Wide–Narrow Row Planting Pattern Increases Root Lodging Resistance by Adjusting Root Architecture and Root Physiological Activity in Maize (Zea mays L.) in Northeast China
Round 1
Reviewer 1 Report
Manuscript is tremendously improved; results are well presented with bold comments, underlining their importance. Authors have connected previously omitted connection between meteorological factors and obtained results. Conclusion is also improved.
Author Response
Reviewer 1: Manuscript is tremendously improved; results are well presented with bold comments, underlining their importance. Authors have connected previously omitted connection between meteorological factors and obtained results. Conclusion is also improved.
Response: Thank you.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Reviewer’s comments to the article:
Liu et al.: Wide–narrow row planting pattern increases root lodging resistance by adjusting root architecture and root physiological activity in maize (Zea mays L.) in Northeast China
Dear Authors,
the paper submitted is a very interesting and well-written study with significant novelties. I supported the publication of the paper after some minor revisions, considering the following remarks:
1) L28: As “root lodging” and “root lodging resistance” are mentioned frequently, they should be abbreviated here and then used consistently throughout the text.
2) L48: Include the storage of assimilates, as another key function of the root system.
3) L73: I suggest to specify soil type according to FAO-WRB classification system [IUSS Working Group (2015): World Reference Base (WRB) for Soil Resources 2014, update 2015. International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports 106, FAO, Rome]. It is more recent and widely accepted.
4) L74–76: Weather anomalies, mentioned in the Discussion (L330–334), should be replaced here, when climate is described. Demonstrate the long-term average of precipitation and temperature in the Fig. 1 for reference.
5) L81: Indicate the reason for choosing contrasting line direction for planting pattern 1 and 2. It is not obvious.
6) L111: Considering that field soil in the area was “viscous and heavy”, indicate how the loss of fine roots was minimalized during washing. Maybe a root flotation method was applied? RLD is strongly influenced by the amount of fine-root, and thus the root extraction manner. Mesh size of 0.4 mm seems to be adequate, but it retains many soil mineral particles.
7) L128–129: Describe the technique of root preparation before scanning using Winrhizo, e.g. dissection in water-filled tray or other method.
8) L135: More accurate identification of phenology stages is necessary, according to a well-known scale (e.g. BBCH or other).
9) L157 implies the occurrence of natural root lodging. Is it a common phenomenon in a “normal” year without storm event?
10) L187: You mentioned here the Pearson rank correlation, but the analysis was performed by using linear regression analysis. Improve the description of data analysis.
11) L196–196: Explanation for this important results seems to be missing from the discussion. I think it is very necessary.
12) L225–231: Percentage differences between treatments is worth indicating in the text, as they are hardly visible in the figures.
13) Table 1: In my opinion, Table 1 could be replaced by column graph, as was applied to demonstrate the other results. This maybe improve the comparability of the results.
14) L269–274: Which test was applied for analyzing the significance of the regressions (e.g. F test)?
15) Fig 7: Range of axes in the graphs should be adjusted to the range of x and y data in order to improve the visibility. Particularly the vertical axis of the top graph should be improved. Otherwise, extrapolation of the regression lines seems to be unreasonable.
16) L294–295: “Generally, plants with higher RLD have better water and nutrient absorption efficiency, resulting in higher dry matter accumulation and yield.” It is generally true in a limited environment, but not surely under optimal conditions, considering trade-off between above- and belowground plant organs.
17) L305: More references are necessary here.
18) L307: “The root system is responsible for the absorption and translocation of water and nutrients.” Consider to delete the sentence, it belongs to the introduction.
19) L309–311: “Therefore, more and thicker roots can absorb more water and mineral nutrients and synthesize more compounds.” More explanation is needed. Thicker roots have smaller surface area in proportion to the root mass.
20) L321–322: “Maize roots mainly absorb NO3–, part of which is reduced to NH4+ by nitrate reductase and nitrite reductase.” Add a relevant reference to this statement.
21) L329: “A higher potassium concentration can improve lodging resistance”. A brief explanation about the underlying mechanism is needed here.
Author Response
the paper submitted is a very interesting and well-written study with significant novelties. I supported the publication of the paper after some minor revisions, considering the following remarks:
- L28: As “root lodging” and “root lodging resistance” are mentioned frequently, they should be abbreviated here and then used consistently throughout the text.
Response: “root lodging” and “root lodging resistance” were improved “RL” and “RLR”.
- L48: Include the storage of assimilates, as another key function of the root system.
Response: It was improved as ‘some of them are transported from roots to shoots through the xylem sap for the growth and development of shoots and grain yield’.
