Seed Halo-Priming Improves Seedling Vigor, Grain Yield, and Water Use Efficiency of Maize under Varying Irrigation Regimes

Round 1

Reviewer 1 Report

This paper evaluates impacts of halo-priming on several growth and yield attributes of maize. The water usage and distribution among various food production system is diverse across all agro-ecological zones. The management strategies and allocation policies for different stakeholders largely depend on water resource availability and its end use goal specially in arid and semi-arid regions. Authors highlighted halo priming as promising approach to avoid drought stress or mitigate at some extent, which needs to be replicated for multiple locations and years.

Major comments:

Abstract: At the beginning, please add couple of line to set the context in abstract to introduce what author is trying to convey.

Introduction: Authors missed to highlight the recent development in drought mitigation measures in Introduction section. Hypothesis is not defined clearly.

Methodology: In statistical analysis DMRT will strengthen the analysis. Significance among treatments were not explained properly.

Discussion: There was lack of recent literature to support and counter the finding. Discussion is superficial without any explanation on the physiological/biophysical attributes of drought impacts on crop

Conclusion: Conclusion can be improved with future implications of this work.

References: Please double check doi of all references.

Here are specific comments:

Line 11: delete thenceforth: It mean after that time. Please use hence.

Line  14:  yield, and water…

Line 18: When Using ET_c first time put acronym

Line 22: Replace speed with rate

Line 40: While changing paragraphs, please connect the story. It should not be stand alone

Line 41: area is

Line 42: Production of about

Line 45-48: Please cite recent literature on water stress and root growth in maize (Jha, Prakash Kumar, Amor VM Ines, and Maninder Pal Singh. "A multiple and ensembling approach for calibration and evaluation of genetic coefficients of CERES-maize to simulate maize phenology and yield in Michigan." Environmental Modelling & Software 135 (2021): 104901.

Line 54: replace as with like

Line 55: replace accordingly with subsequently

Line 56: merge with earlier paragraph

Line 58: potential of seeds, which is similar to drought stress impacts

Line  153: 2.2.4.

Line 188: Please rearrange this line

 

 

Author Response

Dear Editor,

Enclosed please find the revised version of our manuscript entitled “Influence of Halo-Priming on Seedling, Grain Yield and Water Use Efficiency of Maize Under Varying Irrigation Regimes” (Manuscript ID: water-1307182). With this letter, we would like to thank you and the reviewers for providing clear and constructive suggestions that gave us the opportunity to improve the quality of the manuscript. After carefully reading all comments provided, a major revision of the manuscript is carried out to fulfill the required suggestions.

Yours sincerely,

Authors

Responses to Reviewers Comments

Reviewer 1:

This paper evaluates impacts of halo-priming on several growth and yield attributes of maize. The water usage and distribution among various food production system is diverse across all agro-ecological zones. The management strategies and allocation policies for different stakeholders largely depend on water resource availability and its end use goal specially in arid and semi-arid regions. Authors highlighted halo priming as promising approach to avoid drought stress or mitigate at some extent, which needs to be replicated for multiple locations and years.

Re: We would like to thank the reviewer for his time dedicated to our manuscript.

Major comments

Abstract

At the beginning, please add couple of lines to set the context in the abstract to introduce what the author is trying to convey.

Re: Thanks for the suggestion, a sentence has been added (please see lines 13-14)

Introduction

Authors missed to highlight the recent development in drought mitigation measures in Introduction section. Hypothesis is not defined clearly.

Re: More details have been added in lines 50-54 and the hypothesis has been defined in lines 72-75.

Methodology

In statistical analysis DMRT will strengthen the analysis. Significance among treatments were not explained properly.

Re: The least significant difference (LSD) at P ≤ 0.05 was used to separate the differences among treatments, has been added in lines 164-165.

