Sustainable Olive Culture under Climate Change: The Potential of Biostimulants

Round 1

Reviewer 1 Report

Celeste Dias et al., have written a review entitled "Sustainable olive cultivation under climate change: the potential of biostimulants". It is a very interesting article because the global inputs of agrochemicals and irrigation have increased, making it crucial to find sustainable alternatives to maintain high productivity under the current climate. Especially in crops such as the olive tree, taking into account that it is one of the most important economic sectors in the Mediterranean area.

The review is well structured in four sections. A brief introduction is made on the current situation of olive cultivation in the Mediterranean area and on the impact of climatic changes on olive yield. Finally, the most common biostimulants and the current use of biostimulants in olive crops are explained. So, I consider the article to have achieved its goal (lines 59-61).

However, I would like to recommend some small changes:

-  -  Irrigation is not mention in article 1: They say: “The ever-increasing population exhibits pressure on arable land to increase crop yield, leading to indiscriminate use of chemical fertilizers, insecticides, pesticides, etc. by the farmers”. Please correct line 45.

-        -  In lines 83-87, they say: “EU Mediterranean countries, with Spain and Italy, Greece and Portugal being top producers. Europe also holds a major share of global consumption, being Spain, Italy, Greece, and France in the top consuming countries (EC 2021). Table 1 shows the production of olives for olive oil in the last years”. Please, complete Table 1 with information on consumption, not just information on the production of olives for olive oil. In this way, in this new table, it will be possible to see all the information explained in lines 83-87.

-       -   There are some areas suffering from drought in the Mediterranean area, as it is explained in line 166. In this case olive production demands irrigation. Please, include the average volumen of irrigation water used in these areas in order to see the importance of this fact. Issues related to irrigation are explained several times in the article, but current data on the average volume of irrigation water is not included. I believe this information is crucial to understanding the problem of increased irrigation, taking into account that this is a review.

Author Response

We would like to acknowledge the valuable comments, remarks and suggestions made by the reviewers that helped us to improve the quality of the manuscript. We corrected and marked in yellow colour the changes made in the manuscript suggested by the Reviewers. 

Response to comments (Reviewer 1): 

Comment:  Irrigation is not mention in article 1: They say: “The ever-increasing population exhibits pressure on arable land to increase crop yield, leading to indiscriminate use of chemical fertilizers, insecticides, pesticides, etc. by the farmers”. Please correct line 45.

Response: We corrected the sentence. Please see pg. 1 of the new version of the manuscript.

Comment:  In lines 83-87, they say: “EU Mediterranean countries, with Spain and Italy, Greece and Portugal being top producers. Europe also holds a major share of global consumption, being Spain, Italy, Greece, and France in the top consuming countries (EC 2021). Table 1 shows the production of olives for olive oil in the last years”. Please, complete Table 1 with information on consumption, not just information on the production of olives for olive oil. In this way, in this new table, it will be possible to see all the information explained in lines 83-87.

Response: Thank you for the suggestion. We add information concerning the percentage of olive oil consumption in the Mediterranean countries in table 1. Moreover, in the text (pg. 3 line 107) we also add information about the percentage of oil consumed in Europe.

Comment: There are some areas suffering from drought in the Mediterranean area, as it is explained in line 166. In this case olive production demands irrigation. Please, include the average volumen of irrigation water used in these areas in order to see the importance of this fact. Issues related to irrigation are explained several times in the article, but current data on the average volume of irrigation water is not included. I believe this information is crucial to understanding the problem of increased irrigation, taking into account that this is a review.

Response: We understand the importance of these data. The data available in the literature is very scattered and not specific (it depends on the area, age of the plants, cultivar, etc). We add some information concerning the olive water requirements for intensive culture (please see pg.3, lines 121-122).

Reviewer 2 Report

Dear Authors:

I'd want to express my gratitude for allowing me to review this manuscript. The manuscript needs the following adjustments:

General Comments:

The impact of bio-stimulants on the removal or mitigation of heavy metals is not discussed by the authors.

There is no information on the typical activities of bio-stimulants.

The authors briefly discuss the advantages of bio-stimulants. By citing certain examples from published papers, the authors should describe the mechanistic effect of bio stimulants under both normal and stressful settings.

