Effect of Row Spacing and Plant Density on Silage Maize Growth, Dry Matter Distribution and Yield

Round 1

Reviewer 1 Report (Previous Reviewer 1)

• Now, I have one question about the significance of lowercase letters, whether "a" is at the maximum or the minimum

  . I refer you to the most recent article published in agronomy.

1.      It is two factor experiment. Why the part of 3.1 and 3.2 are only the two row spacings at plant density 92,000 plants result during growing seasons 2011–2014. The significance marker is different years? That is not correct.

2.      The six terms (T, see dates in Table 2) table 3. There was no relevant data about PH, PW, DMC, LR, SR, ER in Table 2. How to get the RS × T in table 3. It is not clearly.

3.      Fertilizers were applied before seeding. There was not applied fertilizers from 2005-2014?

4.      What was plant density about the datas in different term and row spacing in Table 5.? It was not clear. All the tables have same problem. There were no significantly different at different row spacing in same term within each column. What represent about row spacing datas? It should be explained clearly.

5.      The PH, PW, DMC, ER were lower in 2013 and 2014, why? It should be explained in discussion.

6.      Suggestion modify the all Individual plant characteristics to group plant characteristics.

 

7.      What was practical significance about the research, there was not be explained clearly in abstract or introduction.

Author Response

Response letter is attached.

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 3)

The manuscript has significantly improved and can be worthy to publish. However, suggesting a minor revision to include the limitations of this study at end of the discussion section.

Reviewer 3 Report (Previous Reviewer 4)

Dear Authors

Thank you for considering the comments and suggestions in my review and for answering my questions. 

 

Author Response

Response letter is attached.

Author Response File: Author Response.pdf

Reviewer 4 Report (Previous Reviewer 2)

The authors have substantially improved the manuscript entitled “Effect of Row Spacing and Plant Density on Silage Maize Growth, Dry Matter Distribution and Yield (Agronomy-2343721)”, but still some points need more clarification for the better understandability of the readers of “Agronomy”. Add 1 or 2 specific conclusions with respect to the work presented in the body along with the future prospects. There are still some methodological issues that are not so clear, which can confuse the interpretation of the results and conclusions. The authors did not provide satisfactory explanation of the point raised previously regarding the results section, i.e., “Explain the significant results with percentage increase or decrease values for all the studied parameters?”.  Please pay attention, the authors have revised the conclusion, but it has been found after the comparison of the current version with the previous one that the authors have merely rearranged the statements. In addition, the application of this work is not clearly written. What did the authors want to achieve at the end of this experiment? should be written clearly. Thanks !

Author Response

Response letter is attached.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 1)

Accept in present form

Reviewer 4 Report (Previous Reviewer 2)

Article can be accepted in the present form

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

General

The article presents the results of a field experiment, in which the effect of spatial arrangement and plant density on dry mater distribution in Silage Maize. The authors found that the narrow rows of maize growth in the three years achieved the higher dry matter yield (4.6–10.8%), the author explains that was related to significantly lower losses in plant numbers compared to conventional rows. In addition, the authors found that Neither row spacing nor plant density affected the morphological parameters of maize plants at harvest time. The general feeling is that the manuscript is very ordinary, only plant height and distribution of dry matter in different organs were discussed. And there were significant errors in the labeling of the significance of the differences. Specific comments will follow below.

Title: The title is too broad, “Development and Productivity”, only plant height and distribution of dry matter in different organs were discussed in the manuscript, the research content doesn't support the title. In addition, the study deals with density, whether to consider adding density to the title.

Abstract: 

Abstract is too simple, it's better to rewrite. What is the final conclusion of your research? Narrow rows increased the dry matter yield of silage maize, why? Whether density has any effect on dry matter yield. The aim of this study was to investigate the effect of row spacing on maize plant part proportion growing at harvest time, whether the paper solves this problem is not reflected in the abstract. The abstract is not a copy of the conclusion.

Introduction: 

L52-53, Add literature citations.

