Chitosan Application Improves the Growth and Physiological Parameters of Tomato Crops

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

The authors have improved the manuscript significantly. However, there are still a few thigs that should be addressed:

1) Line 100-103 „It was not applied as a suspension, but as a colloidal solution [22]. In addition, the chitosan powder has an average size <100 μm according to supplier specifications.“ Should be changed to „It was applied as a colloidal solution [22].“ The second sentence ca be deleted since the chitosan was first dissolved in acetic acid and thus the original particle size is of minor relevance (that would be important if the product was used as a suspension but the chitosan was applied after dissolution in 1% HAc and subsequent partial neutralisation).

Line 156 and Table 2: the number of fruits harvested at the end of the experiment is a quite useless parameter. The authors should give the total umber of fruits that was harvested per plant over the entire experiment. If this parameter is not available they should simply delete the values.

Line 260: the authors must explain how they calculated the yield per ha from the yield per plant, i.e. the formula should be given in the Materials and Methods section.

Author Response

Reviewer 1

1) Line 100-103 „It was not applied as a suspension, but as a colloidal solution [22]. In addition, the chitosan powder has an average size <100 μm according to supplier specifications.“ Should be changed to „It was applied as a colloidal solution [22].“ The second sentence ca be deleted since the chitosan was first dissolved in acetic acid and thus the original particle size is of minor relevance (that would be important if the product was used as a suspension but the chitosan was applied after dissolution in 1% HAc and subsequent partial neutralisation).

 

We are agreed

Line 120

The sentence “It was not applied as a suspension, but as a colloidal solution [22]” was changed by It was applied as a colloidal solution [22]

 

Line 156 and Table 2: the number of fruits harvested at the end of the experiment is a quite useless parameter. The authors should give the total number of fruits that was harvested per plant over the entire experiment. If this parameter is not available they should simply delete the values.

 

Thank you for the comment and suggestion. With that number of fruits harvested, the production was estimated according to the equation that we added in the materials and methods session, for this reason we consider that the following should be presented.  We checked and calculated the production based on this equation shown below and the results were corrected see table 2.

 

Line 260: the authors must explain how they calculated the yield per ha from the yield per plant, i.e. the formula should be given in the Materials and Methods section.

 

The plants were planted at a distance of 0.3 x 0.6 m, this allowed us to know the density of plants in one hectare (555556 plants).

 

 

Line 180-184 we added the sentence

Fifteen plants were evaluated in each treatment and the yield (kg ha-1) was extrapolated according to the following equation:

 

Yield = number of fruits harvest × average weight of fruit (gr) × 55556 /1000          (1)

 

where 55556 represents the number of tomato plants in one hectare.

 

 

 

 

 

Reviewer 1

1) Line 100-103 „It was not applied as a suspension, but as a colloidal solution [22]. In addition, the chitosan powder has an average size <100 μm according to supplier specifications.“ Should be changed to „It was applied as a colloidal solution [22].“ The second sentence ca be deleted since the chitosan was first dissolved in acetic acid and thus the original particle size is of minor relevance (that would be important if the product was used as a suspension but the chitosan was applied after dissolution in 1% HAc and subsequent partial neutralisation).

 

We are agreed

Line 120

The sentence “It was not applied as a suspension, but as a colloidal solution [22]” was changed by It was applied as a colloidal solution [22]

 

Line 156 and Table 2: the number of fruits harvested at the end of the experiment is a quite useless parameter. The authors should give the total number of fruits that was harvested per plant over the entire experiment. If this parameter is not available they should simply delete the values.

 

Thank you for the comment and suggestion. With that number of fruits harvested, the production was estimated according to the equation that we added in the materials and methods session, for this reason we consider that the following should be presented.  We checked and calculated the production based on this equation shown below and the results were corrected see table 2.

 

Line 260: the authors must explain how they calculated the yield per ha from the yield per plant, i.e. the formula should be given in the Materials and Methods section.

 

The plants were planted at a distance of 0.3 x 0.6 m, this allowed us to know the density of plants in one hectare (555556 plants).

 

 

Line 180-184 we added the sentence

Fifteen plants were evaluated in each treatment and the yield (kg ha-1) was extrapolated according to the following equation:

 

Yield = number of fruits harvest × average weight of fruit (gr) × 55556 /1000          (1)

 

where 55556 represents the number of tomato plants in one hectare.