The composition of the olive plant's oil is its most crucial component, however there is no information on how bio-stimulation affects the oil profile, particularly how much unsaturated fatty acid accumulates.

Specific Comments:

Abstract:

This paragraph is poorly written. The following details should be briefly provided by the authors:

Climate change's impact and consequences on plant growth, productivity, and quality

Abiotic and biotic stress' impact on a plant's growth, productivity, and quality

Types of bio stimulation and its function in reducing biotic and abiotic stress

Aim of the study

Introduction

The authors should provide a few sentences comparing the effects of agrochemicals and biofertilizers or bio-stimulants on plants and the environment in this part.

The authors ought to include a section on the olive plant's botanical description.

L75-L81: This paragraph requires references.

L82-87: This paragraph requires references.

L65 (section 2. Olive tree and culture systems): The authors ought to include a few phrases describing the nutritional benefits of olives.

L113: The majority of the information in this area is related to the drought stress. The impact of salinity on olive growth, productivity, and quality should be discussed more by the authors.

L115: There should be some quality information of oil included.

L141-:151:  These lines ought to be eliminated because they contain repetitive sentences.

L152: The authors should provide general techniques for enhancing olive culture in the face of climate change.

L150-161: These phrases need to be deleted.

L181-193: These sentences require some references.

L202: Types of bio-stimulants: The authors should describe all kinds of bio stimulants with examples in this section.

L221-224: These sentences should delete

L225-227: Because the authors, as shown in the abstract, demonstrated the benefits of seaweeds in a general manner and were not specifically focused on the olive plants, they should elaborate on this statement by providing some examples of using seaweeds as bio-stimulants under normal and stressful conditions, particularly for olive plants. The authors should use some examples of olive plants that have had seaweed applications to demonstrate the advantages of seaweeds for olive plant growth, yield, and quality, particularly for the oil composition profile. Additionally lacking is the action mode.

L234; 4.1.2. Protein hydrolysates: This section also includes details on the protein hydrolysate composition. It is not known how protein hydrolysates work

L251-256: The authors should provide examples to illustrate this section.

L258: 4.1.4. Microorganisms: Where is the action mode?

L271: 4.1.5. Nanoparticles or nanomaterials: Where is the action mode? Please explain how these bio-stimulations promote growth and production both under normal conditions and under stressful circumstances.

L319 and L377: The impact of bio-stimulants on the quality of oil is not discussed in any of the two parts. The authors need to elaborate on this subject in some detail.

Best regards

 

 

 

 

 

Author Response

We would like to acknowledge the valuable comments, remarks and suggestions made by the reviewers that helped us to improve the quality of the manuscript. We corrected and marked in yellow colour the changes made in the manuscript suggested by the Reviewers. 

Response to the Reviewer 1 comments: 

Comment 1: The impact of bio-stimulants on the removal or mitigation of heavy metals is not discussed by the authors.

Response: We understand the Reviewer comment, and we added some information concerning this issue. Please see pg. 5.

Comment 2: There is no information on the typical activities of bio-stimulants. The authors briefly discuss the advantages of bio-stimulants. By citing certain examples from published papers, the authors should describe the mechanistic effect of bio stimulants under both normal and stressful settings.

Response: We add more information considering the mechanisms activated by biostimulants. Please see pgs. 7- 9.

Comment 3: The composition of the olive plant's oil is its most crucial component, however there is no information on how bio-stimulation affects the oil profile, particularly how much unsaturated fatty acid accumulates.

Response: We added some information concerning the effects of biostimulants on olives and oil yield and quality. Please see pg. 14 (new section: 4.4. Biostimulant effect on olive fruits, oil yield and quality). 

Specific Comments:

Abstract:

Comment: This paragraph is poorly written. The following details should be briefly provided by the authors:

Climate change's impact and consequences on plant growth, productivity, and quality

Abiotic and biotic stress' impact on a plant's growth, productivity, and quality

Types of bio stimulation and its function in reducing biotic and abiotic stress

Aim of the study

Response: We understand the Reviewer comment but considering that the abstract are only 200 words it is not possible to write everything we would like or what we consider important. We add information about the different kind of biostimulants that are studied here, but more details concerning the biostimulants functions are described in the manuscript.