L77-78, insufficiently rigorous, “European conditions”, Does it apply to all of Europe?

Materials and Methods:  

L113, Deletion “see”.

L130, 2.4. Statistical analysis, delete the irrelevant part, such as “Table x”,.

Results: 

In the first paragraph of the results, L149-152, “Significantly lower 149 sums of precipitation during the vegetation period were found in 2011 and 2012 (329 mm and 296 mm, respectively) compared to the 2013 and 2014 (488 mm and 408 mm, respectively).” but the DMC on the contrary, how to explain?

There were significant errors in the labeling of the significance of the differences in tables, please check it carefully. If there are errors in the statistical analysis, then I don't think your results make any sense.

There is no explanation of abbreviations in the tables.

Discussion: 

L237-239, “higher temperatures and lower sums of precipitation in May were observed”, higher temperatures and lower sums of precipitation instead more dry matter was produced compared to 2013 and 2014. Despite your explanation that “higher temperatures at the beginning of the vegetation period could be more important than the sum of precipitation in Central Europe”, I am doubtful about that, of course, you can supplement the relevant literature.

L330-332, “For higher plant density, surprisingly enhanced ear ratio in narrow rows could probably be connected with lower plant height in this treatment.” But in your manuscript, plant density and row spacing had no significantly effect on plant height.

Conclusion: Different experimental factors lead to the difference in results. Climatic conditions are not experimental factors and should not be included in the conclusion.

Author Response

Dear reviewer,

the response letter is attached.

Author Response File: Author Response.docx

Reviewer 2 Report

The study entitled ‘Effect of Spatial Arrangement on Development and Productivity of Silage Maize’ is well written and falls within the aim and scope of the Journal. The manuscript can be considered after addressing the following points;

·         Please explain, Why this study is conducted?? Importance of the current study is lacking.

·         Quantitative results should be provided in the abstract. Moreover, future implications can be provided at the end of abstract section.

·         Its worth to add images/photos of experimental sites.

·         How many biological and technical replicates have you used?

·         Did the authors analyse post experimental soil properties?

·         The authors haven’t presented pre- and post- experimental N, P, K contents of studied soil. Did the authors observe any impact of nutrients and corresponding treatments on maize crop growth during study period? 

·         Explain the significant results with percentage increase or decrease values for all the studied parameters?

·         The authors did not provide a clear and coherent argument in the discussion section, can be improved.

·         The conclusion should be concise and to the points indicating the application of the work. Add a solid future prospect statement and link it with the conclusion please.

·         Please check again, the references can be arranged as per journal’s format.

Author Response

Dear reviewer,

the response letter is attached.

Author Response File: Author Response.docx

Reviewer 3 Report

Even though the paper has a new idea to attract readers, the contents of the work has limited satisfaction due to lack of diversity in the research objectives and methodologies. This is quite significant that they have tested in four different years and presented some agronomic traits related to biomass. However, one of the major purposes of cultivating the silage maize is to provide sufficient nutritional support for livestock. The outcomes of the trails should include the results on variation in nutritional contents in biomass that are used for feed, like, protein, ash, fibers (different kinds) and relative feed value. Otherwise, the research seems to incomplete to attain the ultimate goals of this type of maize cultivation. If the authors can include the results of major nutritional measurement of feed traits and then can resubmit it along with improvement in all section accordingly Thus, the paper quality will improve and be worthy for the readers.

Author Response

Dear reviewer,

the response letter is attached.

Author Response File: Author Response.docx

Reviewer 4 Report

Dear Authors

The work submitted for review represents a typical field study of several years. Literature review and research methodology described correctly. Basic statistical analysis (ANOVA) was performed.Results are presented clearly and conclusions are not questionable.

In terms of editing, the work is prepared correctly and requires a few corrections (Manuscript attached).

However, I have two questions:

1) What is the reason for publishing these results so late, there are already new new varieties with shorter FAO?

2) Why is only one cultivar of maize included?