 

 

 

 

 

 

Reviewer 1

1) Line 100-103 „It was not applied as a suspension, but as a colloidal solution [22]. In addition, the chitosan powder has an average size <100 μm according to supplier specifications.“ Should be changed to „It was applied as a colloidal solution [22].“ The second sentence ca be deleted since the chitosan was first dissolved in acetic acid and thus the original particle size is of minor relevance (that would be important if the product was used as a suspension but the chitosan was applied after dissolution in 1% HAc and subsequent partial neutralisation).

 

We are agreed

Line 120

The sentence “It was not applied as a suspension, but as a colloidal solution [22]” was changed by It was applied as a colloidal solution [22]

 

Line 156 and Table 2: the number of fruits harvested at the end of the experiment is a quite useless parameter. The authors should give the total number of fruits that was harvested per plant over the entire experiment. If this parameter is not available they should simply delete the values.

 

Thank you for the comment and suggestion. With that number of fruits harvested, the production was estimated according to the equation that we added in the materials and methods session, for this reason we consider that the following should be presented.  We checked and calculated the production based on this equation shown below and the results were corrected see table 2.

 

Line 260: the authors must explain how they calculated the yield per ha from the yield per plant, i.e. the formula should be given in the Materials and Methods section.

 

The plants were planted at a distance of 0.3 x 0.6 m, this allowed us to know the density of plants in one hectare (555556 plants).

 

 

Line 180-184 we added the sentence

Fifteen plants were evaluated in each treatment and the yield (kg ha-1) was extrapolated according to the following equation:

 

Yield = number of fruits harvest × average weight of fruit (gr) × 55556 /1000          (1)

 

where 55556 represents the number of tomato plants in one hectare.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

This study explores the effects of chitosan on crop physiological growth, yield, quality, and other indicators. The topic is very interesting, involving many indicators, and the workload is sufficient. But there are issues in this manuscript that are worth revising, and the current status is still some way from meeting the requirements of this journal. The specific issues can be found below, and of course, the issues are not limited to these. The author is requested to carefully review the paper revisions.

1. Line 23-26: It is not necessary to list all indicators in the summary. Here, the impact results of the treatment on the indicators are directly given, and necessary data is listed.The same applies to lines 26-28. Please provide specific data to clarify the promotion effect.In addition, the description of the abstract results section is very vague and cannot obtain information related to this study, so it needs to be rewritten.
2. Line 23-26: It is not necessary to list all indicators in the summary. Here, the impact results of the treatment on the indicators are directly given, and necessary data is listed.The same applies to lines 26-28. Please provide specific data to clarify the promotion effect.In addition, the description of the abstract results section is very vague and cannot obtain information related to this study, so it needs to be rewritten.
3. The introduction has too many paragraphs, many of which are unnecessary and reduce the readability of the article. The author needs to further summarize. 

   Line 42: The author mentioned "synthetic fertilizers and pests", so chitosan belongs to synthetic fertilizers? Or pests?

4. Line 58-81: The author listed the positive effects of chitosan on crop growth, indicating that there have been many related studies. So, what is the difference between this study and previous research? What are the current issues that need to be addressed in the research of chitosan? The author needs to emphasize the innovation and practical significance of this study in the introduction.
5. Line 113 and Line 141: After 120 days of crop growth after harvesting, why choose to analyze physiological growth parameters on the 50th day?.
6. Line 149: Please provide the time for calculating the number of fruits (days after transplanting)
7.  Line 260-261: In fact, crop yield shows a trend of first increasing, then decreasing, and then increasing with the increase of chitosan dosage. The difference between treatments is not significant, but this pattern should not be ignored. In addition, the yield of both tomatoes decreased at a dosage of 1000 mg/L. What is the reason for this?
8. In Figure 2A, the error bars of some data are very large, resulting in data with significant differences but insignificant differences. Large errors may result in data not passing the homogeneity of variance test. Please optimize the data processing method and improve the quality of the data.
9.  Line 168: Please supplement the data collection time according to Line 307, and clarify which data was collected in 38 days and 58 days respectively.

10. Figure 7 contains a large number of abbreviations, but lacks annotations, resulting in poor readability of the figure. Please supplement. In addition, figure “a and b” essentially have the same function and do not need to appear simultaneously.

11. Figure 8 seems to have little significance in this article. The author also mentioned that the result of the image modification is the same as Figure 7b, which does not provide more useful information. It is recommended to delete it.