The aim of this study was actually already mentioned previously, but we reformulated the sentence:

In this review, we aim to present different types of biostimulants (e.g. seaweed, protein hydrolysates, humic substances, microorganisms and nanomaterials), their mode of action and benefits in agriculture. We also explore the current state-of-the-art regarding the use of biostimulants in olive culture, and their potential benefits to increase tolerance to (a)biotic challenges.

Overall, we add some points referred by the Reviewer. Please see the new version of the manuscript.

Introduction

Comment: The authors should provide a few sentences comparing the effects of agrochemicals and biofertilizers or bio-stimulants on plants and the environment in this part.

Response: We add this information. Please see pg. 2 of the new version of the manuscript.

Comment: The authors ought to include a section on the olive plant's botanical description.

Response: We add some information concerning this issue. Please see pg. 2.

Comment: L75-L81: This paragraph requires references.

L82-87: This paragraph requires references.

Response: We add references (pgs. 3).

Comment: L65 (section 2. Olive tree and culture systems): The authors ought to include a few phrases describing the nutritional benefits of olives.

Response: We add some information concerning olives nutritional characteristics (pg. 3).

Comment: L113: The majority of the information in this area is related to the drought stress. The impact of salinity on olive growth, productivity, and quality should be discussed more by the authors.

Response: We add information regarding the salinity (pg.4).

Comment: L115: There should be some quality information of oil included.

Response: We add the required information (pg.5).

Comment: L141-:151:  These lines ought to be eliminated because they contain repetitive sentences.

Response: We eliminated this part as suggested.

Comment: L152: The authors should provide general techniques for enhancing olive culture in the face of climate change.

Response: We add some suggestion of techniques to enhance olive culture under climate change (pg. 5).

Comment: L150-161: These phrases need to be deleted.

Response: We eliminated this part as suggested.

Comment: L181-193: These sentences require some references.

Response: The references were added (pg. 6).

Comment: L202: Types of bio-stimulants: The authors should describe all kinds of bio stimulants with examples in this section.

Response: We follow the suggestion:” Biostimulants can be classified according to the source of raw material into several groups, such as seaweed, protein hydrolysates, humic acids, nanoparticle and microorganisms (e.g., bacteria and fungi) [47]”. Please see line 235, pg. 6.

Comment: L221-224: These sentences should delete

Response: We eliminated these sentences as suggested.

Comment: L225-227: Because the authors, as shown in the abstract, demonstrated the benefits of seaweeds in a general manner and were not specifically focused on the olive plants, they should elaborate on this statement by providing some examples of using seaweeds as bio-stimulants under normal and stressful conditions, particularly for olive plants. The authors should use some examples of olive plants that have had seaweed applications to demonstrate the advantages of seaweeds for olive plant growth, yield, and quality, particularly for the oil composition profile. Additionally lacking is the action mode.

L234; 4.1.2. Protein hydrolysates: This section also includes details on the protein hydrolysate composition. It is not known how protein hydrolysates work

 L251-256: The authors should provide examples to illustrate this section.

L258: 4.1.4. Microorganisms: Where is the action mode?

L271: 4.1.5. Nanoparticles or nanomaterials: Where is the action mode? Please explain how these bio-stimulations promote growth and production both under normal conditions and under stressful circumstances.

Response: We followed the suggestion/comments of the Reviewer. Moreover, we add more information concerning the action mode off all biostimulants here studied. Please see pgs. 6-9.

Comment: L319 and L377: The impact of bio-stimulants on the quality of oil is not discussed in any of the two parts. The authors need to elaborate on this subject in some detail.

Response: The impact of biostimulants on oil quality is aborded in section 4.4. Biostimulant effect on olive fruits, oil yield and quality.  Please see pg. 14. 

Reviewer 3 Report

The manuscript is well prepared, they explain almost every point of biostimulant effect on olive culture, but abiotic stress tolerance is less explained, and the section on abiotic stress tolerance needs to improve.