 

The aim of this study was to investigate the effect of row spacing on silage maize growth over the season and on yield and maize plant part proportion growing at harvest time in the Central Europe region over a four-year period. These results could help to better understand the benefits of various row spacing effects in European conditions. The work is therefore important. My question, however, is why are the results published after ten years?  

The subject of seeding density and plant spacing is of fundamental importance, as it affects cultivation technology, yields, plant diseases, production costs, etc.  

Field experiments were evaluated with conventional rows (0.70 m) at a density of 92,000 plants per ha, and narrow rows (0.35 m) at a density of 110,000 plants per ha. That is, a typical single-factor study. Other factors could have been included here: variety, fertilisation, etc.

Other varieties with a different FAO should have been included without consideration

The conclusions are in line with the research findings. 

 

The references are appropriate. Only the fact that the literature items to which the authors refer their findings are more recent than their research is questionable.

Tables and figures are clear - I have no comments. 

 

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

the response letter is attached.

Author Response File: Author Response.docx

Reviewer 5 Report

The topic of the article is relevant. Despite the arrangement of plants in maize being extensively studied in several countries, the regional peculiarities and the use for silage are important peculiar conditions for the generation of information and practical indications. Addresses the effect of reducing row spacing, with some variation in seeding density. It was held for four years in the Czech Republic.

Overall, the article is well written. The summary includes the necessary items, but can be adjusted according to the suggestions made. Keywords must be complemented, including the scientific name of maize.

The introduction addresses the most important aspects, but could be complemented with plant characteristics (architecture and cycle, for example) that can affect arrangement results.

The material and methods lacked some important details that need to be complemented. It is not clear in the material and methods how the control of the plant population was carried out in the trials that did not vary the plant density. Was an adjustment made to the population at the beginning of growth? What motivated differences in the population between row spacings as described by the authors? This is an issue that influences several evaluated characteristics and the interpretation of results. It needs to be better described how the samplings were carried out for evaluations of growth and dry matter yield. The authors cite the size of the plot and the area collected for dry matter yield (two or four central lines of the plots according to the row spacing). Also, four plants were collected randomly during several times to evaluate plant characteristics. How was this accomplished? For example, with a spacing of 0.70 m, the plots were formed by four rows of 5 m. If the two central lines were collected to evaluate the dry matter yield at the end of the cycle, where were the plant samples collected during the cycle? Were they collected from the edge lines? Were they collected from the usable area harvested for yield? If one of these forms was used, we have a methodological problem, as the edges do not faithfully represent the treatments and if they were removed from the useful area, they compromised the plant population, especially in the widest spacing (0.70 m) which had the lowest number of rows. This needs to be clarified and impacts assessed. The ideal is to make a plot with sufficient dimensions to carry out sampling and to reserve a useful area with preserved edges to evaluate the dry matter at the end of the cycle. Another suggestion is to collect the plants in the samples taken during the cycle in sequence on the line with measurement of the harvested area. This would allow transforming some characteristics into values per m² or ha, it would better represent the existing variability among the plants and would avoid choosing, even if unintentionally, the best plants in the plot. Present the coefficient of variation of the tests.

The results are well described, but need adjustments to be consistent. Some results do not match the statistics and others may have the statistics interpreted in another way to support the conclusions. An important issue refers to the effect of spacing on total dry matter at the end of the cycle (harvest). Three years show the effect of narrow spacing in increasing this variable and one year does not. The authors address this issue in the description of the results, indicating that there was no spacing effect on the four-year average. However, they approach this difference in the discussions, trying to explain the different effects in the period 2011-2013 and 2014 and also in the conclusions where they indicate the difference in favor of narrow spacing. It is suggested to review this issue and modify the wording in all items that address this result. In principle, looking at Figure 2, I understand that there was an interaction between spacing and year, but this was not confirmed by statistics using a probability of 5%. Thus, the authors were limited in their approach to spacing. When working in evaluating technologies that do not involve an increase in costs, as in the present case where the variation in row spacing is being evaluated (only requiring adjustment of the sowing equipment), a less restrictive probability could be used, such as 10%. Thus, statistics would support the approach to spacing and year interaction. If the authors' understanding, knowing the reality where the information would be applied, really points to variations in spacing without increasing costs, this change in interpretation could be used. However, this does not rule out the need for improvements in the justification for changing behavior according to the year. The authors try to justify this change as a function of temperature and precipitation, but this is done superficially and does not address specific issues involving the change in row spacing. For example, no water balance is shown to prove the level of water deficit observed in 2014. Also, there is no discussion of why narrow spacing would have lower performance in a year of water stress.

