Impact of Sodium Hypochlorite Applied as Nutrient Solution Disinfectant on Growth, Nutritional Status, Yield, and Consumer Safety of Tomato (Solanum lycopersicum L.) Fruit Produced in a Soilless Cultivation

Round 1

Reviewer 1 Report

It is a well written manuscript. There is only a doubt because dry weight (dw) and dry matter content (DMC) were used both and what is the unit of DMC. On the other side, it is well known that e.g. NaCl increase soluble solids content and firmness in tomato but you did not evaluate these important quality items of the fruit using chlorine in the NS. At least these information should be mentioned in the text of the paper.

Comments for author File: Comments.pdf

Author Response

General statement

First of all, we sincerely thank Reviewer #1 for his/her time and efforts to review towards the improvement of our work. His/her comments have been very valuable for us. For the answers on every comment/point the reviewer raised please see below and the relevant amendments that have been made in the revised draft. Amendments are indicated with track changes.

 

Reviewer 1

It is a well written manuscript. There is only a doubt because dry weight (dw) and dry matter content (DMC) were used both and what is the unit of DMC. On the other side, it is well known that e.g. NaCl increase soluble solids content and firmness in tomato but you did not evaluate these important quality items of the fruit using chlorine in the NS. At least these information should be mentioned in the text of the paper.

 

Reply to Reviewer 1

Thank you very much for your time and input for the improvement of our manuscript.

First of all, we need to clarify that we have estimated dry matter content as a percentage. For this reason, we have added the “%” as the unit of DMC in the revised document. Also, in line 240 the relevant text has been modified. During the revision process, it has been identified that some more information has been missing from the manuscript but mentioned in the references, so the text has been amended. Finally, the information about the effect of NaCl as salt stress on soluble solids and fruit firmness has been added in the end of Section 2.3 as shown at the revised manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

In the manuscript “Impact of sodium hypochlorite applied as nutrient solution disinfectant on growth, nutritional status, yield, and consumer safety of tomato (Solanum lycopersicum L.) fruit produced in a soilless cultivation" Lykogianni et al. addressed the establishment of a new approach to disinfect recycled soilless cultivation nutrient solution strategy. This strategy led to significant increase in total production of marketable tomato fruits without food safety penalty. They applied different chloride in combination with crop inoculation with pathogens to test the efficiency of chlorine as a disinfectant in soilless nutrient solutions. The paper has a great potential, the findings are significant. The manuscript is well written and easy to follow, and the title and abstract are appropriate for the content of the text.

As explained below, the major concern regarding the experimental data in form of the main figures to be well-founded, title of each table and figure is too long, it is better to give a conclusive title. The details can be described in the figure legends.

Minor concerns:

1: Figure 1 is not easy to interpret. Please used same font and color for each Y-axix title. Also, please add major and minor ticks for both X/Y-axix. Please add title for each bar chart.

2: Numbers in Y-axix of figure 2 should be 0.005, 0.1, 0.15…….

3: Line 212, Duncan’s multiple range test (p< 0.05) gap is missing.

4: Please eighter remove/ add the gap before or after “=” through out the manuscript.

5: Please reformat figure 2.

6: Tomato’s Latin name Solanum lycopersicum should be removed except the first time. 

 

In my opinion, the results of this paper meet the impact and innovation criteria of this journal. This paper will provide a new way to benefit the soilless culture cultivation technique. Finally, I recommend that the paper should be accepted for publication in its present form.

Author Response

General statement

First of all, we sincerely thank Reviewer #2 for his/her time and efforts to review towards the improvement of our work. His/her comments have been very valuable for us. For the answers on every comment/point the reviewer raised please see below and the relevant amendments that have been made in the revised draft. Amendments are indicated with track changes.

 

Reviewer 2

In the manuscript “Impact of sodium hypochlorite applied as nutrient solution disinfectant on growth, nutritional status, yield, and consumer safety of tomato (Solanum lycopersicum L.) fruit produced in a soilless cultivation" Lykogianni et al. addressed the establishment of a new approach to disinfect recycled soilless cultivation nutrient solution strategy. This strategy led to significant increase in total production of marketable tomato fruits without food safety penalty. They applied different chloride in combination with crop inoculation with pathogens to test the efficiency of chlorine as a disinfectant in soilless nutrient solutions. The paper has a great potential, the findings are significant. The manuscript is well written and easy to follow, and the title and abstract are appropriate for the content of the text.

As explained below, the major concern regarding the experimental data in form of the main figures to be well-founded, title of each table and figure is too long, it is better to give a conclusive title. The details can be described in the figure legends.

Reply to Reviewer 2

Thank you for your comment. In the revised version, the text in the legends of most figures/tables has been shortened deleting any unnecessary information or information stated in the text.

 

Reviewer 2

Minor concerns:

1: Figure 1 is not easy to interpret. Please used same font and color for each Y-axix title. Also, please add major and minor ticks for both X/Y-axix. Please add title for each bar chart.

Reply to Reviewer 2

Thank you for your comment. Figure 1 has been amended as you can see in the revised manuscript.

 

Reviewer 2

2: Numbers in Y-axix of figure 2 should be 0.005, 0.1, 0.15…….

