Response of Barley Genotypes to Weed Interference in Australia
Round 1
Reviewer 1 Report
Comments to Authors
Introduction
1st paragraph, page 2,
Reference for annual cost of weeds to grain growers? Last sentence requires clarification.
2nd paragraph, page 2
Is it only no-till farming that has caused the development of herbicide resistance? Continued use of a herbicide in conventional establishments methods has also led to herbicide resistance (e.g. glyphosate resistant ryegrass).
6th paragraph, page 2
It would be useful to mention the other major weeds of barley in Australia, before focussing on wild oat. Reference for wild oat losses? Need to explain ‘fops/dims’
Materials and Methods
1st paragraph, page 2
What had been grown in the field prior to Winter 2017?
2nd paragraph, page 3
What is ‘high leaf’? How were the seeding rates adjusted based on germination test? Table 1. Define ‘droopy’. You have two very different establishment methods for the oat ‘weeds’. Were the broadcast seeds (Year 1) then covered at all? How close to the target population (125 plants/m2) did you get each year? What was your reason for choosing that population? How does it compare with wild oat populations in Australian barley crops?
Results
Paragraph 1, page 4
For statistical analysis you state that weed infestation levels were a fixed effect, but you provide no data to show weeds/m2 in either year. Table 2. The method states yield was converted to kg/ha, but in Table 2 it is Mg/ha. Should ‘Table 3” in the text be ‘Table 2’? If not Table 3 is missing. If so, change the remaining table numbers.
3.1, Paragraph 1
According to Fig 1a, weed biomass was not lowest in Commander; should be Westminster. Can you use the terms ‘highest’ and ‘lowest’ when difference from other genotypes are not significant? I think not.
Page 6, Figure 3
I can’t find Figure 3 referred to in the text
3.3, 1st paragraph.
Same comment for ‘highest’ and ‘lowest’ in reference to Table 4.
3.4, 1st paragraph
And again, the same comment. These results all need to be rewritten, deleting the ‘highest’ and ‘lowest’ sections. If two results don’t differ significantly, one can’t be ‘higher’ or ‘lower’ than the other.
3.5, first paragraph
What does ‘stand with weeds’ mean?
Discussion
1st paragraph, page 10
Word ‘high’ missing between ‘both’ and ‘WSA’ in the first line?
General
This trial used oat to mimic wild oat as a weed. I have no problem with that. However the ‘weed’ used is another cereal. The text, by implication, used the terms ‘weed’ and ‘weed control’, suggesting that the results are applicable to any weed likely found in a barley crop if herbicides are not applied. In my opinion, you should make it clear that these results are applicable only to wild oat, and add to your discussion some points about what the likely impact of barley genotype may be on other weed species.
Abstract
3rd / 4th line – sentence grammatically incorrect. 5th line – include ‘weed’ before ‘suppressive’. 9th and 10th lines – there are the ‘lowest’ and ‘highest’ words again.
Author Response
Please see attachment.
Comments to Authors
Introduction
1st paragraph, page 2,
Reference for annual cost of weeds to grain growers? Last sentence requires clarification.
Required information has been added.
2nd paragraph, page 2
Is it only no-till farming that has caused the development of herbicide resistance? Continued use of a herbicide in conventional establishments methods has also led to herbicide resistance (e.g. glyphosate resistant ryegrass).
The suggested line has been added.
6th paragraph, page 2
It would be useful to mention the other major weeds of barley in Australia, before focussing on wild oat. Reference for wild oat losses? Need to explain ‘fops/dims’
Major weeds of barley have been mentioned. A reference for wild oat losses has been incorporated. Full name of fops/dims has been provided.
Materials and Methods
1st paragraph, page 2
What had been grown in the field prior to Winter 2017?
The required information has been added in the manuscript. The field was wheat-fallow.
2nd paragraph, page 3
What is ‘high leaf’? How were the seeding rates adjusted based on germination test? Table 1. Define ‘droopy’. You have two very different establishment methods for the oat ‘weeds’. Were the broadcast seeds (Year 1) then covered at all? How close to the target population (125 plants/m2) did you get each year? What was your reason for choosing that population? How does it compare with wild oat populations in Australian barley crops?
The sentence has been corrected. The seed rate was adjusted with 100% germination. Suppose, if seed germination was 80%, then 20% more seeds were added to make it 100%. The same procedure was followed for each genotype to make it 100% germination. As sowing was done with a precision planter, it was near to target population (125 plants/m2) in each year.
Droopy means hanging down limpl (spreading type; not erect). Yes, oat seeds were broadcasted before planting the crop. So these were covered with soil during crop planting operation. We selected oats due to mimic weed and because of having fixed population in each plot.
