Nutritional Value of Whole Maize Kernels from Diverse Endosperm Types and Effects on Rheological Quality

Round 1

Reviewer 1 Report

The manuscript is devoted to an interesting and important subject of nutritional and bread making quality of different types of maize. The study is based on solid results obtained from two sites in two years. The paper is well written and provides mostly sufficient results and arguments for the main conclusions. However, it may be improved by attending the following issues:

1. Introduction is very short and justifies a short explanation of the role of maize as food for people in Spanish and European context.
2. The data from lower part of table 2 with mean % can be presented as bar graphs for better visualization.
3. Table 3 combines two tables. They can be separated or they can also can be combined into side by side table by removing the least important traits and focusing on the key traits defining the quality.
4. Section correlation shall be renamed to “Correlations between nutrition traits” and Regression respectively to “Regression of nutrition and bread making traits.”
5. The term “minerals” raises question of what minerals. This term probably means ash.
6. Table 4 is unacceptable being half empty with several rows completely empty. The focus can be ion most significant regressions probably presented as graphs and the rest explained in the text. Generally, biplot analysis is much better approach to demonstrate the multiple traits relationship instead of regressions.
7. The reference to relation between the quality and agronomic performance is not relevant due to the fact that agronomic performance data is not presented at all.
8. The important issue of the stability of bread-making traits is not covered though the authors have data from four trials. How variable the traits and they relationships depending on the site and year? In this respect the weather conditions and yield level of maize across sites and years need presentation. The data in Table 4 probably based on mean values which has to be stated. Mean values can mask important variations.
9. Discussion is too focused on the results instead of giving as broad view as possible of the study outcome and impact. The subject of nutrients in different maize types is well studied. However, their effect on bread quality is much less and this represents novel topic. The breads photos would be used to present in paper or as supplement.
10. The scientific language can be improved to avoid the sentences like below: “However, improving nutrient content could alter agronomic performance because nutrients had significant effects on rheological factors, being mainly negative the effects of protein and lipid on whole meal and on bread characteristics.” There are several statements in this sentence which are difficult to understand.

Author Response

1. Introduction is very short and justifies a short explanation of the role of maize as food for people in Spanish and European context.

R: We have added a paragraph about that at the beginning of the introduction

1. The data from lower part of table 2 with mean % can be presented as bar graphs for better visualization.

R: We have added a figure with those data

1. Table 3 combines two tables. They can be separated or they can also can be combined into side by side table by removing the least important traits and focusing on the key traits defining the quality.

R: We have separated table 3 in two tables (3 and 4)

1. Section correlation shall be renamed to “Correlations between nutrition traits” and Regression respectively to “Regression of nutrition and bread making traits.”

R: We have modified both headings following the reviewer request

1. The term “minerals” raises question of what minerals. This term probably means ash.

R: We have replaced “minerals” by “ash”, according to the reviewer correction

1. Table 4 is unacceptable being half empty with several rows completely empty. The focus can be ion most significant regressions probably presented as graphs and the rest explained in the text. Generally, biplot analysis is much better approach to demonstrate the multiple traits relationship instead of regressions.

R: We have removed table 4 and include that information in the text, for avoiding too many figures, as there the revised version has already two figures suggested by the reviewer

1. The reference to relation between the quality and agronomic performance is not relevant due to the fact that agronomic performance data is not presented at all.

R: Although we had made correlations between nutrients and agronomic traits, and we believe they could be interesting for breeders, we have removed that paragraph following the request of the reviewer

1. The important issue of the stability of bread-making traits is not covered  though the authors have data from four trials. How variable the traits and they relationships depending on the site and year? In this respect the weather conditions and yield level of maize across sites and years need presentation. The data in Table 4 probably based on mean values which has to be stated. Mean values can mask important variations.

R: The stability of bread-making traits was already published in a previous article, see reference [8] (Revilla et al 2019). In that article we found that the quality traits were quite stable across years and locations, as the significant genotype × environment interactions were of magnitude rather than of rank. Furthermore, as stated in the current manuscript, few interactions were significant and they were of magnitude. Therefore, we considered that the stability of these quality traits was acceptable from a breeder’s perspective.

We have added, in section 2.3 (Statistical analyses), that regressions were made with the mean values. Indeed means could mask important variations if there were other factors with important effects; however, as genotypic diversity was the major factor in this case, because the maize mutants were chosen on purpose to maximize genetic diversity, we used the means of hybrids.

1. Discussion is too focused on the results instead of giving as broad view as possible of the study outcome and impact. The subject of nutrients in different maize types is well studied. However, their effect on bread quality is much less and this represents novel topic. The breads photos would be used to present in paper or as supplement.

R: We have added some sentences and paragraphs about factors affecting flour and bread quality; though, as the reviewer says, the effects of nutrients in flour and bread quality is a novel topic and we have not found additional references clearly related with this question.

We have added a figure with photos of grain, flour and bread in methods

1. The scientific language can be improved to avoid the sentences like below: “However, improving nutrient content could alter agronomic performance because nutrients had significant effects on rheological factors, being mainly negative the effects of protein and lipid on whole meal and on bread characteristics.” There are several statements in this sentence which are difficult to understand.

R: We have modified that sentence and reviewed the rest of the text once again

Reviewer 2 Report

1. The data of scientific papers need analysis of variance.
2. The research content is too simple. Please further study the classification of protein and dietary fiber to better explore the correlation
3. Correlation coefficient use r, not R² in table 4.
4. Please add the discussion about maize rheological traits on nutrients’ content, not simply list the data.

Author Response

1. The data of scientific papers need analysis of variance.

R: The statistical analyses of this study include comparisons of means, correlations and regressions. We have used the analyses of variance only for calculating the errors for mean comparisons because we used the Fisher’s protected LSD; however, we could have used other methods for comparisons of means that do not require analyses of variance. Therefore, analyses of variance are not relevant here.

2. The research content is too simple. Please further study the classification of protein and dietary fiber to better explore the correlation

R: As the first reviewer says, the objective of this work is quite original. Indeed, no previous report has shown the effects of nutrients on rheological traits in maize. This objective could be simple, though it involves knowing the nutritive value of maize genotypes from four endosperm types of maize, and the relationship between nutrient concentration and agronomic and rheological values. Of course, we could do more, and specialist in several disciplines could deeply study diverse aspects; but this information is valuable and interesting enough for breeders.

3. Correlation coefficient use r, not R² in table 4.

R: The R² of table 4 is not a correlation coefficient, but a coefficient of determination. Now that we have removed table 4, following the request of reviewer 1, the term is included in the text.

1. Please add the discussion about maize rheological traits on nutrients’ content, not simply list the data.

R: We have added concluding sentences in the discussion. Besides, we have expanded the discussion with some related previous studies which show that the effects of nutrients on rheological traits are not consistent and stable across genotypes. Apparently, different combinations of nutrients result in diverse rheological performance, and other factors must affect rheological performance more strongly than nutrients. We believe we have said as much as we can say with the currently available data.

Round 2

Reviewer 2 Report

Please add variance analysis.