Biofertilizers Enhance Quality of Onion
Round 1
Reviewer 1 Report
The manuscript provides interesting data about the effect of application of organic fertilizers on the composition of two onion cultivars in Czech Republic during 3 years. It is focuses on antioxidant activity, content of chlorophylls, crude fibre and Zn in the onion cultivars. The manuscript is generally well written, methods adequately implemented and results appropriately presented.
My comments are:
Figure 2: I suggest to sign the first columns in the graph for better understanding of the results.
Line 103: Please correct the superscripts in the text (HNO3+2 ml ….)
Line 204: Please replace “Figure 8” by “Figure 7”
If you compared all parameters in the correlation analyses, I wonder whether you have found any other significant correlation coefficient between the data, such as for example correlation between Zn content and antioxidant activity.
I am not really sure why you decided to investigate only Zn content in onions either from your Introduction or Discussion, due to its toxicity as a heavy metal or Zn essentiality as a trace element? Did you expected higher concentration of Zn in the onion cultivars based on used organic fertilization? Could you please clarify your purpose investigating Zn content in the Introduction. Onion can improve bioavailability of Zn and Fe from food grains due to its higher content of sulfur-containing compounds, but on the other hand, the different content of crude fibre in the onion cultivars could affect the mineral bioavailability differently. Please try to discuss this topic with your finding in the section Discussion.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors described the study about Biofertilizers enhance the quality of onion. The references could be definitely improved, look for example Yogita & Ram 2012. Moreover, I would suggest improving by more information about the procedure methods. E.g., was the experiment conducted in a greenhouse? Did you use some artificial light? Did you make some chemical analyses of the soil to detect how the biofertilizers improving the soil structure?
Cyanobacteria and green algae are recognized for their diverse roles in sustainable agriculture such as biostimulation, N fertilization, biocontrol, etc. (Renuka et al., 2018). Did you think to use a consortium of these organisms?
How and how much did you add the different biofertilizers? Did you use dry Chlorella biomass? Where did you buy it?
Finally, which is the major contribution that this manuscript has in the respect of your previous one published in 2019 (DOI:10.15244/pjoes/99909)?
Hereafter, some issues arisen during reading:
Page 1, lines 25-26: in my opinion, this sentence may easily merge into one to streamline the text;
Page 1, lines 35-36: the sentence sounds unclear to me; did you mean “to human food...” perhaps? In the same sentence, it should be “leads” instead of “lead”;
Page 2, lines 72-78: please, could the authors indicate the relative proportion of each component forming B-Stimul and Vermifit A fertilizers? If those are commercial products and not experimental blends, please make it explicit;
Page 4, lines 118-122: please, could the authors clarify if the fertilizer was added before the starting of the experiments? How did the authors evaluate the influence of N excess in 2017 experiments?
Page 7, lines 178: In the legend of Figure 5 was reported two times “in onion bulbs” should be removed.
Page 8, Figure 7: please, indicate what the two graphs (a, b) refer to;
Page 9, lines 265-267: as the authors stated, the environmental conditions and plants genotype affected onions growth, how could they state that the observed differences depended on treatments rather than on other variables? Why didn’t authors evaluate the option of conducting their experiments inside a greenhouse with more stable and controlled environmental parameters (light, irrigation, N/P soil content, temperature)? Regarding the differences observed between the two cultivars, did authors performed an analysis, or are aware of the typical chlorophyll a, chlorophyll b, crude fibre, antioxidants activity and zinc content of the two onion varieties? Could authors report the conditions under which controls were cultivated? Most importantly, why didn't authors considered the opportunity of testing a new experimental blend as fertilizer instead of evaluating the effect of commercial products? Please, point out the innovativeness of your research.
Yogita & Ram 2012. Effect of chemical and bio-fertilizers on quality of onion. HortFlora Research Spectrum Vol.1 No.4 pp.367-370 ref.7
Renuka et al., 2018 https://doi.org/10.1016/j.biotechadv.2018.04.004
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors took the reviewer’s comments on board and improved the manuscript “Biofertilizers enhance quality of onion”.
Taking into account the relevance of the topic focused on this manuscript, I think that it can be considered for publication.