3) L73: I suggest to specify soil type according to FAO-WRB classification system [IUSS Working Group (2015): World Reference Base (WRB) for Soil Resources 2014, update 2015. International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports 106, FAO, Rome]. It is more recent and widely accepted.
Response: It was improved ‘Phaeozems (FAO-WRB classification system, 2015)’.
4) L74–76: Weather anomalies, mentioned in the Discussion (L330–334), should be replaced here, when climate is described. Demonstrate the long-term average of precipitation and temperature in the Fig. 1 for reference.
Response: Monthly average temperature and precipitation amount of ten-year average were added in Fig. 1.
5) L81: Indicate the reason for choosing contrasting line direction for planting pattern 1 and 2. It is not obvious.
Response: It was added ‘Considering that the ridge direction may affect the growth of maize, we designed east-west and north-south ridge directions’.
6) L111: Considering that field soil in the area was “viscous and heavy”, indicate how the loss of fine roots was minimalized during washing. Maybe a root flotation method was applied? RLD is strongly influenced by the amount of fine-root, and thus the root extraction manner. Mesh size of 0.4 mm seems to be adequate, but it retains many soil mineral particles.
Response: Soil clumps were soaked in water for 12h, detergent was added to the water to help to separate roots form soil particles. Finally, the clods and plant debris are removed.
7) L128–129: Describe the technique of root preparation before scanning using Winrhizo, e.g. dissection in water-filled tray or other method.
Response: It was add ‘While scanning, the root sample was placed in a transparent plexiglass rectangular dish (200 mm × 150 mm) with a layer of water about 5 mm deep to minimize root overlap. When necessary, to fit the rectangular dish, the root was separated into subsamples’.
8) L135: More accurate identification of phenology stages is necessary, according to a well-known scale (e.g. BBCH or other).
Response: It was improved ‘V12, VT and 3 weeks after VT’.
9) L157 implies the occurrence of natural root lodging. Is it a common phenomenon in a “normal” year without storm event?
Response: Root lodging occurs in the absence of extreme weather, its rate was low.
10) L187: You mentioned here the Pearson rank correlation, but the analysis was performed by using linear regression analysis. Improve the description of data analysis.
Response: Pearson rank correlation was improved ‘linear regression analysis’.
11) L196–196: Explanation for this important results seems to be missing from the discussion. I think it is very necessary.
Response: It was increased ‘In the present study, the number of nodal roots of the eighth whorl in 2017 and the diameter of nodal roots of the eighth whorl in 2016 and 2017 were significantly higher than those in pattern 1, this may be related to the different leaf photosynthesis and its assimilate supply to the root due to the different canopy structure between patterns 1 and pattern 2 [20, 21], but it has not been reported in the literatures’.
12) L225–231: Percentage differences between treatments is worth indicating in the text, as they are hardly visible in the figures.
Response: It was increased ‘Compared with pattern 1, the nitrate nitrogen concentration of root bleeding sap was decreased by 11.11%, the ammonium nitrogen, potassium, and free amino acid concentrations of root bleeding sap under pattern 2 were increased by 32.55%, 17.20% and 19.15%, respectively.’
13) Table 1: In my opinion, Table 1 could be replaced by column graph, as was applied to demonstrate the other results. This maybe improve the comparability of the results.
Response: It was replaced by column graph (Figure 7).
14) L269–274: Which test was applied for analyzing the significance of the regressions (e.g. F test)?
Response: It was applied F test.
15) Fig 7: Range of axes in the graphs should be adjusted to the range of x and y data in order to improve the visibility. Particularly the vertical axis of the top graph should be improved. Otherwise, extrapolation of the regression lines seems to be unreasonable.
Response: It was improved in figure 8.
16) L294–295: “Generally, plants with higher RLD have better water and nutrient absorption efficiency, resulting in higher dry matter accumulation and yield.” It is generally true in a limited environment, but not surely under optimal conditions, considering trade-off between above- and belowground plant organs.
Response: It was improved ‘Under not optimal conditions’.
17) L305: More references are necessary here.
Response: It was added.
18) L307: “The root system is responsible for the absorption and translocation of water and nutrients.” Consider to delete the sentence, it belongs to the introduction.
Response: It was deleted.
19) L309–311: “Therefore, more and thicker roots can absorb more water and mineral nutrients and synthesize more compounds.” More explanation is needed. Thicker roots have smaller surface area in proportion to the root mass.
Response: It was improved ‘for a single nodal root, thicker roots may have more lateral roots and can absorb more water and mineral nutrients and synthesize more compounds’.
20) L321–322: “Maize roots mainly absorb NO3–, part of which is reduced to NH4+ by nitrate reductase and nitrite reductase.” Add a relevant reference to this statement.
