The Impact of CO2 Enrichment on Biomass, Carotenoids, Xanthophyll, and Mineral Content of Lettuce (Lactuca sativa L.)
Round 1
Reviewer 1 Report
The manuscript title “The Impact of CO2 Enrichment on Biomass, Carotenoids, Xanthophyll, and Mineral Content of Lettuce (Lactuca sativa L.)” has major concerns. This MS need significant changes and improvements. My detail comments for authors are as follows:
1- Give figure number to the chamber picture;, give name like Figure 1 (Line 143) than write its caption; and the next picture as Figure 2 (Line 218) and so on change the figure numbers accordingly.
2- Please explain the formula or standard used for anthocyanins determination. It is missing (Line: 200-201).
3- Write the ‘Rex’ and ‘Rouxai’ name in the figure (Line 218).
4- Keep sequences in the Figure numbering representation in the MS. You have mentioned figure 4 in line 242 and then jump to figure 6 in line 243. You have to mention or explain the figure 5 first than move to figure 6.
5- Where is Figure 6? In Line ‘243’ authors mentioned Figure 6 but it is not present in the MS.
6- Line 261-262 “Overall, lettuce biomass increased and violaxanthin decreased with increasing CO2 concentrations”. It seems to be a confusing sentence for readers, please remove or rewrite/split the sentence. Violaxanthin decreased significantly in ‘Rouxai’ only while in ‘Rex’ it is non-signifcant. Don’t mention the significant and non-significant results in one sentence, if you are willing to write together than you have to mention which is significant and which is non-significant.
7- As the figure 7 and 8 results are non-significant, so, I suggest authors to remove the figure 7 and 8 from the MS and place them in the supplementary files.
8- Improve the discussion section and also focus on the significant results. Also explain the varietal difference in the discussion section, the colored lettuce ‘Rouxai’ have significant difference in Violaxanthin whereas the non-colored lettuce ‘Rex’ have no significant difference.
Author Response
Thank you for reviewing the manuscript.
Please see attached document.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
General: The overall research design is clear and deals with detecting the response of lettuce on higher levels of CO2. The structure of the manuscript is suitable. Steps towards reduced energy levels are crucial in all levels of plant production so this study is promising. I believe that the manuscript may be published pending some minor corrections.
Title: Adequate
Keywords: Adequate but insert a comma between lettuce and Lactuca sativa
Abstract: Combines background information for the study, methodology and major results. The text is concise, well-written and easy to follow.
Introduction: Generous information on the importance of analyzing the effect of supplemental CO2 on greenhouse crops and particularly on lettuce production. Previous studies focused on evaluating the increase in yield, amino acids, chlorophyll, nitrogen, and phosphorus and the present study evaluated the effect of CO2 on some bioactive compounds. The aim is clearly stated. In L96 I believe there is a grammatical mistake: no information on the literature (correct to in the literature)
Materials and methods: Rewrite the sentence in L128-131, the conditions where plants were kept are not described correctly. I assume that acrylic chambers were places in walk.in growth chambers and not vice-versa as it reads in text. All morphological and chemical analyses were performed in detail and are repeatable.
Results: Clear and informative, the section need almost no editing. In L 249 change to singular (variety), in L256 eliminate was, in L260 ‘Rex’ and eliminate a surplus punctuation at the end of the sentence. In L272 start the sentence: ANOVA analysis showed, in L279 change to Shoot and leaf micronutrients concentration (in mg/kg) of ‘Rex’ and.
Discussion: The discussion is well supported by previous references and findings are discussed in a concise manner. Consider altering the sentence in L309-310 as it is not clear. The authors found no direct effect of increased CO2 on anthocyanin content and speculate that as these compounds are synthesized under higher light that further studies are needed to define if the positive impact of high levels of CO2 at lower light are indeed true for red-leaf lettuce. I think it is debatable and that the authors need to stress this fact in the discussion.
Conclusion: Summarizing and clear.
Author Response
Thank you for reviewing the manuscript. The other reviewer had additional points that were addressed as well. Specifics included in your feedback are noted in the attached document.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors made sufficient changes in the Manuscript.
