Enhanced Nutritional Quality of Sweet Maize Kernel in Response to Cover Crops and Bio-Fertilizer
, Željko Dolijanović 2, Biljana Janosevic 2, Milan Brankov 1, Milovan Stoiljkovic 3, Margarita S. Dodevska 4 and Milena Simić 1Round 1
Reviewer 1 Report
I appreciate the efforts put by the authors to incorporate all my suggestions. but I still feel that the discussion section needs some attention as it is too lengthy and some grammatical errors are there as well. Moreover, the references are not properly formatted as per the author's guidelines provided by the journal.
Author Response
Reply to Reviewer 1:
I appreciate the efforts put by the authors to incorporate all my suggestions. but I still feel that the discussion section needs some attention as it is too lengthy and some grammatical errors are there as well. Moreover, the references are not properly formatted as per the author's guidelines provided by the journal.
Reply:
Thank you for support.
Discussion section was reviewed again, some modifications were done. Also, errors were corrected. References in the List were checked again, accordingly to the Journal guidelines for authors. If some spaces between words, especially in the Reference list are missing, it seems that there is problem between different Windows (Office) versions. We have corrected this kind of errors again and again and it seems that at every document reopening the same errors are present.
Reviewer 2 Report
na
Author Response
Reply to a Reviewer 2
na
Reply:
Thank you for support.
Reviewer 3 Report
1.It is important to clarify the relationship between cropping system and nutritional quality in kernel.
2.Examination design;
(1)Was T7 (organic mulch) the suitable treatment as control? The cover crops (T1-T6) were incorporated in April. The reviewer think T8 (fallow) is control. Wheat residues were laid on ground surface in T7 and T7 was different from other treatments (T1-T6) in over crop management.
(2)Control is important. In the manuscript, there are sentences that the reviewer did not understand what it is compared with. For example, (Line 429)
(Line 429)’while winter oats (T3) + BF enhanced Fe concentration.’ Certainly, Fe concentration in T3+BF was higher than other cover crops with BF, however, same level as T8+BF.
Because of the interactions, complex data were shown. One method is to show the ratio to the control(T8). (for example, 0.85, 1.25…, not Figure)
3.Bio-fertilizer
Detail of bio-fertilizer will be described, how to apply, well-known knowledge (reference) in BF use, Uniker is commercial name? and so on. Reviewer understood that present manuscript has agro-ecological practice. At the same time, mechanism of BF effect will be important. Originally, simple examination (effect of BF on soil quality including mineral content in the soil and so on) will be performed before the present examination.
4.Comments in some important results described in Abstract. Off course, reviewer read all manuscript.
(1)Reviewer checked the data described below on mineral concentrations and anti-nutrients.
(Line 24, reviewer wrote treatment number)
The highest Mg and Mn concentration in maize kernel was achieved with fodder kale (T4/no-BF), Zn concentration with common vetch + winter oats + BF (T5/BF), and Fe concentration with winter oats (T3/no-BF). The same treatments expressed the highest impact on variability in concentration of the phytate, phenolics, and yellow pigment, thus affecting further bio-availability of essential elements.
(2)However, reviewer thinks the following statement does not seem to match the data. Reviewer checked significant difference in kernel yield between BF treatments (BF and no-BF) and kernel yield in BF was larger than no-BF treatment.
(Line 23) BF increased kernel yield, the concentration of sugars, vitamin C, Mg, Fe, Zn, and reduced phytate concentration.
For example, In Figure 3, Fe concentrations of T3(no BF) and T4(no BF) were higher than those of T3(+BF) and T4(+BF).
(3)Effects of cover crop and BF on nutritional quality of kernel will be complex. The reviewer thought that cover crop and BF showed the specific effect on concentrations of nutritional element and anti-nutrients. The reviewer thinks that individual phenomena should be evaluated rather than concluding the effects of cover crops and BF.
5.Principal component analysis
The reviewer understood that Figure 5 showed the loading plot of the explanatory variables and score plot of treatments. The cumulative contribution ratio of PC1 and PC2 was about 47%, not so large. PCA figure will not necessarily have to be included because individual effects of cover crop and BF are more important.