Response: It was added ‘Zhang, J., Li, S., Cai, Q., Wang, Z., Cao, J., Yu, T., Xie, T., Exogenous diethyl aminoethyl hexanoate ameliorates low temperature stress by improving nitrogen metabolism in maize seedlings. PLos One. 2020, 15, e0232294’.
21) L329: “A higher potassium concentration can improve lodging resistance”. A brief explanation about the underlying mechanism is needed here.
Response: It was improved ‘A higher potassium concentration can enhance the breaking-resistant strength of stem and improve lodging resistance’.
Author Response File: Author Response.docx
Reviewer 3 Report
The article is interesting and well design under the methodological aspect. Also, the results of all the evaluated parameters are valid for finding a solution to the problem of lodging in maize.
Despite this, authors should improve the discussion section, avoiding repeating too many concepts already expressed in the introduction part and the results.
Please also pay attention to the following points:
- line 105: analyzing RLD we are not able to detect the three-dimensional distribution of roots (i mean spatially) but we can only quantify them (cm per cm3 of soil);
- line 157: why is it interesting to define the number of natural root lodgings? I mean that this parameter was evaluated too late considering the sowing date (1 May) and the length of the vegetation period (120 days).
- figure 4: in my opinion, these graphs can be better understood if the Y-axis values are reported in reverse order under the X-axis and, moreover, using a scatter chart (with points at different depths of the same pattern connected by lines) instead of histograms.
Author Response
The article is interesting and well design under the methodological aspect. Also, the results of all the evaluated parameters are valid for finding a solution to the problem of lodging in maize.
Despite this, authors should improve the discussion section, avoiding repeating too many concepts already expressed in the introduction part and the results.
Please also pay attention to the following points:
- line 105: analyzing RLD we are not able to detect the three-dimensional distribution of roots (i mean spatially) but we can only quantify them (cm per cm3 of soil);
Response: It was improved.
- line 157: why is it interesting to define the number of natural root lodgings? I mean that this parameter was evaluated too late considering the sowing date (1 May) and the length of the vegetation period (120 days).
Response: In order to count the number of all root lodge maize that occurred before harvest, the sampling time was relatively late.
- figure 4: in my opinion, these graphs can be better understood if the Y-axis values are reported in reverse order under the X-axis and, moreover, using a scatter chart (with points at different depths of the same pattern connected by lines) instead of histograms.
Response: It was swapped the X-axis and the Y-axis.
Author Response File: Author Response.docx
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
Manuscript, i.e. experiment is very interesting, giving valuable information about root lodging resistance, including physiological point of view. It also gives practical information how planting pattern and density affect root development and its physiological activity, thus affecting yield potential.
Language should be improved. Some terminology is inappropriate and should be corrected.
Line 38: It would be more proper to use term seed bed instead hole. This should be applied to the whole text (such as line 59-62).
Line 47: Not just amino acids, but whole range of different physiologically active substances that participate in nutrients absorption, provide feed for promoting soil microorganisms etc. Please, include something similar into text.
Line 54-59: There are many repetitions, please, incorporate all these data into one sentence, to avoid repetitions.
Line 73: It would be great to include some additional information about monthly average temperature and precipitation amount, to get impression about any differences between two seasons.
Line 79: Please include information about vegetation period length (no of days), or maturity group.
Line 80: one time fertilizer application
Line 82-83: Please correct accordingly: Plots were randomly arranged, with three replications.
Line 83-85: Please correct accordingly: Plant protection, including herbicide and insecticide application was applied as part of usual practice. Experiment was performed in dry farming conditions.
Line 90-122: Why the same measurements were not included for both years? It is hard to work with roots, especially under the field conditions, but seasonal influences should be included. If eventually the first year served as the base for further, more detailed investigations, provided in the second season, than it is OK, but you must to give additional explanations for this kind of experimental procedure, particularly, since experiment was established in field in dry farming conditions.
Line 107-111, Figure 1: Please show figure 1A and 1B, as four figures, where, two will include experimental design – sowing pattern, while another two figures will show sampling depths, as it was described in the text (line 107-111), since it is hard from figures to understand experimental procedure.
Line 117-118: Why have you firstly dried samples on 105 °C and then on 70 °C, or it was inverse?
Line 121-122: Soil value is inexact term, by the unit of measure it could be concluded that soil volume is considering in formula, so be more precise, change soil value into soil volume.
Line 105-151: To be more precise: Grain yield was measured and calculated to 14% of moisture.
Statistical analysis: Please provide, that you used standard deviation (I’m guessing that) to present some of the data.
Line 158-159: this note should be included into Table and Figure captions, where Anova as method was performed, not here.
Line 164-168: There are unnecessary repetitions again; Both sentences could be integrated into one, to be clearer, since there were no significant differences between patterns 1 and 2 in both parameters.