12. The discussion section has the same problem as the introduction, which is that there are too many paragraphs. And the content of different paragraphs in the discussion is relatively independent, without a clear theme; There is no logic between paragraphs, resulting in poor readability. The author needs to further clarify the discussion ideas and organically integrate the literature, rather than just frantically listing the literature.

13. The conclusion section should provide a detailed explanation of the specific findings of this study, while the text in Line 548-555 is very general and the conclusion section is not suitable for citing references. The author should further summarize the conclusions of this study, rather than proving the existing views of others. Please ask the author to rewrite the conclusion.

Author Response

 

Review 2

Line 23-26: It is not necessary to list all indicators in the summary. Here, the impact results of the treatment on the indicators are directly given, and necessary data is listed. The same applies to lines 26-28. Please provide specific data to clarify the promotion effect. In addition, the description of the abstract results section is very vague and cannot obtain information related to this study, so it needs to be rewritten.

We agreed, the list of all indicators in the summary was left out.

The  summary was  rewritten

 

Line18-32

Tomato crops are treated with high concentrations of synthetic fertilizers and insecticides to increase yields, but the careless use of these chemicals harms the environment, human health, and affects plant pathogen resistance. The effect of foliar spray of three concentrations of chitosan (500, 1000, and 2000 mg L-1) on plant growth, yield, fruit quality and physiological performance in two tomato varieties (Candela F1 and Floradade) was studied. Physiological traits such as photosynthesis, chlorophyll content, and leaf area index of the plants were positively affected by chitosan, an effective compound that biostimulates growth with increases in biomass of organs with respect to the control treatment. Chitosan also improved tomato quality such as increases in polyphenols, antioxidant capacity, flavonoids, carotenoids, vitamin C,  and total soluble solids in both tomato varieties. Finally, yield increased by 76.4 % and 65.4 % in Floradade and Candela F1, respectively. The responses of tomato plants to chitosan application were different depending on the variety evaluated, indicating a differential response to the biostimulant. The use of chitosan in agriculture is a tool that has no negative effects on plants and the environment and can increase the productive capacity of tomato plants.

 

The introduction has too many paragraphs, many of which are unnecessary and reduce the readability of the article. The author needs to further summarize.

 

Thanks for the comment. The number of paragraphs was reduced and some sentences were edited and others were eliminated. The introduction was improved

 

Line 42: The author mentioned "synthetic fertilizers and pests", so chitosan belongs to synthetic fertilizers? Or pests? 1.221.461

 

Chitosan is not a synthetic fertilizer, in fact is  a natural polysaccharide derived from chitin, a major component of crustacean shells (like shrimp and crabs) and fungal cell walls. In other words, chitosan it is a naturally occurring biopolymer made from chitin. Chitosan is used in agriculture for a number of reasons, including as promoting plant growth, controlling pests and diseases, and acting as a fertilizer carrier. It is not a synthetic fertilizer in and of itself, although it can be used with some of them.

 

Line 58-81: The author listed the positive effects of chitosan on crop growth, indicating that there have been many related studies. So, what is the difference between this study and previous research? What are the current issues that need to be addressed in the research of

chitosan? The author needs to emphasize the innovation and practical significance of this study in the introduction.

The foliar application of nanoparticles is a relatively new technique that is leading to precision agriculture and indeed there are many studies carried out. However, in this study we want to corroborate its effect on physiological, morphological, production and fruit quality variables, not always there is a positive effect of the NPs, this will depend on many factors such as the species, variety or genotype evaluated. In our case we see that depending on the variety there was a different effect on the responses of the evaluated variables to foliar spraying with SiO₂ NPs.

 

We added on Line 76-78 a new sentence

Numerous studies have documented the beneficial effects of chitosan on crop growth.  Nevertheless not much research has been done on how chitosan affects tomato hybrids (Candela F1) and pure variety (Floradade).

 

 

Line 113 and Line 141: After 120 days of crop growth after harvesting, why choose to analyze physiological growth parameters on the 50th day?.

 

We decided to measure during fruit formation, at 38 days and when the fruits were already mature and well formed (58 day), rather than at 120 days because the crop was already exhibiting signs of senescence. This is because the crop is in full development and the first fruits appear between 30 and 40 days.

 

Line 149: Please provide the time for calculating the number of fruits (days after transplanting)

 

We provide the information Line 169-170 “The fruits appear between 30 and 40, the data of the clusters and fruits were taken 45 days after transplanting”.