Author Response

We would like to acknowledge the valuable comments, remarks and suggestions made by the reviewers that helped us to improve the quality of the manuscript. We corrected and marked in yellow colour the changes made in the manuscript suggested by the Reviewers.

Response to Reviewer comments (reviewer 3):

Comment 1: The manuscript is well prepared, they explain almost every point of biostimulant effect on olive culture, but abiotic stress tolerance is less explained, and the section on abiotic stress tolerance needs to improve.

Response: We acknowledge the comment of Reviewer. There is not so much information concerning the effects of biostimulants on olive plants under abiotic conditions. We improved this section. Please see the new version of the manuscript (pgs. 12 and 13).

Reviewer 4 Report

The manuscript “Sustainable olive culture under climate change: the potential of biostimulants” by Dias, et al., talking about the potential of biostimulants under varying climatic conditions to help to establish a sustainable olive culture in the Mediterranean region. The MS is well written and thoroughly described and it can find interest among the researchers in this field. However, there are some suggestions that I feel should be incorporated.

The introduction section more looks like an abstract. There is a need to explain little more about the potential of biostimulants and how they can replace other agronomic practices. There is a need to build a relation between the role of biostimulants with the objectives of this review article, supporting by some latest bibliography.

The authors should also provide information about the comparison of biostimulants with other strategies adopted for olive crop improvement against biotic and abiotic stress tolerance. I would suggest drawing this comparison in a separate heading. The following bibliography is suggested to establish this correlation

·         Zahedi, S.M., Hosseini, M.S., Fahadi Hoveizeh, N., Gholami, R., Abdelrahman, M. and Tran, L.S.P., 2021. Exogenous melatonin mitigates salinity‐induced damage in olive seedlings by modulating ion homeostasis, antioxidant defense, and phytohormone balance. Physiologia Plantarum, 173(4), pp.1682-1694.

·         Bashir, M.A., Silvestri, C., Coppa, E., Brunori, E., Cristofori, V., Rugini, E., Ahmad, T., Hafiz, I.A., Abbasi, N.A., Nawaz Shah, M.K. and Astolfi, S., 2021. Response of olive shoots to salinity stress suggests the involvement of sulfur metabolism. Plants, 10(2), p.350.

·         Gucci, R. and Tattini, M., 2010. Salinity tolerance in olive. Horticultural Reviews, Janick, J., (ed.), John Wiley & Sons, Inc.: Oxford, UK, 21, pp.177-214.

·         Silvestri, C., Celletti, S., Cristofori, V., Astolfi, S., Ruggiero, B. and Rugini, E., 2017. Olive (Olea europaea L.) plants transgenic for tobacco osmotin gene are less sensitive to in vitro-induced drought stress. Acta Physiologiae Plantarum, 39(10), pp.1-9.

There is also needed to mention the bibliography related to use of biostimulants in a tabular form

Heading: Olive tree and culture systems

I think this section needs to be a little more synthesized by coordinating the olive culture systems with the objective of the MS, supporting by latest bibliography. I think table 1 is irrelevant here

Section 4: I think the authors should also mention the importance of biostimulants by comparing them with other alternatives like micro/macronutrients or pesticides etc., to support their main objectives of the article. Moreover, this section also needs a tabular representation of these biostimulants by explaining their roles in different crops. I think the authors should mention a little more about the importance of chitosan as a potential biostimulant

At the end the references are not formatted as per the guidelines provided by the journal.

Author Response

We would like to acknowledge the valuable comments, remarks and suggestions made by the reviewers that helped us to improve the quality of the manuscript. We corrected and marked in yellow colour the changes made in the manuscript suggested by the Reviewers.

Response to reviewer 4: 

The manuscript “Sustainable olive culture under climate change: the potential of biostimulants” by Dias, et al., talking about the potential of biostimulants under varying climatic conditions to help to establish a sustainable olive culture in the Mediterranean region. The MS is well written and thoroughly described and it can find interest among the researchers in this field. However, there are some suggestions that I feel should be incorporated.

Comment 1: The introduction section more looks like an abstract. There is a need to explain little more about the potential of biostimulants and how they can replace other agronomic practices. There is a need to build a relation between the role of biostimulants with the objectives of this review article, supporting by some latest bibliography.