Figure 3, 4 and 5: Please indicate that bars in figure presents SD (standard deviation, or standard error, if you used this measure).
Parts of the Results titled 3.4 and 3.5 could be integrated into one: Root bleeding sap intensity and its composition at the flowering stage
Line 265: You already mentioned that results are from Table 1.
Results from Table 1 suggests that seasonal influence have significant impact not just on grain yield, but also on root lodging rate and particularly on differences between pattern 1 and 2, that is why some measurements should be included into both years of investigation.
Line 275: Instead of suitable, optimal is more appropriate term.
Line 278: Please exclude higher grain yield, you already mentioned it at the beginning of sentence.
You can exclude mentioning of Tables and Figures in Discussion. All necessary details about them are present in Results, now you discuss them.
Line 276-288 and 289-302: The same text was used twice. Please correct it.
Line 315-316: This sentence is little bit confusing; it seems that in pattern 2 roots tend to be distributed through inter row area.
Experiment is well performed, data are properly analyzed and presented. Discussion should be rewritten, with deeper understanding and connection between data obtained. Conclusion is poor, it should include more information about applicability of results.
Reviewer 2 Report
The manuscript "Planting pattern of wide-narrow row affect roots lodging resistance via regulating root architecture and root-bleeding sap in spring maize" provided by Liu et al. has investigated the effects of planting pattern on grain yield, root morphological traits, root vertical and horizontal distributions, and root bleeding-sap. The authors have mentioned that the planting patterns would increase the grain yield of maize due to the change in the utilization of solar radiation caused by the canopy structural changes although there were not any supporting data.
On the other hands, the authors have investigated the responses of underground traits, reporting that there were statistically significant but very slight changes (e.g., Fig2, Fig 5). In Fig 3 and 4, because the statistical results were not shown in this paper, any descriptions regarding them were just related to the limited study-site specific condition, not to the general pattern under the different planting patterns. The same issue was observed in Fig 7.
Furthermore, the relationships between grain yield and root responses were rarely investigated in this study, indicating that the root responses would not be the reasonable factor regulating plant productivity, so that the conclusion "the planting pattern has a good root architecture" would not be supported only by the current dataset. Besides, the logical description regarding the root lodging in the introduction needs to be verified by some data at least focusing on physical properties whereas the provided data was only the root lodging rate (i.e. table 1).
Overall, the contents of the results were poor to confirm the large part of the mention in this study. Discussion also included the over-speculation (e.g., L296-303, L315-317, 331-332). Therefore, I must mention that those contents in this manuscript were not appropriate for acceptance as an international scientific manuscript. The authors need to reconstruct this study from the basic design as an experiment to verify the effects of root planting pattern on plant productivity and several root traits, where the physiological aspects and the robust sampling design for the optimal statistical methods should be adopted.
The followings are specific comments.
L62: "However,..." This mention would be key for considering the novelty of this study although it was very poor. The more specific relationships between the planting pattern and root physiology should be summarized.
L72: "The total nitrogen,..." Poor description as the section of Material and Methods. The method in detail should be described here. The same issues were often observed in this manuscript (e.g., L84-85, L91, L144, L150.)
Figure 1: Probably due to the low resolution, I cannot check the signs "Partc", "Partd", and so on.
Figure 4 and 5: Were these results statistically tested? If so, where were these results?
Table 1: Why did not the author show SE?
Reviewer 3 Report
This is a review for “Planting pattern of wide-narrow row affect root lodging resistance via regulating root architecture and root-bleeding sap in spring maize(Zea mays L.).”
First of all, I regret to indicate that this manuscript is rejected. The key problems are 1. Implementation of root sampling and experimental design 2. Statistical approach. There are lots of grammar errors and even mistyping issues. However, those are not commented below.
- a) why the direction of row is different? If researchers want to focus on row spacing, they need to exclude other variation. What if this is directional factor rather than row spacing factor?
- b) Implementation of root sampling: I am not understanding how soil digging was implemented with a such small area in 1m depth. 20cmX20cm * 5 sections and 12.5cmX20 * 5 sections in depth. Without loosing soil and maintaining cubic structure.
- c) what is overall structure of experimental design? RCBD? CRD? Line 83 “the process was repeated thrice” what is “the process”? it is not explained.
- d) statistics: which is random/or fixed effect? If it has only two treatments, it must use t test. It is impossible to compare treatments in figure 3 and 4. There is no statistics. No statistics no comparison.
- e) I do not understand why 32.5 to 45.0 part is included.
- f) figure 3, 4 are they error bar? With my root study experience it is highly unlikely happen to have such a small standard error with only three samples in FIELD research.