 

Line 260-261: In fact, crop yield shows a trend of first increasing, then decreasing, and then increasing with the increase of chitosan dosage. The difference between treatments is not significant, but this pattern should not be ignored. In addition, the yield of both tomatoes decreased at a dosage of 1000 mg/L. What is the reason for this?

 

We agree In order not to ignore this fact, a new sentence was written o line 289-290

" Furthermore, both tomato yields declined at 1000 mg/L, with Floradade experiencing a more pronounced decrease than Candela F1”

 

In fertilization, it is often observed that low yields occur at medium doses, while low and high doses can generate higher yields. This is due to several factors, including nutrient use efficiency of plants, soil properties and nutrient interactions. However, and to be honest we do not know what was the reason for this yield decrease at 1000mg L^-1 of chitosan.  Anything I can comment on could be speculative.

.-Low doses

In soils with low fertility, a low dose of fertilizer may be sufficient to meet basic plant needs, allowing for initial growth and root development. However, as the crop progresses, the demand for nutrients increases and the low dose may become limiting, resulting in lower yields compared to higher doses.

 

.- Interaction between nutrients:

The relationship between different nutrients in the soil is also important. An excess of one nutrient can affect the absorption or utilization of others, creating nutritional imbalances and reducing yield. For example, a high concentration of nitrogen can hinder the absorption of other nutrients such as phosphorus or potassium, affecting plant development.

 

We think that the relationship between fertilizer dose and yield is not linear. It is important to consider soil properties, nutrient use efficiency, nutrient interactions and crop-specific needs to determine the optimum fertilizer rate and achieve maximum yield.

 

In Figure 2A, the error bars of some data are very large, resulting in data with significant differences but insignificant differences. Large errors may result in data not passing the homogeneity of variance test. Please optimize the data processing method and improve the quality of the data.

 

Thank you very much to the reviewer for noticing this important detail, indeed we checked the results and for the case of Floradade (2000 mg L^-1) there was an error in the transcription of the data between the Y_am and Y_pm value, it was corrected.

For the Candela F1 variety, the standard error presented was large for two reasons, the first being that it was showing the standard deviation instead of the standard error, and the second that of the three plants evaluated in the treatments (500, 1000 and 2000 mg L-1), two showed relatively low Y_pm values and one high Y_pm. The standard error was corrected, but inevitably the average generated is of the three measurements.

The statistical analysis was performed again and the figure was corrected, finding significant differences between clones.

 

 Line 168: Please supplement the data collection time according to Line 307, and clarify which data was collected in 38 days and 58 days respectively.

 

Line 187-189 we added a new sentence in order to clarify which data were collected  in 38 and 58 days

 

All physiological variables (Ψ_am, Ψ_pm, Gas exchanges, LAI and chlorophyll content) were taken between 38 and 58 days after transplanting, when the crop is in full development and the first fruits appear between 30 and 40 days.

 

 

Figure 7 contains a large number of abbreviations, but lacks annotations, resulting in poor readability of the figure. Please supplement. In addition, figure “a and b” essentially have the same function and do not need to appear simultaneously.

 

We agreed thank you very much for the suggestion

 

In the legend of the figure  7 we write what each abbreviation means.

 

Figure 7. (a) Pearson correlation of the response variables, and (b) Biplot of the treatments and response variables in two tomato varieties (Floradade and Candela F1) treated with chitosan and evaluated at 38 and 58 days after transplanting.

Abbreviations: SPAD 2 (chlorophyll content, 58 DAT); SPAD  (chlorophyll content,  38 DAT); WUE  2 (water use efficiency, 58 DAT); Ci2 (intercellular CO2 concentration, 58 DAT);  GS 2 (stomatal conductance, 58 DAT); E2 (transiration rate, 58 DAT); A2 (net photosynthetic rate, 58 DAT);WUE (water use eficiency, 38 DAT); CI (intercellular CO2 concentration, 38 DAT); GS (stomatal conductance, 38 DAT); E  (transiration rate, 38 DAT); A (net photosynthetic rate, 38 DAT); LAI2 (leaf area index,  58 DAT); LAI  (leaf area index, 38 DAT); PH NOON 2 (Y_pm,  58 DAT); PH AM 2  (Y_am,  58 DAT); PH NOON (Y_pm, 38 DAT); PH AM (Y_am, 38 DAT); SH/R Shoot/Root; ShDW (Shoot Dry Weigh); LDW (Leaf Dry Weight); SDW (Stem Dry Weight); RDW (Root Dry Weight); Fruit  yield; FED (Equatorial Diameter of the Fruit); FPD (Polar Diameter of the Fruit); AFW  (Average Fruit Weight); NHF (Number of Harvested Fruits); TC (Total clusters).