Discussion

There was lack of recent literature to support and counter the finding. Discussion is superficial without any explanation on the physiological/biophysical attributes of drought impacts on crop

Re: The literature has been updated and the physiological attributes of drought impacts on maize have been added (please see lines 335-337)

Conclusion

Conclusion can be improved with future implications of this work.

Re: The conclusion has been revised and future implication has been suggested (lines 424-425)

Here are specific comments:

Line 11: delete thenceforth: It mean after that time. Please use hence.

Re: Done (line 12)

Line  14:  yield, and water…

Re: Done (line 14)

Line 18: When Using ETc first time put acronym

Re: Done (line 19)

Line 40: While changing paragraphs, please connect the story. It should not be stand alone

Re: The two paragraphs have been merged (38-41)

Line 41: area is

Re: Done (line 41)

Line 42: Production of about

Re: Done (line 42)

Line 45-48: Please cite recent literature on water stress and root growth in maize (Jha, Prakash Kumar, Amor VM Ines, and Maninder Pal Singh. "A multiple and ensembling approach for calibration and evaluation of genetic coefficients of CERES-maize to simulate maize phenology and yield in Michigan." Environmental Modelling & Software 135 (2021): 104901.

Re: Done (line 46)

Line 54: replace as with like

Re: Done (line 59)

Line 55: replace accordingly with subsequently

Re: Done (line 60)

Line 56: merge with earlier paragraph

Re: Done (line 61)

Line 58: potential of seeds, which is similar to drought stress impacts

Re: Done (line 64-65)

Line  153: 2.2.4.

Re: has been numbered to be 2.3. (line 161)

Line 188: Please rearrange this line

Re: Done (line 200)

Author Response File: Author Response.docx

Reviewer 2 Report

General comments

Dear Authors,

I did enjoy going through this manuscrip and acknowledge its good quality becuase of the simplicity and the well structured writing.

There are two aspects that to me understanding need improvement. Firstly, you need to provide more details on the statistical analyses as well as to specify the R packages used. Secondly, the addition of a principal components analysis is great as it just reinforces all the results presented previously with an analysis that account for the overall effects; haven't said that, you do please need to extend more the information that the PCA plot gives.

Overall, I find this manuscript well presented. Please, consider to follow the recommendation pointed out below and some editions provided in the PDF file.

Specific comments

Title. The title has the relevant words and is informative about what has been done in this research. In view of the promising findings, I suggest to be explicit in the title by changing, for example,  the word ‘influence’ by ‘improvements’. For example: ‘Improvements of seed halo-priming on maize seedling, grain yield and water use efficiency under varying irrigation regimes’.

Introduction.

-Please, carefully revise the paragraphs where seed priming (lines 50-55) and seed halo-priming are defined (lines 56-64) and rephrase them accordingly. These definitions should be impeccable and from my view are not clear enough.

Methods.

This section is well structured and informative. However, the statistical analyses section is incomplete. I recommend the following:

• Please, provide details about the analyses performed to produce results from table 3.
• Please, provide details about how the response curves of grain yield of figure 4 were produced. Also, tt is unclear how was determined the so-called irrigation ‘optimum’. You need to explain what this ‘optimum’ means and how it tights up with the irrigation regimes used in the experiment. Is it 757 mm equal to the 100% EVc? Maybe this is state somewhere and you just need to make it more prominent.
• Please state –what R packages were used and provide the corresponding citation as well as specify the R version.

Results.

Table 3. The caption of the table is incomplete.

Lines 162-165. When explaining the effects of the halo-priming treatment on germination-related parameters, you refer to a certain percentage of improvement compared with unprimed seeds. Unfortunately, as germination-related parameters are expressed in %, the statement is confusing. You my rephrase this with something like ‘Compared with unprimed seeds that had 80% of germination percentage and 8.62 germination index (Table 3), halo-primed seeds at 4000ppm reached 93.3% of germination and a germination index of 18.06 that represent a 16.7% and 109% increase in these parameters, respectively.’ Please, you need to point out that the improvements in germination-related parameters are statistically significant supporting that the 4000ppm NaCl treatment significantly improved maize seedling. For example, ‘The stimulating impact of the halo-priming treatment at a level of 4000ppm NaCl was statistically significant.