Results
Paragraph 1, page 4
Table 2. The method states yield was converted to kg/ha, but in Table 2 it is Mg/ha. Should ‘Table 3” in the text be ‘Table 2’? If not Table 3 is missing. If so, change the remaining table numbers.
Unit has been corrected. Table numbers are correct there. There are two ANOVA tables separately. Table 3 is ANOVA for weeds. Table 2 is ANOVA for plant height, panicles and yield.
3.1, Paragraph 1
According to Fig 1a, weed biomass was not lowest in Commander; should be Westminster. Can you use the terms ‘highest’ and ‘lowest’ when difference from other genotypes are not significant? I think not.
The required information has been corrected in the text.
Page 6, Figure 3
I can’t find Figure 3 referred to in the text
The information has been added.
3.3, 1st paragraph.
Same comment for ‘highest’ and ‘lowest’ in reference to Table 4.
Corrected.
3.4, 1st paragraph
And again, the same comment. These results all need to be rewritten, deleting the ‘highest’ and ‘lowest’ sections. If two results don’t differ significantly, one can’t be ‘higher’ or ‘lower’ than the other.
Corrected
3.5, first paragraph
What does ‘stand with weeds’ mean?
Modified the word with tolerance.
Discussion
1st paragraph, page 10
Word ‘high’ missing between ‘both’ and ‘WSA’ in the first line?
Added
General
This trial used oat to mimic wild oat as a weed. I have no problem with that. However the ‘weed’ used is another cereal. The text, by implication, used the terms ‘weed’ and ‘weed control’, suggesting that the results are applicable to any weed likely found in a barley crop if herbicides are not applied. In my opinion, you should make it clear that these results are applicable only to wild oat, and add to your discussion some points about what the likely impact of barley genotype may be on other weed species.
The required information has been added.
Abstract
3rd / 4th line – sentence grammatically incorrect. 5th line – include ‘weed’ before ‘suppressive’. 9thand 10th lines – there are the ‘lowest’ and ‘highest’ words again.
The said sentences have been corrected.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear Editor,
I have reviewed the manuscript entitled “Weed-Competitive Ability of Barley Genotypes in Australia.”
The manuscript has scientific merit; however, it is not suitable to be published on Agronomy. Below I justify my decision:
The method for competitive ability has fatal mistakes that, on my understanding, do not allow the acceptance of the present manuscript in the present form. The correct method to perform this type of experiment is, first of all, an additive series to know in which plant-density the variables will be constant independently of the weed density. Ex. 1, 2, 4, 8, 16, 32, 64, and 128 plants per area. After that experiment, a replacement-series experiment should be performed. Ex. Different proportions of each species, in this case, barley and oat: genotypes maintained under monoculture or associated in a mixture using different proportions, as follows: 100:0 (barley monoculture), 75:25, 50:50, 25:75, and 0:100 (oat monoculture).
Detailed literature can be found in Radosevich RS, Holt JS, Ghersa C. Ecology of weeds and invasive plants: relationship to agriculture and natural resource management. New Jersey: Wiley-Interscience; 2007.
In general, the manuscript is well written and present valuable results to the farmers. This type of study may represent a local recommendation on barley cultivation, but not competitive ability because of some methodological issues. I would suggest that the authors change the focus from “competitive ability” to weed interference. After that and addressing all points I highlighted below, the manuscript can be considered for publication.
I am not willing to recommend the publication of the present manuscript as “competitive ability,” but so, if the subject will be changed to weed interference in genotypes of barley.
Abstract
If the authors used numbered lines, that would be very useful.
I would suggest describing how many genotypes were used and also the methods used in the trials.
Introduction
The second paragraph: please cite a source of information. “AU$ 3.3 billion”.
Fifth paragraph: I don’t think that “genotypes having WSA provide WEED CONTROL…” I would suggest to the authors to find a more appropriate word to replace “control” in this case.
Seventh paragraph: please cite a source after “AU$ 28.1 million”. Please rewrite this sentence “Its resistance to fops/dims herbicides were reported during a survey conducted in 2005 in Western Australia”.
Material and Methods
“Barley genotypes were selected on the basis of vigour index determined in previous field experiments that measured high leaf and ground cover at seedling and early tillering growth stages.” It would be great whether the authors have a reference to that study.
Is the Seeding rates (125 plants m-2) of each genotype a recommended density for all of the studied genotypes? In general, each genotype has a different density recommendation. Please clarify to the readers.