Reply to Reviewer 2

Thank you for your comment. Figure 2 has been modified accordingly.

 

Reviewer 2

3: Line 212, Duncan’s multiple range test (p< 0.05) gap is missing.

Reply to Reviewer 2

Thank you for your comment. The text has been amended in the revised manuscript.

 

Reviewer 2

4: Please eighter remove/ add the gap before or after “=” through out the manuscript.

Reply to Reviewer 2

Thank you for your comment. The text has been amended in the revised manuscript.

 

Reviewer 2

5: Please reformat figure 2.

Reply to Reviewer 2

Following the suggestion of Reviewer #2, we reformatted Figure 2 focusing specifically on the presentation of the x-axis.

 

Reviewer 2

6: Tomato’s Latin name Solanum lycopersicum should be removed except the first time.

Reply to Reviewer 2

Thank you for your comment. The text has been amended in the revised manuscript.

 

Reviewer 2

In my opinion, the results of this paper meet the impact and innovation criteria of this journal. This paper will provide a new way to benefit the soilless culture cultivation technique. Finally, I recommend that the paper should be accepted for publication in its present form.

Reply to Reviewer 2

We would like to thank you for your positive feedback. It is our pleasure to have met the standards for publication of Horticulturae.

Author Response File: Author Response.docx

Reviewer 3 Report

The work reported is interesting. However, there are some points that the authors need to address for publication. The points are given below:

1.       The NaOCl was applied in order to investigate its impacts on tomato properties, not its being as a disinfectant, due to the fact that a disinfectant is a chemical that can erase pathogens.

2.       Moreover, the application belongs to chlorine or NaOCl? This needs to be clarified.

3.       It seems that at the lowest investigating concentration of chlorine, the fruit production is the highest, which means the higher chlorine than 2.5 mg/L is, the lower productivity is. Thus, lower concentrations of chlorine should be investigated.

4.       The introduction went too much about soilless cultivation, it should be contained in one paragraph at most, while the disinfectant and the tomato was mentioned too little.

5.        I believe the results of chlorine application depend on the components of the nutrient solution, which, thereby, needs to be specify.

6.       The source of the NaOCl needs to be placed in the chemicals and reagents.

Author Response

General statement

First of all, we sincerely thank Reviewer #3 for his/her time and efforts to review towards the improvement of our work. His/her comments have been very valuable for us. For the answers on every comment/point the reviewer raised please see below and the relevant amendments that have been done in the revised draft. Amendments are indicated with track changes.

 

Reviewer 3

The work reported is interesting. However, there are some points that the authors need to address for publication. The points are given below:

1.The NaOCl was applied in order to investigate its impacts on tomato properties, not its being as a disinfectant, due to the fact that a disinfectant is a chemical that can erase pathogens.

Reply to Reviewer 3

Thank you for your comment. Indeed, in the current study the efficacy of this method against soilborne pathogens was not tested, because the aim of this research was to investigate the safety of the method in terms of crop safety and consumer safety. However, chlorine is lethal to all pathogens if applied at appropriate dosages, which are different for different types of pathogens. Therefore, it is common in the relevant scientific literature to refer to chlorine or NaOCl as a disinfectant. Examples are the papers 8, 33 46, 69, 72 and 78 in the current study.

 

Reviewer 3

2.Moreover, the application belongs to chlorine or NaOCl? This needs to be clarified.

Reply to Reviewer 3

We have used NaOCl as a liquid form of chlorine, because it is a method used most commonly. The details of our practice are mentioned in section 4.1.2. Disinfection methodology. Moreover, in the introduction of our manuscript we note that “the scope of the current work was to investigate the effect of sodium hypochlorite application in the NS supplied to a soilless culture of tomato on plant growth” lines 118-119.

 

Reviewer 3

3.It seems that at the lowest investigating concentration of chlorine, the fruit production is the highest, which means the higher chlorine than 2.5 mg/L is, the lower productivity is. Thus, lower concentrations of chlorine should be investigated.

Reply to Reviewer 3

Thank you very much for your comment. However, the higher chlorine concentrations tested in the current study did not result in significant yield differences compared to the untreated control. Nevertheless, the study of lower concentrations than 2.5 mg L^-1 is an interesting hypothesis, and one to consider in the near future. Hence, we would like to thank you for this interesting idea.

 

Reviewer 3

4.The introduction went too much about soilless cultivation, it should be contained in one paragraph at most, while the disinfectant and the tomato was mentioned too little.

Reply to Reviewer 3

Thank you very much for your time and input for the improvement of our manuscript. We have revised the introduction accordingly.

 

Reviewer 3

5.I believe the results of chlorine application depend on the components of the nutrient solution, which, thereby, needs to be specify.

Reply to Reviewer 3

We would like to note that the components of the nutrient solution are mentioned in detail in supplementary Table 1.

 

Reviewer 3

6.The source of the NaOCl needs to be placed in the chemicals and reagents.

Reply to Reviewer 3

We would like to kindly not accept this suggestion. The “Chemical and Reagents” section of the manuscript (4.5.1) refers only to the chemicals and reagents used for residue analysis. It is our opinion that such a change would be misleading to the readers of the paper.

Author Response File: Author Response.docx