Grain Yield Potential and Stability of Soybean Genotypes of Different Ages across Diverse Environments in Southern Africa

Round 1

Reviewer 1 Report

This paper is comparing 42 genotypes across several countries and two seasons. A lot of data was generated and the conclusion the main point is that the environment plays an important role and that there is a genotype by environment interaction. This seems like a common observation. This part is not discussed in the discussion section. Why is this research different, what is unique and what is similar to previous research. in Table 1 the description of the cultivars is minimal so we learn that a unknown genotype by the code 28 was the best. Anytime research is done one genotype will be the best. So why was this genotype the best any reason? Did it have disease resistance, late maturing, standing ability, branching etc?? The authors try to make a point that genotypes released more recently would have more environmental tolerance. However G25 was released in 2005 and 13 genotypes were release later.

Although there is a lot of interesting data in the paper I would like to see a bit deeper discussion on what these findings mean in the advancement of science. Line 286 states considering the two analytical method G1 and G25 were the best and thus recommended for cultivation across the three countries. If it is recommended I would imagine that a lot more can be said about these genotypes. However, what can we learn from this paper to advance science? 

Other comments.

In the paper authors use, germplasm, genotype and cultivar.

It is suggested that the authors settle on the terminology genotype throughout the paper. Change all to genotype.

Seeding rate was about 350 000 seeds per ha. The established plants per ha would be closer to 315 000 assuming 10% of the seeds did not make it into a plant. It is not realistic to assume that all seeds planted also established.

When was the crop seeded.  Where there any diseases or pest that could have effected the yield. There is only a statement that crop protection was applied and weeds were controlled.

There was difference in maturity between 120 and 140 days. Were all harvested at the same time. The early maturing should have been mature for some time.

Table 1 does not have much information. The entry number column seems not relevant as it is this information is not use in the paper. Authors use the genotype code. Include the maturity of the genotype.

Order of the table seems a bit odd. It is not ordered by genotype. I looks as it is ordered by release year but G15 and G16 are out of sequence.

Table 3. The latitude and longitude do not make sense. There are only 60 minutes per degree and some number for minutes are more than 60. I prefer a decimal degree indication. I tried the info from the table for Lusaka See below and found a completely other location. Please make all info in decimal degrees and accurate. Include what the rainfall represent (Nov to April or other???) would not be clear for international reader.

Probably table 3 is intended on line 131.

Line 147 G28 was the best.  Better write something like G28 was among the top four ranked genotypes in at least seven……

Table 4 do not capitalize named of environment. Use similar to table 2.

Table 5 has a lot of data. For the mean column it would be good to indicate the LDS 0.05 so see if numbers are actually different in the column.

Not exactly sure that the rank column is needed. The mean column is arranged by yield and the legend states of the top 21 genotypes.

Possibly can include info form table 7 in table 5.

In the legend probably only the abbreviations needed no need to indicate the season as it is already in the top.

Table 6. Not sure how much this information is contributing to the paper. Maybe the IPAC score is important but the same number is presented in the Figure and there is no need to double up.

Figure 1 is not readable. Has good information but needs to be presented differently. Also possibly make two sections for Fig 1. One for Environments and the other for GE

Table 7 has the same numbers as in Table 5. It is not clear to me what the % of the mean is indicating. It is it the mean of all 42 genotypes. Why is this important? I think the cultivar superiority index can be included in table 5

My suggestions and edits are included in a word and pdf file

Comments for author File: Comments.pdf

Author Response

I write, on behalf of my co-authors to sincerely appreciate your insightful comments which significantly improved our manuscript. We have attended to all the comments positively. Thank you.