How did the oat was sown? Was it using the machine, manually, randomly, in-between the crop row? Please explain that to the readers. If it was sowed in between rows, it is an issue. The weed-interference in a crop is different if according to the weed position, as well as the suppressive ability of the crop-plant. I looked at Figure 3 and it seems that the weeds were sown in between crop-rows; however, the low quality of the photo did not allow me to see that in detail. Please make sure to describe these points as well as adding a high-quality pic.
Table 1. Are those genotypes commercialized? If so, I would ask the authors to add the importance of each in the market - I mean, how many % of the market each genotype does represent.
Barley genotypes were sown at a depth of 5 cm. This sentence is not in the correct place. Please move that to a more proper context.
Please clarify the following sentence: “Nitrogen (N) at 92 kg ha-1, in the form of urea, was applied as a basal dose in the crop.” It is not clear how or when it was performed.
Please describe what correlation method was used.
I would ask the authors to add a figure containing the environmental conditions during the experiments.
Results
Table 2: what does the “WIL” mean? Please describe the means of all abbreviations on the bottom of the table.
Figure 1: I would recommend to the authors to add letters to show differences among genotypes. It will be the most straightforward way for the readers to see the differences.
I did not see how “Panicles Per Meter Row Length” data was collected on MM. Please describe that.
I would suggest changing the “The number of panicles was influenced by the interaction effect of genotype and weed competition level” to “The number of panicles was influenced by the interaction effect of genotype and weed interference level.” As the field was irrigated and we do not know the environmental conditions during the field experiments, as well as the N, was supplemented, the authors can not say that “competition” happened; if so, please describe what the limiting factor is. Whether the limiting factor is unknown, please adjust the term to “weed interference.” I also would like to ask the authors to change that terminology in the whole document.
Discussion
The discussion is a little repetitive with the Results section. It does need an extensive improvement to make it clear the message of the present manuscript. Please reread it carefully and discuss it without the need to repeat the results.
Conclusions
What do the authors recommend after these studies?
Did the questions proposed by the authors were answered? Please improve that and make that clear.
Author Response
Please see the attachment.
The method for competitive ability has fatal mistakes that, on my understanding, do not allow the acceptance of the present manuscript in the present form. The correct method to perform this type of experiment is, first of all, an additive series to know in which plant-density the variables will be constant independently of the weed density. Ex. 1, 2, 4, 8, 16, 32, 64, and 128 plants per area. After that experiment, a replacement-series experiment should be performed. Ex. Different proportions of each species, in this case, barley and oat: genotypes maintained under monoculture or associated in a mixture using different proportions, as follows: 100:0 (barley monoculture), 75:25, 50:50, 25:75, and 0:100 (oat monoculture).
Detailed literature can be found in Radosevich RS, Holt JS, Ghersa C. Ecology of weeds and invasive plants: relationship to agriculture and natural resource management. New Jersey: Wiley-Interscience; 2007.
In general, the manuscript is well written and present valuable results to the farmers. This type of study may represent a local recommendation on barley cultivation, but not competitive ability because of some methodological issues. I would suggest that the authors change the focus from “competitive ability” to weed interference. After that and addressing all points I highlighted below, the manuscript can be considered for publication.
I am not willing to recommend the publication of the present manuscript as “competitive ability,” but so, if the subject will be changed to weed interference in genotypes of barley.
Agreed. We have changed the title to weed interference.
Abstract
If the authors used numbered lines, that would be very useful.
It was there, but during submission has been deleted automatically.
I would suggest describing how many genotypes were used and also the methods used in the trials.
Information was already there (eight genotypes and the design was split plot), page -5.
Introduction
The second paragraph: please cite a source of information. “AU$ 3.3 billion”.
Added
Fifth paragraph: I don’t think that “genotypes having WSA provide WEED CONTROL…” I would suggest to the authors to find a more appropriate word to replace “control” in this case.
Corrected with “reducing weed seed bank”.
Seventh paragraph: please cite a source after “AU$ 28.1 million”. Please rewrite this sentence “Its resistance to fops/dims herbicides were reported during a survey conducted in 2005 in Western Australia”.
Added and the said line has been modified.
Material and Methods
“Barley genotypes were selected on the basis of vigour index determined in previous field experiments that measured high leaf and ground cover at seedling and early tillering growth stages.” It would be great whether the authors have a reference to that study.
These are unpublished data and we have mentioned now.
Is the Seeding rates (125 plants m-2) of each genotype a recommended density for all of the studied genotypes? In general, each genotype has a different density recommendation. Please clarify to the readers.
No, in Australia, it is 125 plants/m2 for all commercial lines. As planting is done with a precision planter; therefore, recommendation is based on plants/m2, not on kg/ha.