Author Response
Reply to Reviewer 3
Thank you so much for the valuable comments, which helped us so much to improve the manuscript content and style.
1.It is important to clarify the relationship between cropping system and nutritional quality in kernel.
Answer: Sentence was added (line 81-82): The connection between cropping system, yield, and nutritional quality of sweet maize kernel is established in this research. Also, several sentences were added across the text to emphasize this relationship.
2.Examination design;
(1)Was T7 (organic mulch) the suitable treatment as control? The cover crops (T1-T6) were incorporated in April. The reviewer think T8 (fallow) is control. Wheat residues were laid on ground surface in T7 and T7 was different from other treatments (T1-T6) in over crop management.
Answer: Thank you for the valuable comment. We also speculated that organic mulch isnot a proper control, but it also cannot be considered as other CC treatment. As it was described in the manuscript, winter wheat residues covered soil surface during autumn and winter, and in the spring they were incorporated into soil, at the same time when CC biomass was incorporated. Accordingly, modifications in the text were made, to make it clear, including:
T7 –organic mulch;
T8 –control –fallow.
(2)Control is important. In the manuscript, there are sentences that the reviewer did not understand what it is compared with. For example, (Line 429)
Answer: In this sentence we accentuated BF generally impact in regard to all treatments (including the control) without BF application. We have described comparisons between applied treatments and control in Results section, so we tried to avoid unnecessary repetitions in Discussion. Maybe one of the reasons for confusion could lay in the fact that in previous version of manuscript T7 was considered as the one of the control treatments, but actually we mainly compared all applied treatments with fallow (T8). Some corrections were included into Discussion, so we think that text is clearer.
(Line 429)’while winter oats (T3) + BF enhanced Fe concentration.’ Certainly, Fe concentration in T3+BF was higher than other cover crops with BF, however, same level as T8+BF.
Answer: Thank you for pointing, that was a mistake, we have modified sentence into: winter oats (T3) without BF application on Fe increase in maize kernels
Because of the interactions, complex data were shown. One method is to show the ratio to the control(T8). (for example, 0.85, 1.25…, not Figure)
Answer:I agree that results could be shown differently and that effectiveness of treatments in regard to kernel chemical composition (including Pphy, phenolics, GSH, YP, as well as essential elements) could be present as a ratio between treatment and control. Nevertheless, when potential bio-availability is considering, it was established that molar ratio between phytic acid and essential minerals is the main factor that enables bio-availability (accordingly to the great number of previous literature data), while the others factors could also restrain or contribute to the bio-availability, but it seems to a lesser degree (according to the literature, too). Some of the references are used in manuscript.
3.Bio-fertilizer
Detail of bio-fertilizer will be described, how to apply, well-known knowledge (reference) in BF use, Uniker is commercial name? and so on. Reviewer understood that present manuscript has agro-ecological practice. At the same time, mechanism of BF effect will be important. Originally, simple examination (effect of BF on soil quality including mineral content in the soil and so on) will be performed before the present examination.
Answer: Details about BF application (composition and amount) are already present in the text. Yes, Uniker is the commercial name.Mechanism of action is to intensify crop residues, i.e. soil organic matter decomposition, increasing availability of mineral nutrients, as well as enabling production of active compounds that promote plant growth. We have used it in quantity that was recommended by the producer. It is a patented technology and thus, we have provided in M&M description that was present on package. We have analysed soil composition, before CC sowing, before main crop sowing, as well as after harvest of main crop every experimental year, and these data were not included into already long manuscript. We have previous experience with this BF regarding intercropping (reference No. 35) and accordingly to the achieved results we continued and included the same BF into this research.
4.Comments in some important results described in Abstract. Off course, reviewer read all manuscript.
(1)Reviewer checked the data described below on mineral concentrations and anti-nutrients.
(Line 24, reviewer wrote treatment number)
The highest Mg and Mn concentration in maize kernel was achieved with fodder kale (T4/no-BF), Zn concentration with common vetch + winter oats + BF (T5/BF), and Fe concentration with winter oats (T3/no-BF). The same treatments expressed the highest impact on variability in concentration of the phytate, phenolics, and yellow pigment, thus affecting further bio-availability of essential elements.