Figure 2. Please, correct the label for 80% irrigation.

3.2. Lines 212-227. Interactions: I find great the start of this paragraph with a general (the big picture) statement. Some editing is recommended below:

• Lines 214-215. “Generally, excessive irrigation did produce significant increase in grain yield and its tributes under any seed halo-priming treatment.” This reads as if the 120% irrigation treatment had increased yields, etc., which is not the case. You probably meant that ‘did not produce significant increase…’. Please, rephrase it for clarity. For example: ‘Regardless seed treatment, no significant effects were observed in grain yield and its related attributes with a 20% increase of irrigation above ETc’. Looking at the results presented (Tables 4, 5 and fig. 2 and 3), it seems very clear that regardless seed treatment (i.e. control, 4000ppm, 8000ppm halo-priming) there were not significant differences nor interaction effects for any measured trait (except WUE) under 100% and 120% irrigations regimes.
• Lines 215-217. “The impact of halo-primed treatments was not significant under well-watered conditions (120 and 100%ETc) while was more pronounced under severe and moderate drought stress (60% and 80% ETc)”. These are two outstanding findings and I suggest making two separate sentences, for example: “The impact of halo-primed treatments was not significant under well-watered conditions (120% and 100%ETc). Under moderate and severe water scarcity (80% and 60%), the positive effect of seed halo-priming treatments were statistically significant and plants from treated seeds showed smaller reductions in yield-related traits and increased WUE (Fig. 3F)’.

3.2.1. Lines 240-251. Grain yield.

There is interesting information here, however, you missed to explain in methods how the response equations were calculated and how the optimum of 757 mm was determined. Please, you need to provide details about this in methods.

3.2.2 Lines 253-264.

The PCA can be an interesting source of information; however, this paragraph does not completely point it out. I suggest to present PCA results starting with the explanatory variables (interpretation of axes) and then by the implications in the response variables.

• For a PCA, it is crucial to first understand what axis 1 and axis 2 mean in terms of explanatory variables. Apparently, axis 1 explained ~81% variation and is controlled by the irrigation regime increasing from 60% to 100% irrigation. The increase from 100% to 120% had small effect as it is depicted by the small distance of plots from these treatments along axis 1. Axis 2 explained ~17% variation and seems to correspond to the seed treatments, from unprimed to 4000ppm treatment.
• As explained and as expected from the results previously presented, yield grain and related traits are positively correlated and opposite to WUE. So, the PCA is reinforcing previous results. This is well explained
• An aspect missing is the discussion of the distance in the multi-dimensional space of PCA between the dots that represent each treatment. For example, dots representing the irrigation regimes of 120% and 100% are close together in the bottom right quadrant and in the top right quadrant, respectively. While those of the 60% and 80% irrigation regimes are much more spread out implying dissimilarity. As irrigation regimes is reduced, seed treatments are more dissimilar with plots under 60% irrigation being the most dissimilar plots)
• Regardless the irrigation regime, seed treatments are ordered from bottom to top as unprimed, 8000ppm and 4000ppm following an increase of WUE.
• While yield-related traits are associated to axis 1 (mostly), WUE is associated to both axes but predominantly with axis 2.
• While WUE increases towards the top left of the figure, treatments within an irrigation regime increase towards the top right in an almost 90 degrees direction to WUE.