How did the oat was sown? Was it using the machine, manually, randomly, in-between the crop row? Please explain that to the readers. If it was sowed in between rows, it is an issue. The weed-interference in a crop is different if according to the weed position, as well as the suppressive ability of the crop-plant. I looked at Figure 3 and it seems that the weeds were sown in between crop-rows; however, the low quality of the photo did not allow me to see that in detail. Please make sure to describe these points as well as adding a high-quality pic.
Information was already there. In the first year, oat seeds were broadcasted. In the second year, oat seeds were drilled to get rid of volunteer oat plants (of previous year). For drilling, we have followed the procedure described by Zerner et al. 2016
Zerner, M. C.; Rebetzke, G. J.; Gill.G. S. Genotypic stability of weed competitive ability for bread wheat (Triticum aestivum) genotypes in multiple environments. Crop Pasture Sci. 2016, 67, 695-702.
Confusion in photo was due to border rows. In between the plots, two rows of oat were also planted to get rid of border effect; as the data were recorded from four crop rows.
Table 1. Are those genotypes commercialized? If so, I would ask the authors to add the importance of each in the market - I mean, how many % of the market each genotype does represent.
Four cultivars are commercial. But we do not have the data of % of the market of each genotype.
Barley genotypes were sown at a depth of 5 cm. This sentence is not in the correct place. Please move that to a more proper context.
Moved
Please clarify the following sentence: “Nitrogen (N) at 92 kg ha-1, in the form of urea, was applied as a basal dose in the crop.” It is not clear how or when it was performed.
Information has been added. “It was applied before planting of the crop using a three point linkage, tractor mounted, fertilizer spreader”.
Please describe what correlation method was used.
Added, it was linear.
I would ask the authors to add a figure containing the environmental conditions during the experiments.
Figure has been added.
Results
Table 2: what does the “WIL” mean? Please describe the means of all abbreviations on the bottom of the table.
Mentioned: Weed infestation level.
Figure 1: I would recommend to the authors to add letters to show differences among genotypes. It will be the most straightforward way for the readers to see the differences.
Added.
I did not see how “Panicles Per Meter Row Length” data was collected on MM. Please describe that.
Information has been added.
I would suggest changing the “The number of panicles was influenced by the interaction effect of genotype and weed competition level” to “The number of panicles was influenced by the interaction effect of genotype and weed interference level.” As the field was irrigated and we do not know the environmental conditions during the field experiments, as well as the N, was supplemented, the authors can not say that “competition” happened; if so, please describe what the limiting factor is. Whether the limiting factor is unknown, please adjust the term to “weed interference.” I also would like to ask the authors to change that terminology in the whole document.
Suggested corrections have been incorporated.
Discussion
The discussion is a little repetitive with the Results section. It does need an extensive improvement to make it clear the message of the present manuscript. Please reread it carefully and discuss it without the need to repeat the results.
Discussion has been improved in the light of both reviewers. Some repetitive lines were removed.
Conclusions
What do the authors recommend after these studies?
Information has been added.
Did the questions proposed by the authors were answered? Please improve that and make that clear.
Yes, we answered all the three questions in conclusions.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
I believe that the authors did a good job, and the manuscript has been improved.
I’ve made some comments to be addressed.
Title: I’m happy with the authors agreed to change the manuscript focus from “ability” to “interference.”
Abstract
Line 16-17: please rewrite from “In this study, the weed interference ability of eight barley genotypes was assessed with a model weed, ‘oat’ plant.” To “In this study, the effects of weed interference on eight barley genotypes were assessed.” I strongly recommend that the authors carefully read the whole manuscript identifying and correcting sentences with “ability.” It must make sense.
When I asked the authors to describe the methods, I meant the two years of field study. This sort of information will help to attract the reader's attention. Readers will assess precise methodological details on the MM section.
“Two years of field experiments were performed in a split-plot design with three replications.” The rest of the phrase “Main plots ….genotypes.” can be deleted.
L19: Since the authors do not know what environmental factor is limiting, please replace “competition” for “interference.” I strongly recommend the authors do the same in the whole manuscript.
Core ideas:
It is well known that more competitive crop genotypes are important weed management practices.
Rank the studied genotype is a good idea. Please rewrite this section.
L 71: the word “weed control” still there. Does WSA control weeds? I would suggest the authors find a more appropriate sentence to replace “weed control.”
L 114-116: I raised a question about de barley’s density, and I am not satisfied with the author’s answer. I think I was not well understood. So, let's try again – my point is that, in general, each genotype/cultivar has its particular density recommendation (plants m-2). I would like to ask the authors to make sure that precisely the same density is the official plant density recommendation for all of the eight studied genotypes. If yes, perfect; if no, the authors must justify.
