Ethylene and Chitosan Affected the Seed Yield Components of Onion Depending More on the Dose than Timing of Application

Round 1

Reviewer 1 Report

The manuscript by Vecchiotti et al., entitled ‘Ethylene and chitosan differentially affected the seed yield components of onion depending more on the dose rather than timing of application’, evaluating the seed yield components and germination ability of onion seed as affected by the timing and dose of ethylene application and chitosan. The major conclusions are that the ethylene application mostly affected TSW but not yield, whereas high doses of ethylene reduced yields irrespective of the timing of application. Chitosan sustained yield when yield potential was reduced by the 150% RD and such a result was likely due to physical protection from the transpiration.

 

Major concerns：

(1) Less theoretical contribution. This manuscript revealed that the yield depression under high doses of ethylene application mostly occurred through a depression of the flower fertility (measured as number of seeds per inflorescence). However, similar researches have already been reported in application of lower ethylene concentration compared to the present study stimulated yield through an increase of the number of inflorescence per unit area (Singh et al., 1995). In addition, since lower ethylene concentration application has a positive effect on seed yield, why not set a low concentration of ethylene application control?

 

(2) Poor experimental design. Both the effects of ethylene and chitosan application on the seed yield components and germination trend were measured in this study. However, what's the relationship between ethylene and chitosan? Researchers should elaborate more on the reasons why these two types of PGRs were used in this study.

 

To sum up, despite enormous data generated, the findings of the manuscript are correlative. The scientific significance revealed by this manuscript did not reach the average level of Horticulturae at this time.

 

Author Response

#Reviewer_1 (1) Less theoretical contribution. This manuscript revealed that the yield depression under high doses of ethylene application mostly occurred through a depression of the flower fertility (measured as number of seeds per inflorescence). However, similar researches have already been reported in application of lower ethylene concentration compared to the present study stimulated yield through an increase of the number of inflorescence per unit area (Singh et al., 1995).

Authors: we agree the reviewer for his/her comments. So far, we think the reviewer missed the very most of the scientific evaluation of a topic. In particular, the reviewer is citing only one paper (Singh et al., 1995) that, according to his/her evaluation, produced similar results, whereas we showed that the results on this topic were variable. We cited Singh et al. (1995) [our citation n. 32, as can be seen in the discussion section] and showed the differences between our study and the elegant study of these author. Many differences occur, in particular the genotype and environmental conditions were definitely different. Also, the scientific consensus on a topic can’t be built on just one or two studies, but many confirmation and studies are available to build suitable systematic review and systematic metanalyses. In addition, we also showed which other studies had different results compared to our study.

 

#Reviewer_1 In addition, since lower ethylene concentration application has a positive effect on seed yield, why not set a low concentration of ethylene application control?

Authors: we thank the reviewer for this suggestion. Indeed this may be an option for further study. However, as the reviewer may understand, it’s inconvenient to start an experiment in a new, untested area with definitely low applications since this reduces the chances of finding the presence of an effect. In particular, earlier experiments in an areas (such as the one in the present study) apply relatively high concentration (here we used the recommended rate), that these may be lowered in further studies to highlight the crop behaviour.

 

#Reviewer_1 (2) Poor experimental design. Both the effects of ethylene and chitosan application on the seed yield components and germination trend were measured in this study. However, what's the relationship between ethylene and chitosan? Researchers should elaborate more on the reasons why these two types of PGRs were used in this study.

Authors: the relationship between these two treatments were clarified in the introduction. In particular, chitosan can lower the transpiration, whereas ethylene increases it. These contrasting factors are related to both the net primary production of the crop, from the one side, and the ability of the crop to fill the grain, from the other side. This mechanism has been explored in other species. Thanks to the reviewer suggestion, we now pinpointed this mechanism in the introduction. We also included the recent study dealing with the relationship between ethylene and chitosan in tomato (Journal of Plant Physiology 263 (2021) 153461)

 

#Reviewer_1 To sum up, despite enormous data generated, the findings of the manuscript are correlative. The scientific significance revealed by this manuscript did not reach the average level of Horticulturae at this time.