 

Figure 8 seems to have little significance in this article. The author also mentioned that the result of the image modification is the same as Figure 7b, which does not provide more useful information. It is recommended to delete it.

 

We agree and thank you for your suggestion, we have eliminated figure 8.

 

The discussion section has the same problem as the introduction, which is that there are too many paragraphs. And the content of different paragraphs in the discussion is relatively independent, without a clear theme; There is no logic between paragraphs, resulting in poor readability. The author needs to further clarify the discussion ideas and organically integrate the literature, rather than just frantically listing the literature.

Thank you very much for the suggestion

We totally agree, we reorganized the paragraphs in a logical order, we eliminated repeated sentences and we consider that now the discussion is better.

The conclusion section should provide a detailed explanation of the specific findings of this study, while the text in Line 548-555 is very general and the conclusion section is not suitable for citing references. The author should further summarize the conclusions of this study, rather than proving the existing views of others. Please ask the author to rewrite the conclusion.

 

This sentence was eliminated “Furthermore, it has been reinforced by high impact references such as [48], who summarize the multiple functions of chitosan as a biopolymer in horticultural crops”.

 

Lines 547-546  new conclusion

According to our study's data, chitosan increased net photosynthetic rate, chlorophyll content, leaf area index (LAI), and biomass, which led to a  considerably improved yields,  demonstrating its efficacy as a biostimulant. Depending on the variety assessed, tomato plants responded differently to the application of chitosan, indicating a variable reaction to the biostimulant. Chitosan is an efficient compound to biostimulate the growth and development of tomato plants, in addition to positively modifying tomato physiology, which can potentially increase the yield of agricultural crops. Therefore, the use of chitosan in agriculture can be a useful tool to increase the productive capacity of crops, with the advantages of being an easily accessible compound and having no negative effects on crops or the environment

 

 

 

 

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

In the manuscript “Chitosan application improves the growth and physiological parameters of tomato crops”, the authors investigated the effects of exogenous chitosan on tomato growth and fruit quality formation. Overall, the manuscript is interesting for readers aimed to increase tomato growth. However, there are still some issues that need to be solved.

1. I have doubt whether the statistical analysis of the data is accurate throughout the manuscript. For example, in Table 1, for the “Height” parameter, 130.47±1.9a, 114.27±2.1ab, 125.9±1.8b. I don’t know the evidence why the authors indicated these letters. Please confirm the lowercase letters throughout the manuscript. This is of vital importance.
2. Lines 30-31: the sentence “to biostimulate the growth, positively modified the plants’ physiology, increasing the yield and fruit quality in both varieties of tomato” should be improved.
3. The introduction and discussion parts have too many paragraphs and should be decreased to concentrate the theme that the authors want to express.
4. Why did the authors select two tomato varieties “Floradade” and “Candela F1”? Are there any differences between the two tomato varieties? Is this difference reflected in growth habits, yield and quality or resistance?
5. The overall content of this article is still reflected in the changes in morphological indicators and physiology, but the molecular mechanism of how chitosan affects the growth and quality formation of tomato still needs to be further analyzed. It is suggested to add relevant contents in the discussion section.
6. The conclusion part should reflect the key findings and results of the whole paper, and usually there are no references.

Author Response

Reviewer  3

1. I have doubt whether the statistical analysis of the data is accurate throughout the manuscript. For example, in Table 1, for the “Height” parameter, 130.47±1.9a, 114.27±2.1ab, 125.9±1.8b. I don’t know the evidence why the authors indicated these letters. Please confirm the lowercase letters throughout the manuscript. This is of vital importance.

 

Thank you very much for the reasonable doubt, in fact you were right in table 1, the statistical analysis was performed and the test was applied a posteriori, and lowercase letters were corrected throughout the manuscript. See table 1

 

 

 

1. Lines 30-31: the sentence “to biostimulate the growth, positively modified the plants’ physiology, increasing the yield and fruit quality in both varieties of tomato” should be improved.