Answer: Thank you for the suggestion, but we did not include shortcuts, describing treatments, previously in abstract (line 18-19), due to the intention to make understandable and easier to readers to see how applied treatments impact chemical composition of sweet maize kernel.
(2)However, reviewer thinks the following statement does not seem to match the data. Reviewer checked significant difference in kernel yield between BF treatments (BF and no-BF) and kernel yield in BF was larger than no-BF treatment.
Answer: Yes, we have mentioned that BF expressed effect on average kernel yield increase (line 23, as well as part of the text in Results and Discussion), there is no mention that no-BF treatment induced so.
(Line 23) BF increased kernel yield, the concentration of sugars, vitamin C, Mg, Fe, Zn, and reduced phytate concentration.
For example, In Figure 3, Fe concentrations of T3(no BF) and T4(no BF) were higher than those of T3(+BF) and T4(+BF).
Answer: Yes, that is an interaction CC + BF, while BF in average increased Fe concentration (Table 4).
(3)Effects of cover crop and BF on nutritional quality of kernel will be complex. The reviewer thought that cover crop and BF showed the specific effect on concentrations of nutritional element and anti-nutrients. The reviewer thinks that individual phenomena should be evaluated rather than concluding the effects of cover crops and BF.
Answer: I agree that it is hard to follow the multifactorial impact on kernel yield and its chemical composition, particularly when further potential bio-availability is considered. But in contemporary agricultural science multifactorial design is more important for measuring plant response, so appropriate statistics is helpful tool to distinguish plant/crop answer. Individual response are present in Table 4, as ANOVA analysis, further complexity was aimed to show connection between low-input cropping practices and nutritional quality of produced kernels.
5.Principal component analysis
The reviewer understood that Figure 5 showed the loading plot of the explanatory variables and score plot of treatments. The cumulative contribution ratio of PC1 and PC2 was about 47%, not so large. PCA figure will not necessarily have to be included because individual effects of cover crop and BF are more important.
Answer: Contribution of all four axes is 75%. While Table 4 shows contribution of individual effects - sources of variability on kernel composition, Figure 5 is aimed to show,not only variability in chemical composition of sweet maize kernel, but interdependence between applied CC, as well as CC+BF treatments and kernel composition, regarding essential elements and factors that restrain or contribute to their bio-availability. This analysis pointed effectiveness of applied treatments (CC, BF, no-BF) and gives opportunity to show possibility to mutually increase concentration of essential elements and promoters, with parallel reduction of anti-nutrients, what was discussed.
Round 2
Reviewer 3 Report
The reviewer understood the authors obtained much data and tried to evaluate the effect of CC and BF on kernel nutrient quality by using statistical analysis for providing the useful information to agriculture practice.
It was suitable that organic mulch was a kind of cover crop use.
As to BF, the reviewer checked the literature [35] and advise that the literature [35] will be placed in Materials and Methods because the application of BF was written in [35]. BF is called soil amendment, not fertilizer, in reviewer’s country.
Author Response
Reply to Reviewer 3
The reviewer understood the authors obtained much data and tried to evaluate the effect of CC and BF on kernel nutrient quality by using statistical analysis for providing the useful information to agriculture practice.
Answer: Thank you for the comment, our intention was to emphasize sustainable practices (CC and BF) as potential sources of enhanced quality of sweet maize kernel.
It was suitable that organic mulch was a kind of cover crop use.
Answer: We already attributed organic mulch as T7, one of the CC treatments, while T8 – fallow, presents control treatment.
As to BF, the reviewer checked the literature [35] and advise that the literature [35] will be placed in Materials and Methods because the application of BF was written in [35]. BF is called soil amendment, not fertilizer, in reviewer’s country.
Answer: We are not producers or authors of the mentioned BF, we only used it in several experiments, so we consider not citing reference 35 (now ref. 37) in M&M section. Reference 35 (37) describes results obtained by application of fertilizer on maize and soybean intercrops.
It is great and valuable that BF are used as soil amendment (personally I think that should be worldwide strategy), but Agronomy is an International Journal, so BF could be considered as one of the applied treatments (fertilizer treatment, by definition) in this experimental trial.