Discussion

From my point of view, the discussion is well structured and it provides excellent contrasts with previous research. Something I wonder is whether the level of 4000ppm of NaCl halo priming is adequate. It would be interesting to know if there is research that investigated different levels of priming in maize. You might consider including a few more citation of halo-priming specific for maize. For example, "Influence of seed invigoration techniques on germination of maize" DOI: 10.1515/cerce-2017-002

Comments for author File: Comments.pdf

Author Response

Dear Editor,

Enclosed please find the revised version of our manuscript entitled “Influence of Halo-Priming on Seedling, Grain Yield and Water Use Efficiency of Maize Under Varying Irrigation Regimes” (Manuscript ID: water-1307182). With this letter, we would like to thank you and the reviewers for providing clear and constructive suggestions that gave us the opportunity to improve the quality of the manuscript. After carefully reading all comments provided, a major revision of the manuscript is carried out to fulfill the required suggestions.

Yours sincerely,

Authors

 

Responses to Reviewers Comments

Reviewer: 2

Dear Authors,

I did enjoy going through this manuscript and acknowledge its good quality because of its simplicity and well-structured writing. There are two aspects that to me understanding needs improvement. Firstly, you need to provide more details on the statistical analyses as well as to specify the R packages used. Secondly, the addition of a principal components analysis is great as it just reinforces all the results presented previously with an analysis that accounts for the overall effects; haven't said that, you do please need to extend more the information that the PCA plot gives. Overall, I find this manuscript well presented. Please, consider to follow the recommendation pointed out below and some editions provided in the PDF file.

Re: We would like to thank the Reviewer for his time dedicated to our manuscript and presenting positive aspects in our manuscript. The used R packages have been added (lines 163 and 170) and more explanations have been added for PCA biplot (lines 273-297).

Specific comments

Title: The title has the relevant words and is informative about what has been done in this research. In view of the promising findings, I suggest to be explicit in the title by changing, for example,  the word ‘influence’ by ‘improvements’. For example: ‘Improvements of seed halo-priming on maize seedling, grain yield and water use efficiency under varying irrigation regimes’.

Re: Thanks for the suggestion, the title has been modified as suggested

Introduction

Please, carefully revise the paragraphs where seed priming (lines 50-55) and seed halo-priming are defined (lines 56-64) and rephrase them accordingly. These definitions should be impeccable and from my view are not clear enough.

Re: The paragraph has been revised and the definitions have been cleared (please see lines 55-65)

Methods

This section is well-structured and informative. However, the statistical analyses section is incomplete. I recommend the following:

Please, provide details about the analyses performed to produce results from table 3.

Re: More details have been added in lines 163-165

Please, provide details about how the response curves of grain yield of figure 4 were produced. Also, it is unclear how was determined the so-called irrigation ‘optimum’. You need to explain what this ‘optimum’ means and how it tights up with the irrigation regimes used in the experiment. Is it 757 mm equal to the 100% ETc? Maybe this is state somewhere and you just need to make it more prominent.

Re: Please see lines 167-169 and 258-260

Please state –what R packages were used and provide the corresponding citation as well as specify the R version.

Re: The packages, citations, used version have been added (lines 163 and 170)

Results

Table 3. The caption of the table is incomplete.

Re: The caption has been modified

Lines 162-165. When explaining the effects of the halo-priming treatment on germination-related parameters, you refer to a certain percentage of improvement compared with unprimed seeds. Unfortunately, as germination-related parameters are expressed in %, the statement is confusing. You may rephrase this with something like ‘Compared with unprimed seeds that had 80% of germination percentage and 8.62 germination index (Table 3), halo-primed seeds at 4000ppm reached 93.3% of germination and a germination index of 18.06 that represent a 16.7% and 109% increase in these parameters, respectively.’ Please, you need to point out that the improvements in germination-related parameters are statistically significant supporting that the 4000ppm NaCl treatment significantly improved maize seedling. For example, ‘The stimulating impact of the halo-priming treatment at a level of 4000ppm NaCl was statistically significant.

Re: Modifications have been done as suggested, please see lines 173-181

Figure 2. Please, correct the label for 80% irrigation.