Reviewer 2 Report

TITLE:
Grain yield potential and stability of soybean germplasm across diverse environments in Southern Africa
AUTHORS:
Hapson Mushoriwa, John Derera, Eastonce T. Gwata*, Isack Mathe, Pangirayi Tongoona
* Correspondence: [email protected]
ABSTRACT:
The abstract is clear (It presents very well the problem), but after a complete reading of the document, however, what is presented in the summary does not match what you concluded in the conclusions.
1. INTRODUCTION:
It’s very good, simple and clear
2. MATERIALS AND METHODS:
 In point 2.1. it would be important to mention more weather conditions such as maximum and minimum temperatures. Because we are aware of the constraints that these two abiotic factors cause on soybeans
 In point 2.2. you will be should mention the name of the active substance of the herbicide and doses of application
 What was the application date? You mention in your document that you did weeding after manual sowing
 I think you could reinforce this chapter a little more and put the temperature data (maximum and minimum) for each location in the tables and explain better the meaning of the treatments (genotypes + environments + interactions) as in line 119 in the results
3. RESULTS:
This chapter is a little confusing, but that meet the expectations and objectives of the program; however, there were some comments:
 The references to the tables are not clear and makes it difficult for the reader to perceive
 Tables should be placed in the text immediately after their reference.
 I do not understand table 4, it seems that it does not correspond to the results presented in lines 130 to 149.
 I think that tables 5, 6 and 7 should be presented before table 3 (ANOVA)
4. DISCUSSION:
References are very well introduced in the text.

Author Response

I write, on behalf of my co-authors to sincerely appreciate your insightful comments which significantly improved our manuscript. We have attended to all the comments positively. Thank you.

Author Response File: Author Response.docx

Reviewer 3 Report

• The work presented for evaluation raises an interesting and important topic. Like the authors, I believe that no laboratory, genetic or molecular tests are able to check the usefulness of a given plant variety in a specific environment so well. Therefore, such field research is as important as molecular research. Appreciating the amount of work of the authors, however, I have some comments as to the correctness of the data compilation.
• The authors cultivated 42 soybean genotypes over two seasons. In the 2010/11 season, soybeans were grown on 5 regions (in 3 countries). In the next season (2011/2012), the seed was grown on the same 5 regions and 3 more. I have doubts whether 3 additional positions in the second season should be included in the data evaluation. These data are a valuable source of data, however, I believe that they should not be included in the research model presented by the authors.
• In my opinion, the authors should describe the analyzed genotypes in more detail.

In the Introduction section, I found two sentences that should be corrected.

Not very good wording. Perhaps it should be improved. I understand what the authors meant, but the overtone of the sentence is illogical

...The crop is exposed to the influence of genotype by environment interaction (GEI) which...

I don't understand how the interaction of the environment with the genotype can cause " limit genetic progress". Please, the authors explain what they meant.

... In addition, GEI can limit genetic progress...

• I think that the work should be subject to linguistic proofreading.
• I have no comments on the description of the results and the method of data presentation. I consider it is done correctly.

In my opinion this manuscript in its current form should not be published in Agronomy. Additionally, I believe that after a major revision, authors may re-add a work to "Agronomy" but as a "short communicate" and not as a "research paper".

Author Response

Dear Editor

I write on behalf of my colleagues and myself to firstly thank you for facilitating the reviewing and publication process of our manuscript. We also sincerely express our gratitude to both reviewers for their constructive and insightful comments that improved our manuscript significantly.

Secondly, we state categorically that we agree with the comments that were made by the reviewers and present the list of our comprehensive responses to all the comments as indicated below.

We await to hear from you before we submit our next manuscript. Many thanks and kind regards

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Grain Yield potential and stability of soybean genotypes……

In general the document has greatly improved. the main thing remaining is that in the document the terms variety (varieties), cultivar(s) and genotypes are used inter changeably. This is confusing because the terms are not defined. the authors decided that the genotype x environment is one of the main aspects of the paper. Great. But please stick to the wording genotypes throughout the paper. CHANGE all if possible or define and use other word than genotype. In this paper it should be genotype superiority index and not cultivar superiority index.