Response: We present a general introduction where we only wrote briefly about the theme, since the next sections already described more in detail the several issues regarding biostimulants, climate change/(a)biotic stress and olive culture. We did some changes in this section, please see the new version of the manuscript.

Comment 2: The authors should also provide information about the comparison of biostimulants with other strategies adopted for olive crop improvement against biotic and abiotic stress tolerance. I would suggest drawing this comparison in a separate heading. The following bibliography is suggested to establish this correlation

• Zahedi, S.M., Hosseini, M.S., Fahadi Hoveizeh, N., Gholami, R., Abdelrahman, M. and Tran, L.S.P., 2021. Exogenous melatonin mitigates salinity‐induced damage in olive seedlings by modulating ion homeostasis, antioxidant defense, and phytohormone balance. Physiologia Plantarum, 173(4), pp.1682-1694.
• Bashir, M.A., Silvestri, C., Coppa, E., Brunori, E., Cristofori, V., Rugini, E., Ahmad, T., Hafiz, I.A., Abbasi, N.A., Nawaz Shah, M.K. and Astolfi, S., 2021. Response of olive shoots to salinity stress suggests the involvement of sulfur metabolism. Plants, 10(2), p.350.
• Gucci, R. and Tattini, M., 2010. Salinity tolerance in olive. Horticultural Reviews, Janick, J., (ed.), John Wiley & Sons, Inc.: Oxford, UK, 21, pp.177-214.
• Silvestri, C., Celletti, S., Cristofori, V., Astolfi, S., Ruggiero, B. and Rugini, E., 2017. Olive (Olea europaea L.) plants transgenic for tobacco osmotin gene are less sensitive to in vitro-induced drought stress. Acta Physiologiae Plantarum, 39(10), pp.1-9.

Response: We added this information in a new section of the manuscript (4.3. Other strategies and techniques to improve olive stress performance). Please see pgs. 13 and 14.

Comment: There is also needed to mention the bibliography related to use of biostimulants in a tabular form

Response: We followed the suggestion, and we added a new table  (Table 2), in which we present the work available on the use of biostimulants to control some olive diseases. Since this section of biotic stress (4.2.1.) has a lot of information, we think that the Table will facilitate the understanding.

Comment: Heading: Olive tree and culture systems I think this section needs to be a little more synthesized by coordinating the olive culture systems with the objective of the MS, supporting by latest bibliography. I think table 1 is irrelevant here

Response: We consider this section already synthesized and Table 1 brings a clear overview of the contribution of the Mediterranean area to olives and oil production. Moreover, the information in table 1 is note described in the text, so if we remove the table we lose the opportunity to transmit this information. The importance of Table 1 is also highlighted by Reviewer 1, since he suggested to add even more information concerning the olive oil consumption. (If the Editor consider that we should remove table 1, we will follow this suggestion.)

Comment: Section 4: I think the authors should also mention the importance of biostimulants by comparing them with other alternatives like micro/macronutrients or pesticides etc., to support their main objectives of the article. Moreover, this section also needs a tabular representation of these biostimulants by explaining their roles in different crops. I think the authors should mention a little more about the importance of chitosan as a potential biostimulant

Response: We add some information concerning this issue on pg. 2 (section 1), pg. 5, and pg. 13 (section. 4.3). We also add a new table 2 in section 4.2.1 in which we present the work available on the use of bostimulants to control some olive diseases. We considered that add information about other crops in this section is out of the scope of this study. 

We also understand the potential of chitosan to improve plant performance, but since there is no relevant information on the effects of this compound on olive culture and this Review focus on this species we decide not to add more information.    

Comment: At the end the references are not formatted as per the guidelines provided by the journal.

Response: Thank you. The reference list was rearranged.

 

Round 2

Reviewer 2 Report

No comment

Author Response

The authors thanks the comments and suggestion of the Reviewer that helped us to improve the quality of the manuscript.

 

Reviewer 3 Report

The authors improved the paper and included responses to my questions. 

I recommend that the existing manuscript form be published.

Author Response

The authors thanks the comments and suggestion of the Reviewer that helped us to improve the quality of the manuscript.