We improved the sentence by 

 

Line 23-29

Physiological traits such as photosynthesis, chlorophyll content, and leaf area index of the plants were positively affected by chitosan, an effective compound that biostimu-lates growth with increases in biomass of organs with respect to the control treatment. Chitosan also improved tomato quality such as increases in polyphenols, antioxidant capacity, flavonoids, carotenoids, vitamin C, and total soluble solids in both tomato varieties. Finally, yield increased by 76.4 % and 65.4 % in Floradade and Candela F1, respectively

 

 

3. The introduction and discussion parts have too many paragraphs and should be decreased to concentrate the theme that the authors want to express.

 

 

Thanks for the comment. The number of paragraphs was reduced and some sentences were edited and others were eliminated. Both introduction and discussion were improved

 

 

1. Why did the authors select two tomato varieties “Floradade” and “Candela F1”? Are there any differences between the two tomato varieties? Is this difference reflected in growth habits, yield and quality or resistance?

 

 

Line 111-116we add a new sentence

These two varieties (Floradade and Candela F1) were chosen because they are widely used in Ecuador due to their productivity, vigor, and resistance to disease. Floradade is an open-pollinated variety, whereas Candela F1 is an F1 hybrid. Although Floradade is a well-known and respected variety, Candela F1 offers better traits in terms of vigor, yield, and resistance because it is an F1 hybrid.

 

 

1. The overall content of this article is still reflected in the changes in morphological indicators and physiology, but the molecular mechanism of how chitosan affects the growth and quality formation of tomato still needs to be further analyzed. It is suggested to add relevant contents in the discussion section.

 

 

Although the objective of our work was not to elucidate the molecular mechanism of how chitosan affects tomato growth and quality, we included a sentence in the discussion related to the molecular mechanisms of how chitosan affects tomato growth and quality.

 

Line 530-535 We add a new sentence

In response to the foliar application of chitosan both tomato varieties, showed a higher yield better their fruit quality which was associated with higher net photosyn-thetic rate, chlorophyll content and LAI, which explained the increase tomato crop growth and development. Studies have been conducted on the molecular mechanisms of how chitosan affects plant growth and development [68]. However, regard that more research with this approach and its effect on tomato quality are still needed and should be further analyzed

 

Also we included a new references   line 750-751

Lopez-Moya, F.; Suarez-Fernandez, M.; Lopez-Llorca, L.V. Molecular Mechanisms of Chitosan Interactions with Fungi and Plants. Int. J. Mol. Sci. 2019, 20, 332. https://doi.org/10.3390/ijms20020332

 

1. The conclusion part should reflect the key findings and results of the whole paper, and usually there are no references.

 

 We agreed, thanks for the suggestion. we rewrote the conclusion and deleted the reference.

This sentence was eliminated “Furthermore, it has been reinforced by high impact references such as [48], who summarize the multiple functions of chitosan as a biopolymer in horticultural crops”.

 

Lines 547-546  new conclusion

According to our study's data, chitosan increased net photosynthetic rate, chlorophyll content, leaf area index (LAI), and biomass, which led to a  considerably improved yields,  demonstrating its efficacy as a biostimulant. Depending on the variety assessed, tomato plants responded differently to the application of chitosan, indicating a variable reaction to the biostimulant. Chitosan is an efficient compound to biostimulate the growth and development of tomato plants, in addition to positively modifying tomato physiology, which can potentially increase the yield of agricultural crops. Therefore, the use of chitosan in agriculture can be a useful tool to increase the productive capacity of crops, with the advantages of being an easily accessible compound and having no negative effects on crops or the environment

 

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

I am pleased to receive the revised manuscript once again. The author has conducted active research on the manuscript, but there are still some issues worth revising. The specific issues are as follows:

1. The author emphasizes that the background of this study includes insecticides, but this study does not mention any research on insecticides. Does chitosan have insecticidal properties? The author's explanation of the properties or functions of chitosan is insufficient, and only the effects of chitosan on physiological growth have been studied. Suggest deleting the description about insecticides.
2. In Keywords, 'correlation' is not suitable as a keyword and has no meaning.
3. Lines 77-84 and 92-99 are repeated.
4. Line 184-185: Formula (1) seems to display an error（55556）.
5. Line 287：“the yield increased from 91452 kg ha-1 in the control to 51844 kg ha-1”， The yield of the two treatments is written in reverse.

Author Response

1. The author emphasizes that the background of this study includes insecticides, but this study does not mention any research on insecticides. Does chitosan have insecticidal properties? The author's explanation of the properties or functions of chitosan is insufficient, and only the effects of chitosan on physiological growth have been studied. Suggest deleting the description about insecticides.

