributing to climate change (Figure 8). The conversion of grassland and forestland to cropland and grazing lands has led to significant soil carbon losses worldwide. By restoring degraded soils and adopting soil conservation practices, we can decrease greenhouse gas emissions, increase carbon sequestration, and build resilience to climate change (Scharlemann et al.,2014). Land use, land-use change, vegetation cover, and soil management strongly influence the processes and emissions of greenhouse gases in the soil. Managing soil organic carbon stocks in the upper soil layers can help reduce greenhouse gas concentrations in the atmosphere (Bayu , 2020). - Optimizing inoculation techniques: Ensure the proper inoculation of legume seeds with efficient rhizobial strains. This involves using appropriate inoculant formulations and ensuring proper seed coating or inoculant application to improve symbiosis establishment (Company et al. 2010). Factors such as bacterial strains, inoculant formulation, application methods, and environmental conditions all play a role in successful inoculation. By improving our understanding and application of these techniques, we can maximize the benefits of symbiotic nitrogen fixation and contribute to climate change mitigation efforts (Shah et al.,2021) - Improving farming practices: Adopt conservation agriculture practices, including reduced tillage, mulching, and water management techniques. These practices enhance soil structure, increase soil organic matter, and reduce nitrogen losses, maximizing the benefits of Rhizobium-legume symbiosis (Jena et al., 2022). By adopting and implementing these improved farming practices, agricultural systems can become more resilient, efficient, and sustainable. This, in turn, helps to reduce the negative impacts of climate change on food production, ecosystems, and the environment. It is crucial to adopt these approaches to preserve nature and its benefits to humanity, while also ensuring the availability of good food at reasonable prices and protecting the environment for our survival (Muhie , 2022). - Integrated nutrient management: Combine Rhizobium inoculation with judicious application of mineral fertilizers to optimize nitrogen availability. This integrated approach ensures adequate nutrient supply while minimizing the use of synthetic fertilizers (Choudhary et al.,2018; Gurjar et al., 2022; Tomar and Bhatnagar, 2022). - Rhizobial inoculant quality control: Verify the effectiveness of commercially available rhizobial inoculants through field trials or consultation with experts (Obando et al., 2019, Jansson, and Hofmockel, 2020; Wong et al., 2022). Use commercially available inoculants or isolate local strains proven to be effective in your specific region. Castellano-Hinojosa et al. (2022) research findings indicate that native rhizobia have a greater positive impact on plant growth, nitrogen fixation, and reduction of greenhouse emissions in sunnhemp crops within Florida citrus orchards, compared to commercial rhizobia inoculants (Woliy et al.,2019). Maintain proper storage conditions, follow application instructions, and use fresh inoculants to maximize efficacy. - Genetic improvement: Employ breeding programs to develop legume cultivars with improved compatibility with specific Rhizobium strains. This can be achieved through marker-assisted selection or genetic engineering, enhancing the signaling and recognition process between legumes and rhizobia (Olivares et al., 2013; Roy et al. 2020).
It is important to note that the effectiveness of these strategies can vary depending on factors such as soil type, climate, legume species, and management practices. Therefore, it is advisable to adapt these strategies based on local conditions and consult with agricultural experts for specific recommendations.
The references indicated throughout the text are quite old, it would be recommended that the authors replace them with references to more recent works.
Yes, most of old reference has been deleted and recent references has been included.
The use of one or more figures that represent the negative effects of nitrogen fertilizers on symbiosis would be an added value (a picture is worth of 1000 words).
Yes, I agree with your suggestion and 8 figures has been included.
Once again, we sincerely appreciate your time and effort in reviewing our manuscript, and we look forward to your positive response.
Thank you and best regards,
Sincerely yours
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
I don't think that the figures 4-6 in the revised version are necessary, since these data sourced from previous literature, rather than your own study work.
Author Response
Dear Prof Dr. (Reviewers)
We would like to express our sincere gratitude for your invaluable effort and time dedicated to editing the current manuscript. Thanks to your expertise and guidance, the manuscript has undergone significant improvements.
Your meticulous review and insightful suggestions have undoubtedly enhanced the quality and clarity of our work. We truly appreciate the thoughtful feedback and constructive criticism you provided, which have been instrumental in refining our research.
Once again, we would like to extend our heartfelt thanks for your dedication and commitment to reviewing our manuscript.
Thank you very much for your continued support.
Reviewer 1,
I don't think that the figures 4-6 in the revised version are necessary, since these data sourced from previous literature, rather than your own study work.
Yes, I agree. Figures 4-6 have been deleted, although these data are from my previous publication (Abdel Wahab, A.M., Zahran, H.H., and Abd-Alla, M.H., 1996. Root-hair infection and nodulation of four grain legumes as affected by the form and application time of nitrogen fertilizer. Folia Microbiologica, 41, 303-308).
(Reviewer 2)
I thank the authors for responding to the comments and considering the suggestions in this new version of the manuscript, which I believe have contributed to a significant improvement in its scientific quality.
Thank you very much.
Once again, we sincerely appreciate your time and effort in reviewing our manuscript, and we look forward to your positive response.
Sincerely yours
Prof Dr Abdel-Wahab Elsadek El-Enany
Reviewer 4 Report
Comments and Suggestions for Authors
I thank the authors for responding to the comments and considering the suggestions in this new version of the manuscript, which I believe have contributed to a significant improvement in its scientific quality.
Author Response
Dear Prof Dr. (Reviewers)
We would like to express our sincere gratitude for your invaluable effort and time dedicated to editing the current manuscript. Thanks to your expertise and guidance, the manuscript has undergone significant improvements.
Your meticulous review and insightful suggestions have undoubtedly enhanced the quality and clarity of our work. We truly appreciate the thoughtful feedback and constructive criticism you provided, which have been instrumental in refining our research.
Once again, we would like to extend our heartfelt thanks for your dedication and commitment to reviewing our manuscript.
Thank you very much for your continued support.
Reviewer 1,
I don't think that the figures 4-6 in the revised version are necessary, since these data sourced from previous literature, rather than your own study work.
Yes, I agree. Figures 4-6 have been deleted, although these data are from my previous publication (Abdel Wahab, A.M., Zahran, H.H., and Abd-Alla, M.H., 1996. Root-hair infection and nodulation of four grain legumes as affected by the form and application time of nitrogen fertilizer. Folia Microbiologica, 41, 303-308).