The second major aspect is that by coding the genotypes the value of the paper has greatly decreased. I suggest adding the true genotype indication (name) in table 1. In that way other researchers can utilize this great research. Without actually giving the names of the released genotypes the value of the paper is greatly limited.

Third author no country given after Thohoyandou include South Africa

Please do a search for cultivar(s) in the paper and change ALL to genotypes

Please stick to one description. Authors currently use: genotype (preferred), varieties (line 20) and cultivar (21). 

If you want to introduce the term cultivar or variety please describe what the difference is between genotype and cultivar, between cultivar and variety.

The terms are often used genotypes, varieties, cultivars are often used interchangeably but in this scientific paper please stick to one word to avoid confushion.

Line 23 and cultivar superiority index. The paper is about genotypes so should be genotype superiority index.

Line 23 ….of soybean varieties. Should be soybean genotypes

Line 26 cultivar should be genotype.

Line 51 why use cultivar superiority index. In this paper stick to genotype superiority index.

If you want somewhere in the paper you could write genotype superiority index is also named cultivar superiority index

Line 58 coun-tries should be one word countries

Line 65 uses cultivars (so what is the difference between cultivar and genotype???). For this paper to me it would be better to stick to genotypes. IF authors feel there is a reason to use other words than you will need to explain what you mean by genotype and what you mean by cultivar.

74 again the word cultivar is used. WHAT IS THE DIFFERENCE between genotype and cultivar?

From what I read your “genotypes” were officially released soybean genotypes to be utilized by grower. Many would call that a cultivar.

The reason why I am a stickler on your use of words I that there can be a number of interpretations for instance:

A variety could refers to a variation within a plant species that develops naturally in the environment. Unlike a cultivated plant, a variety does not require human intervention.

A plant cultivar refers to a variation within a plant species that has been developed by a human intervention through controlled plant breeding, as opposed to occurring naturally. The term “cultivar” is a portmanteau of "cultivated variety." 

One definition of genotype is The genotype of an organism is its complete set of genetic material.

In the original paper the term G x E (genotype) was a dominant theme. Therefore if you use genotype please stick to the same word.

In line 85 Authors describe what is meant. Genotypes, which were released in Zimbabwe…  So we know what genotypes are. Use this word throughout.

Line 86. Authors state: for convenience of the study, the genotypes were coded….

I understand the reasoning but it reduces the value of the paper greatly. Table 1 has enough space to actually name the genotype (as they were released there should be an official designation for each genotype. Followed by the code. In additional tables the code can be used as the reader has the key and can find out what the genetics is. Without the true name indicated in the paper the value of the manuscript is greatly reduced.

Line 103 conclude with period.

Line 107 under maturity.    Days after planting

Line 156  Include what the rainfall represent i do not understand over the two seasons  I would understand: “from seeding to harvest “ (Nov-Dec to April or other???) This would make it clear for international readers.

Table 2 Lusaka GPS does not seem to be accurate. Lusaka -15.41 28.29 seems to be in the city not an agricultural field

Line 181 needs super script ha-1 needs to be ha^-1 (twice)

Line 190 change per hectare to ha^-1

Lines 236-238. It would be much better to change all language to genotype and call CSI as GSI

You could add:” the GSI is similar to cultivar superiority index [18] . In this way authors have made the connection with paper 18 but in this manuscript are consistent with using the word genotype.

Line 397

Figure 1 is not readable. Has good information but needs to be presented differently. Also possibly make two sections for Fig 1. One for Environments and the other for GE

Line 456-458 use genotypes instead of cultivars

Line 469 use scientific name for frogeye leaf spot

In section 500-to 517 stick to the established terminology genotype

Line 501 varietal age should be “when genotype was released”

Line 502 and 503 stick to genotypes.

506-507 use genotype

Author Response

We would like to sincerely thank you once again for the constructive comments that improved our manuscript tremendously. 

Author Response File: Author Response.docx