Re: The label for 80% irrigation has been corrected

3.2. Lines 212-227. Interactions: I find great the start of this paragraph with a general (the big picture) statement. Some editing is recommended below:

Lines 214-215. “Generally, excessive irrigation did produce significant increase in grain yield and its tributes under any seed halo-priming treatment.” This reads as if the 120% irrigation treatment had increased yields, etc., which is not the case. You probably meant that ‘did not produce significant increase…’. Please, rephrase it for clarity. For example: ‘Regardless seed treatment, no significant effects were observed in grain yield and its related attributes with a 20% increase of irrigation above ETc’. Looking at the results presented (Tables 4, 5 and fig. 2 and 3), it seems very clear that regardless seed treatment (i.e. control, 4000ppm, 8000ppm halo-priming) there were not significant differences nor interaction effects for any measured trait (except WUE) under 100% and 120% irrigations regimes.

Re: the sentence has been rephrased as suggested please see lines 225-226

Lines 215-217. “The impact of halo-primed treatments was not significant under well-watered conditions (120 and 100%ETc) while was more pronounced under severe and moderate drought stress (60% and 80% ETc)”. These are two outstanding findings and I suggest making two separate sentences, for example: “The impact of halo-primed treatments was not significant under well-watered conditions (120% and 100%ETc). Under moderate and severe water scarcity (80% and 60%), the positive effect of seed halo-priming treatments were statistically significant and plants from treated seeds showed smaller reductions in yield-related traits and increased WUE (Fig. 3F)’.

Re: The sentence has been rephrased as suggested please see lines 229-232

3.2.1. Lines 240-251. Grain yield.

There is interesting information here, however, you missed to explain in methods how the response equations were calculated and how the optimum of 757 mm was determined. Please, you need to provide details about this in methods.

Re: More details have been added please see lines 257-260

3.2.2 Lines 253-264.

The PCA can be an interesting source of information; however, this paragraph does not completely point it out. I suggest to present PCA results starting with the explanatory variables (interpretation of axes) and then by the implications in the response variables. For a PCA, it is crucial to first understand what axis 1 and axis 2 mean in terms of explanatory variables. Apparently, axis 1 explained ~81% variation and is controlled by the irrigation regime increasing from 60% to 100% irrigation. The increase from 100% to 120% had small effect as it is depicted by the small distance of plots from these treatments along axis 1. Axis 2 explained ~17% variation and seems to correspond to the seed treatments, from unprimed to 4000ppm treatment. As explained and as expected from the results previously presented, yield grain and related traits are positively correlated and opposite to WUE. So, the PCA is reinforcing previous results. This is well explained. An aspect missing is the discussion of the distance in the multi-dimensional space of PCA between the dots that represent each treatment. For example, dots representing the irrigation regimes of 120% and 100% are close together in the bottom right quadrant and in the top right quadrant, respectively. While those of the 60% and 80% irrigation regimes are much more spread out implying dissimilarity. As irrigation regimes is reduced, seed treatments are more dissimilar with plots under 60% irrigation being the most dissimilar plots). Regardless the irrigation regime, seed treatments are ordered from bottom to top as unprimed, 8000ppm and 4000ppm following an increase of WUE. While yield-related traits are associated to axis 1 (mostly), WUE is associated to both axes but predominantly with axis 2. While WUE increases towards the top left of the figure, treatments within an irrigation regime increase towards the top right in an almost 90 degrees direction to WUE.

Re: The paragraph has been improved as suggested please see 273-297

Discussion

From my point of view, the discussion is well structured and it provides excellent contrasts with previous research. Something I wonder is whether the level of 4000ppm of NaCl halo priming is adequate. It would be interesting to know if there is research that investigated different levels of priming in maize. You might consider including a few more citation of halo-priming specific for maize. For example, "Influence of seed invigoration techniques on germination of maize" DOI: 10.1515/cerce-2017-002.

Re: The discussion has been revised, suggested citation has been added (line 358), and another study with different halo-priming levels has been discussed (lines 365-370).

We deeply thank you for your support and efforts to improve our manuscript

Yours sincerely,

Authors

Author Response File: Author Response.docx