Authors: as we explained above, we disagree that the results are correlative. In particular, there is no other experiment in similar areas and made in similar conditions yielding the same results, also, the similar results from other areas or conditions were obtained through different eco-physiological mechanisms.

Reviewer 2 Report

In the manuscript, the authors of Vecchiotti et al. presented agronomic studies on the use of ethylene and chitosan in the cultivation of onions. The manuscript was well prepared, but there are some shortcomings in it for improvement, which I present at the end. I would like to suggest the authors change the title of the article. The current title fits more as a key message for research than the title.  I am giving an example of a potential title: Use of ethylene and chitosan in onion seed production. The authors conducted their field research in one year. I think that such studies should be carried out at least three times over a period of three years. The next issues are: 1) I recommend moving table 1 to a supplement; 2) has the seed germination test been performed in accordance with International Rules for Seed Testing? I recommend the manuscript to be published after minor revision.

Other comments:

Line 82 delete extra g

Line 84 write down the number 2 in words

Line 198 the subsection has not been numbered

Line 199 write down the number 2 in words

Line 239 write down the number 4 in words

Line 278 write down the number 2 in words

Line 284 write down the number 2 in words

Line 383 replace entry ...as also showed by [47] with ...as also showed by Balla et al. [47].

Line 433 replace entry ...as shown in [63] with ...as shown in Hughes et al [63].

 

Figures 2; 3 and 4 - Letters showing the difference between the mean results are better written in lowercase

Author Response

#Reviewer_2: I would like to suggest the authors change the title of the article. The current title fits more as a key message for research than the title.  I am giving an example of a potential title: Use of ethylene and chitosan in onion seed production.

Authors: we thank the reviewer for the suggestion. So far, we believe that the generalist title “Use of ethylene and chitosan in onion seed production.” Would better fit a review rather than a research article. In research article, providing the key message in the title increases the scientific and dissemination interests for the article, as stated in many lessons about the strategies to write a good and interesting ms.

 

#Reviewer_2:The authors conducted their field research in one year. I think that such studies should be carried out at least three times over a period of three years.

Authors: we agree with the reviewer that indeed having many environmental replication increases the chances hove having results under variable conditions. Nonetheless, it is similarly important to publish the results to allow other researcher to take advantage of the previous knowledge. In addition, in the horticulture sector, the variability of conditions is partly overcame by reducing the chances of having nutritional lacks of or biotic stress by the high application of synthetic fertilises and active ingredients, that we declared point by point in the table 1. Lastly, the present experiment was funded by the authors and this reduces the chances of having an additional environmental replication (that indeed could be due in different conditions in further projects, especially if funded)

 

#Reviewer_2:The next issues are: 1) I recommend moving table 1 to a supplement;

Authors: thanks for the suggestion. So far, the table 1 is describing important aspect to replicate the experiment. In particular, as explained in the previous response, in the horticulture sector, the variability of conditions is strongly reduced by adding high amounts of fertilises and active ingredients in other that the results does not depend (or depend the less as possible) by any nutritional biotic stress issues. Thus, we think that the table 1 should be placed in the main text so that the reader have clearly in mind that the nutritional aspects and eventual biotic stresses were taken into account at the time of the experiment. Also, these are important since the chitosan may have an effect on the relieve of fungal pathogen. 

 

#Reviewer_2: 2) has the seed germination test been performed in accordance with International Rules for Seed Testing?

Authors: yes, according to the ISTA 2017 chapters 2 and 5, now added. Thanks for letting us note it.