L 125: doubled dots.
L126: if the authors have an official recommendation for barley management in Australia to present as the reference will be very useful. Thus, if the readers will be interested in to know how it is done in Australia, they can search for more details.
L126: it is not clear if the urea was applied over the soil (broadcast) or into the ground. Please address it.
L 165: please mention briefly how the environmental data was collected, OR the authors can also add that information to the Figure 2 description.
Figure 1: the authors said that they added the letters to differentiate the results among genotypes better. However, in this file, I was not able to see that – I can see only the bar interval; maybe it might be some software compatibility issue. Anyway, please make sure it is added. Also, I would recommend doing the same in Figure 4.
L 329: please replace “weeds” for the “oat – or studied species”.
Conclusions
There are some repetitive words such as “suggest.” Please find the proper words to replace some of them.
Author Response
We again highly appreciate the remarks of reviewer #2 for the improvement of the manuscript. The manuscript has been revised in the light of useful comments. All the comments have been incorporated in the revised version carefully. For clarity, the comments and suggestions will appear in the black colored text; while our response will appear in the blue text. In the manuscript also, specific changes can be seen in the highlighted text. We hope that the revised manuscript is now acceptable in “Agronomy”.
Comments and Suggestions for Authors
I believe that the authors did a good job, and the manuscript has been improved.
Thanks
I’ve made some comments to be addressed.
Title: I’m happy with the authors agreed to change the manuscript focus from “ability” to “interference.”
Abstract
Line 16-17: please rewrite from “In this study, the weed interference ability of eight barley genotypes was assessed with a model weed, ‘oat’ plant.” To “In this study, the effects of weed interference on eight barley genotypes were assessed.” I strongly recommend that the authors carefully read the whole manuscript identifying and correcting sentences with “ability.” It must make sense.
The said sentence has been corrected. The word “ability” has been replaced where required. Some terms like weed tolerance ability, weed suppressive ability are well-defined terms; therefore, we feel not to change that.
When I asked the authors to describe the methods, I meant the two years of field study. This sort of information will help to attract the reader's attention. Readers will assess precise methodological details on the MM section.
“Two years of field experiments were performed in a split-plot design with three replications.” The rest of the phrase “Main plots ….genotypes.” can be deleted.
The said sentence has been corrected.
L19: Since the authors do not know what environmental factor is limiting, please replace “competition” for “interference.” I strongly recommend the authors do the same in the whole manuscript.
The said word has been replaced, where required.
Core ideas:
It is well known that more competitive crop genotypes are important weed management practices.
Rank the studied genotype is a good idea. Please rewrite this section.
Corrections have been made.
L 71: the word “weed control” still there. Does WSA control weeds? I would suggest the authors find a more appropriate sentence to replace “weed control.”
The word has been replaced.
L 114-116: I raised a question about de barley’s density, and I am not satisfied with the author’s answer. I think I was not well understood. So, let's try again – my point is that, in general, each genotype/cultivar has its particular density recommendation (plants m-2). I would like to ask the authors to make sure that precisely the same density is the official plant density recommendation for all of the eight studied genotypes. If yes, perfect; if no, the authors must justify.
We kept a uniform seeding rate for all genotypes. The recommended rate in Australia is 120-150 plants m-2, and we used a uniform seeding rate of 125 plants m-2 for all genotypes.
L 125: doubled dots.
Removed.
L126: if the authors have an official recommendation for barley management in Australia to present as the reference will be very useful. Thus, if the readers will be interested in to know how it is done in Australia, they can search for more details.
The weblink has been provided in the manuscript.
L126: it is not clear if the urea was applied over the soil (broadcast) or into the ground. Please address it.
It was broadcasted/spread with a machine.
L 165: please mention briefly how the environmental data was collected, OR the authors can also add that information to the Figure 2 description.
The information has been provided.
Figure 1: the authors said that they added the letters to differentiate the results among genotypes better. However, in this file, I was not able to see that – I can see only the bar interval; maybe it might be some software compatibility issue. Anyway, please make sure it is added. Also, I would recommend doing the same in Figure 4.
Letters have been provided in Figures. We feel that with LSD value, there is no need for alphabetical letters. Anyhow, we are happy to incorporate it. In general, we feel that alphabetical letters are needed in DMRT design.
L 329: please replace “weeds” for the “oat – or studied species”.
Replaced.
Conclusions
There are some repetitive words such as “suggest.” Please find the proper words to replace some of them.
Many repetitive words have been replaced.
Author Response File: Author Response.pdf
