The Effect of Selenium Sources and Rates on Cowpea Seed Quality

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please check the attached document.

The statistical analysis procedures can be improved. For example, it is not clear what was analyzed and how and that authors should indicate in the methodology section the analysis that were applied and how the p-values were generated.

Comments for author File: Comments.pdf

Author Response

Muito obrigado por reservar um tempo para revisar este manuscrito. Por favor, encontre as respostas detalhadas abaixo e as revisões/correções correspondentes destacadas/em alterações de rastreamento nos arquivos reenviados . 

O título foi alterado para “O efeito das fontes e doses de selênio na qualidade das sementes de feijão-caupi”. 

Atributos de qualidade da semente foram incluídos nas palavras-chave.

Em relação à análise estatística, o ponto 2.6 foi melhorado para incluir informações sobre os fatores analisados ​​(7 doses de Se X 2 fontes de Se) e informações sobre o teste de Tukey para obter valores de p e, seguindo a sugestão, os números foram ampliados para maior clareza. 

Reviewer 2 Report

Comments and Suggestions for Authors

Introduction

- line 50-64: information about selenium toxicity is mentioned. However, it is general. It should be mentioned in exact form. In which level is limit for plant toxicity. Or in which level is toxicity for human body?

Methods

- line 69-76: there is necessary to mention exact information about temperature and rainfalls during experiment period for experimental year, not generally according to long-term climate normal.

- line 88-92: add distance among rows

- line 148-163: add methodics used for analyses (who´s methodics were used)

- missing information about used cultivar and its characteristics

- in many studies, effect of climate and growing year was statistically significant in connection to quantitative and qualitative parameters of crops if selenium application was tested. From this reason, one year of FIELD experiment is insufficient. In second year of study, results could be significantly different in different climate. It is strange for me that experiment was done in 2016 and there was much time to repeat it.

Results and discussion

- line 283-307: In discussion, you are writting about importance of Se form and its connection  to Se absorption and its level in crops. Missing information about Se content in seeds – significant factor to physiological seed parameters (first part of discussion is irrelevant because you do not test it in your study). In this connection, thus results are not applicable and comparable for future/other studies.

- line 308-312: missing connection to your results

- line 334-340: just hypothesis without connection tou results of your study. You do not determine polyphenols in cowpea

- line 345-362: very general meaning without exactly described connection to your study

Conclusion

- very short without information about using of results in practice, e.g. for who, it is usable? It is not possible to state it exactly if results was just from one year of field experiment. It does not include reaction of plants to Se application in different climate, e.g. higher/lower rainfalls, different temperature etc. There is evident that different climate results in different yield which influence on the quality/physiological parameters of seeds etc.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. 

In the fourth paragraph of the introduction, the toxicity limit for cowpea and the human body has been inserted.

A graph with exact information on temperature and rainfall during the trial period has been inserted into the text, as suggested. 

Distance among rows is described in item 2.1, fourth paragraph, second and third lines.

We understand that the methods used are well described and referenced where necessary. 

Information on the cultivar used and its characteristics has been inserted in item 2.1, fourth paragraph.

With regard to the experiment carried out in only one year of cultivation, we would like to inform you that we would like to inform you that it was in fact carried out in just one harvest.

Line 308-312: the results were related to the information.

Line 334-340: the information has been taken from the text.

Line 345-362: some terms have been included to improve understanding.

For perspective, we have included a paragraph in the conclusion, as suggested. 

Reviewer 3 Report

Comments and Suggestions for Authors

Title need to revise according to research design, if possible.

introduction must be improved to include need of the project, hypothesis and possible outcomes. 

Line 74, Aw?

Discussion section looks more like an introduction, please discuss your results and compare it with the previous studies. 

how about future perspectives in the conclusion part? 

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. 

The title was changed to “The effect of selenium sources and rates on cowpea seed quality.” 

The need for the project is described in the second paragraph of the introduction: "The use of seeds with good physiological quality is a critical factor in establishing crop cultivation. Seeds with low germination potential and vigor are among the factors influencing low productivity and, consequently, low economic returns. Adequate plant nutrition is also essential for obtaining high-quality seeds. Among the beneficial elements that can be supplied and have the potential to produce a satisfactory response in terms of seed quality is selenium (Se)."

We understand that the possible results are linked to the hypothesis, which is described at the end of the fourth paragraph of the introduction: "It is hypothesized that Se applied via the soil to cowpea crops could improve the physiological quality of the seeds obtained, especially when they are exposed to low and high temperatures during germination."

Line 74 contains Aw. The term is correct because according to the Köppen classification, the region's climate is Aw, tropical humid, with rainy summers and dry winters.

In the Discussion section, we show the metabolic functions of Se and its differences in absorption and effects on plants in relation to its sources, sodium selenate and sodium selenite. We mention some Se studies related to seed quality, but studies in this line of research are really scarce, demonstrating once again the innovation and importance of this work for the world literature. We couldn't find any more scientific papers to include in the discussion, but we believe that our discussion is well presented and well founded.

For perspective, we have included a paragraph in the conclusion, as suggested. 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Recommendations regarding introduction and methods were accepted. On the other hand, I am still convinced that one-year results from field experiment are not sufficient for relevant conclusions (also in combination with using just one cultivar – genotype effect is very signficant for Se application and its impact according my experiences with selenization of many vegetables). From this reason, there is not possible to state exact conclusions, just expectations. Results something indicate but there were not confirmed in second year with different climate. This fact should be surely accepted in formation of conclusions and recommendations influencing from your study. (maybe some expectations etc.)

I have still problem with accepting of discussion level in paper, concretely:

- You do not determine Se content in cowpea seeds. It is a pity because it should be great benefit for paper. In lines 290-308, there are information about Se application and its importance for plant. But it is not confirmed by your results which would be „bridge“ for these findings. In dicusssion, you use turnip (very different species for discussion) and lentil (it is fine). I know that in these area, more experiment with leguminous crops were done. Please, if you have not analysed Se content in cowpea, fill discusssion in the way that you use more studies with crops related to cowpea (seeds as consumable part) and then create „bridge“ (expectation) to your study effect.

 

Final evaluation

- dicussion – needed revision

- conclusions – extremely short and should be revised. In my opinion, conclusions should be done in more precise way, thus with:

a) clear recommendation for future research – how your results helps to develop next research, your expectations and challenges for it

b) expected effects for cowpea plants and growers/processing companies/consumers – how it can be useful in practice

 

Recommendation to future research

- realise more experimental years than just one

- use more cultivars - it is one of the most factor influencing for yield and quality of crops and finally to application of selenium or all substances and its effect to quality

Author Response

We appreciate the observations, all crucial to improve the quality of our manuscript.
The alterations made in the manuscript, and other relevant sentences regarding the reviewers’ observations are highlighted. 
The discussion was improved following the points mentioned, as could be observed in lines 326-366. Legume plants were added to the discussion, explaining Se effect on metabolites in seeds that could improve seed germination and help to explain why Se enhanced seed quality as observed in the present manuscript. All comments are answered within the comment itself under ‘Authors’.
Discussion was also improved, however, we already established the best application rate and source (lines 379-383).  The practical consequences of cowpea application were better elucidated in lines 386-388, from our perspective, the most practical effect of Se application is seedling starting development.
Future perspectives were included in lines 390-394, we believe we should not mention too much the use of another genotypes or the effect of Se over the years in cowpea seeds. This was not the focus of our work and would lead to a more speculative than scientific approach. Thus, mentions regarding these topics were very subtle.