 

#Reviewer_2: Line 82 delete extra g

Authors: done

 

#Reviewer_2: Line 84 write down the number 2 in words

Authors: done

 

#Reviewer_2: Line 198 the subsection has not been numbered

Authors: added

 

#Reviewer_2: Line 199 write down the number 2 in words

Authors: done

 

#Reviewer_2: Line 239 write down the number 4 in words

Authors: done

 

#Reviewer_2: Line 278 write down the number 2 in words

Authors: done

 

#Reviewer_2: Line 284 write down the number 2 in words

Authors: done

 

#Reviewer_2: Line 383 replace entry ...as also showed by [47] with ...as also showed by Balla et al. [47].

Authors: done in all similar entries

 

#Reviewer_2: Line 433 replace entry ...as shown in [63] with ...as shown in Hughes et al [63].

Authors: done

 

#Reviewer_2: Figures 2; 3 and 4 - Letters showing the difference between the mean results are better written in lowercase

Authors: the letter size and indication of lowercase or uppercase is only a convention. We stated that the letters indicates the differences according to the one test applied, with no multiple test that usually require uppercase and lowercase letters. We thus will avoid changing the letter from upper to lowercase

Round 2

Reviewer 1 Report

The authors have reasonably replied to my comments.

Author Response

Authors: we thank the reviewer again for his/her comments that however are identical to the first review round. Here we answer again to the questions raised. We invite the reviewer to check our answer, that also in the R1 version were given to all of his/her comments.

#Reviewer_1 (1) Less theoretical contribution. This manuscript revealed that the yield depression under high doses of ethylene application mostly occurred through a depression of the flower fertility (measured as number of seeds per inflorescence). However, similar researches have already been reported in application of lower ethylene concentration compared to the present study stimulated yield through an increase of the number of inflorescence per unit area (Singh et al., 1995).

Authors: agree the reviewer for his/her comments. So far, we think the reviewer missed the very most of the scientific evaluation of a topic. In particular, the reviewer is citing only one paper (Singh et al., 1995) that, according to his/her evaluation, produced similar results, whereas we showed that the results on this topic were variable. We cited Singh et al. (1995) [our citation n. 32, as can be seen in the discussion section] and showed the differences between our study and the elegant study of these author. Many differences occur, in particular the genotype and environmental conditions were definitely different. Also, the scientific consensus on a topic can’t be built on just one or two studies, but many confirmation and studies are available to build suitable systematic review and systematic metanalyses. In addition, we also showed which other studies had different results compared to our study.

#Reviewer_1 In addition, since lower ethylene concentration application has a positive effect on seed yield, why not set a low concentration of ethylene application control?

Authors: we thank the reviewer for this suggestion. Indeed this may be an option for further study. However, as the reviewer may understand, it’s inconvenient to start an experiment in a new, untested area with definitely low applications since this reduces the chances of finding the presence of an effect. In particular, earlier experiments in an areas (such as the one in the present study) apply relatively high concentration (here we used the recommended rate), that these may be lowered in further studies to highlight the crop behaviour.

 

#Reviewer_1 (2) Poor experimental design. Both the effects of ethylene and chitosan application on the seed yield components and germination trend were measured in this study. However, what's the relationship between ethylene and chitosan? Researchers should elaborate more on the reasons why these two types of PGRs were used in this study.

Authors: the relationship between these two treatments were clarified in the introduction. In particular, chitosan can lower the transpiration, whereas ethylene increases it. These contrasting factors are related to both the net primary production of the crop, from the one side, and the ability of the crop to fill the grain, from the other side. This mechanism has been explored in other species. Thanks to the reviewer suggestion, we now pinpointed this mechanism in the introduction. We also included the recent study dealing with the relationship between ethylene and chitosan in tomato (Journal of Plant Physiology 263 (2021) 153461)

 

#Reviewer_1 To sum up, despite enormous data generated, the findings of the manuscript are correlative. The scientific significance revealed by this manuscript did not reach the average level of Horticulturae at this time.

Authors: as we explained above, we disagree that the results are correlative. In particular, there is no other experiment in similar areas and made in similar conditions yielding the same results, also, the similar results from other areas or conditions were obtained through different eco-physiological mechanisms.