In addition, some methodological issues that are not so clear can confuse the interpretation of results and conclusions. For example, it is described that there was variation in the final population, even in trials that did not use variation in density as treatments. What is the reason for this variation? The trials were sown manually and I believe with uniformity in the management used. However, the authors discuss variations in plant characteristics (such as individual plant weight) in the two spacing, informing that there was a difference in population. If this population difference occurred between the two row spacings, it is expected that smaller/less heavy plants would be found in larger populations as an effect of greater plant competition. As this occurred in narrow spacing, this cannot be mistaken primarily as a spacing effect, but as a population effect. To solve this problem, the unit per area is used. In the present case, this variation in the population seems not to have been controlled and may be confounding the results. It is suggested to review this issue with the necessary adjustments, if possible, so that the row spacing effects are really separated.

The discussion could be deepened, as it presents some justifications for the results, but without fully elucidating what happened in 2014.

Conclusions need to be adjusted for changes in interpretation and statistical support.

The references are mostly current and relevant.

Tables and figures need some adjustments.

Some adjustments are suggested to qualify the paper:

- Lines 2 and 9: it is suggested to use the correct term and standardize it throughout the article. In this case, it would be more appropriate to speak of growth rather than development, as they are different things.

- Lines 8, 13, 15, for example: avoid using the term “determine”, because what determines are the treatments, environment and genetics. Researchers evaluate, quantify, measure.

- Line 19: specify what the yield refers to. Is it grain? Of dry matter? Include the scientific name of maize.

- Line 21: the introduction (and also the discussion) failed to address plant architecture and interaction with plant arrangement. Plant height, type and architecture of leaves, among others. Is the type of plant for grain and silage production the same? What can these differences affect the result in relation to the arrangement?

- Lines 96 and 97: why choose two of the four spacing treatments for evaluation at work? What were the others?

- Line 101: describe the characteristics of the hybrid used.

- Lines 108-109: It is important to present the variability in rainfall distribution and water balance to support the discussion on water deficiency at specific times of the cycle and impacts on results.

- Lines 116-117: describe better how the plants were collected for evaluations. Were they removed from the useful area of the plot? From the edges? Did it reduced the final population?

- Lines 127-128: For the evaluation of the harvested plant ratio (HPR, %) were the plants counted at the beginning and end of the cycle or did the target population (92,000 plants ha^-1) be considered as the initial standard?

- Lines 168-169: check the letters that indicate comparisons between treatments in the tables. Some are in alphabetical order from lowest to highest value. Others are in reverse and others have no defined pattern. This needs to be standardized so as not to confuse the reader.

- Lines 194-195: explain the reason for the difference in plant population (loss of plants) in row spacing treatments.

- Lines 254-256: reports differences in plant height between treatments, but that this was not significant and data are not shown. Avoid making statements not supported by statistics and even more so without showing the data. This may confuse the reader's interpretation.

- Lines 264-265: indicate the complete unit. Is it g plant^-1 or g m^-2?

- Line 289-320: verify that the discussion on characteristics of individual plants and the result of total dry matter are not confused by plant population variation between spacing.

- Line 350: adjust the conclusion according to the suggestions made in the rest of the article. Do not show differences not supported by statistics or modify and report the statistical interpretation to support the conclusions. Only point to water deficiency as a justification if the water balance is presented supporting this statement and the question of variation in the population between spacing is discarded as a factor that may have contributed to the results obtained.

Author Response

Dear reviewer,

the response letter is attached.

Author Response File: Author Response.docx