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
The manuscript “Enhanced nutritional quality of sweet maize kernel in response to cover crops and bio-fertilizer” by Dragicevic, et al., talks about the impact of different cover crops and bio-fertilizer (BF) application, on the yield and quality of sweet maize kernel.
Overall, this manuscript is well written and thoroughly described. However, the language used in the manuscript is not up to the standard for publication, and several major and minor grammatical mistakes are shown, and many of the phrases are not clear. It should go through a complete proof-reading by a native speaker. A few examples from only the abstract section are mentioned below (in bold letters), while it is the same case for the overall manuscript.
Line 14: Cover crops (CC) are an important low-input strategy
Line 22: BF increased kernel yield, the concentration
Line 26: The same treatments expressed the highest impact on variability in the concentration of phytate
Line 28: Results indicate that in a semi-arid climate, under rain-fed conditions
Line 31: an important part of a sustainable cropping system
The introduction section should be revised properly as there are many irrelevant statements in this section. At the end of the introduction section, mention the significance of the experiment for future prospects in a single sentence.
2.1. plant material; BF treatment is missing in this section. It is better to mention the treatments in tabular format in order to make them easily understandable
Line 173: Perten 120 – Sweden: provide complete information of the manufacturer with its city and country names
Maize is a very important cereal crop regarding its food, feed, biofuel & oil quality, and its relatively lower yield and production due to different factors is a very interesting issue to be discussed and the authors have put much work into exploring it, by applying different cover crops with different BF treatments, which is one-of-a-kind techniques to enhance its production and quality. The findings of the study can also pave a road towards successive use of other mineral elements in yield and production attributes of other different staple food crops as well. However, some aspects of the manuscript need attention. A significant weakness of this manuscript is too lengthy discussion part. The results and Discussion section needs some serious revisions, the authors should provide more precise and strong justifications to support the arguments/results obtained during the experiments. Moreover, there are many sentences and grammatical errors throughout this section as well.
The references are not properly formatted as per the author’s guidelines, regarding authors' names, abbreviated names of the journals, etc.
In summary, presented data show a positive scenario regarding physio chemical activities, but the discussion of results is very speculative. To sum up, the manuscript can find interest among specialists when these comments will be taken into account.
Good Luck!
Reviewer 2 Report
Exactly what is the BF treatment and how is it quantified? Without that I cannot recommend. Anova tables not needed. Mean separations LSDs required. Paper is opinionated with regard to lit review. Words taken out of context.
Reviewer 3 Report
Introduction
The role of cover crop was described very well.
The main research subject is nutritional quality (composition) in the kernel in sweet corn produced with cover crops and bio-fertilizer for 3 years. There were 3 factors in the examination, cover crops, bio-fertilizer and year.
In the nutritional quality in corn kernel, the importance of both minerals (including promoters) and anti-nutrient (phytic acid, phenolics) was pointed out. However, hypothesis on the relation between cover crop and nutritional quality was not described. There is no such reference. The relation between bio-fertilizer and anti-nutrient substances was explained citing the Reference [33]. However, there was no result on phytic acid in the reference [33]. The reviewer thinks the rationale for setting up this experiment is unclear.
If my understanding on reference [33] was not correct, the reviewer has to apology.
Materials and Methods
What was the materials of dead mulch?
Nitrogen fertilizer; What kind of N fertilizer was used? Do authors have the data on nitrogen fixing amount? How about the mineralization rate of incorporated legume crops and non- legume crops? Usually, CC growth was evaluated in the field with no or small amount of N fertilizer.
As to chemical analysis, when (which year) did authors collect the kernel samples?
Results
Statistical significance in CC biomass and kernel yield was shown in all factors and all interactions and the results were very complex. Same situation was shown in nutritional contents in kernel. It was difficult to evaluate the factor effect and more simple design of examination will be considered.
In Figure 1-4, lines will be removed values of x-axis (T1 to T8) are not continuous variables.
In Figure 5, is there new analysis technology in PCA? Usually, scatter plot graph will be made for evaluation.
Discussion
Reviewer thinks too long. As pointed out in Introduction, a clear research objective and examination design should be set and considered.
Reference
Too many.