 

Many thanks to the reviewer for his suggestion. But with all due respect, we disagree. We only mentioned “insecticides” in the abstract once, to put in context the damage that pesticides and synthetic fertilizers cause to the environment, to health and the increase of pest resistance. As the reviewer rightly points out, the objective of the work was not to know the effect of chitosan as an insecticide.

 

Yes, chitosan does have insecticidal properties. Although chitosan is more well-known for its antibacterial and plant-growth-promoting qualities, it does also have insecticidal properties. Research has shown that it has an insecticidal effect, but one that is less direct than that of other pesticides.

 

 

1. In Keywords, 'correlation' is not suitable as a keyword and has no meaning.

 

In keywords   Correlation was change by chitin

 

1. Lines 77-84 and 92-99 are repeated.

 

We agree, the sentences repeat was deleted

 

1. Line 184-185: Formula (1) seems to display an error（55556.

 

It was not a mistake, 55556 corresponds to the number of plants that would be planted in one hectare (10000 m2) a distance of 0.3 x 0.6 m (0.18 m2).   So, 10000/0.18 =55555.56

 

 

5. Line 287：“the yield increased from 91452 kg ha-1 in the control to 51844 kg ha-1”， The yield of the two treatments is written in reverse.

 

We agree.  This mistake was corrected

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1.At line 228, authors state that " In the Candela F1 variety, there were no significant differences between the control and chitosan treatments for this variable (Table 2)." Please give some discussion about this statements.

2. At line 231, authors state that "In the number of fruits harvested, the Floradade variety showed no differences between the control treatment and the different concentrations of chitosan" Please give some discussions about this statements.

3.At line 439, authors state that ". In our study, no significant differences in stomatal conductance were observed the chitosan treatments and the control; these results may be due to the fact that there was no water deficiency in the experimental environment" Please give some reference about this statements.

4.At line 480, authors state that ". Chitosan is an efficient compound to biostimulate the growth and development of tomato plants, in addition to positively modifying tomato physiology, which can potentially increase the yield of agricultural crops." Please show the evidence about "Chitosan is an efficient compound to biostimulate the growth and development of tomato plants" in this manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript describes the impact of chitosan application on physiological parameters of two tomato cultivars. The authors claim that chitosan treatment affects plat growth, vigour, photosynthesis and yield in a positive way.

However, I have several concerns:

1) The source of chitosan was not stated. In addition, chitosan is a water insoluble polymer. Thus, I guess a suspension was applied. However, suspensions are difficult to apply; how did the authors ensure that the correct amounts were applied? How quick do the chitosan particles settle in the solution? What was the particle size of the chitosan used?

2) The authors report the yield in t/ha but it remains elusive hoe that was calculated. The authors should also mention the yield per plant.

3) With respect to yield it must be mentioned that the experiment had a duration of only 120 days. This is very short since tomatoes are usually cultivated longer. However, this depends of course on the cultivar. Wat the usual growth duration for this two cultivars?

4) What is the meaning of “harvested fruits”? Since the numbers are small I guess it is not the total umber of fruits harvested during the whole experiment. However, exactly that (total numbers during the experiment) should be given. The umber on a certain date is random.

5) I am surprised that the percentage of defective fruits, e.g. such with ed blossom rot, is not given.

6) The major drawback of the study is that no fruit quality data (sugar content, titratable acidity, pH,…) were recorded.

Reviewer 3 Report

Comments and Suggestions for Authors

The purpose of this study was to confirm how to increase tomato productivity while preventing pathogens using chitosan to solve various environmental problems caused by pesticides used to maintain tomato productivity. However, in this study manuscript, we did not conduct any experiments on microbial pathogens and only investigated the response and growth of plants when chitosan was treated. That is, in order to confirm the prevention of pathogens through chitosan treatment on tomatoes, it was necessary to inoculate the pathogens and check the disease severity of the control group and the treatment group. However, this study does not contain such information. However, in order to confirm simple matters such as growth and chlorophyll changes, it would have been necessary to compare chitosan with other organic fertilizers to highlight its effectiveness. Therefore, it is judged that the experimental design itself is problematic from the purpose of this study. In order to emphasize the disease prevention effect of chitosan, it is necessary to inoculate the disease and examine the growth, and if only the growth effect is to be examined, the effect of the fertilizer should be investigated by treating other organic fertilizers.