Variation in Yield, Berry Distribution and Chemical Attributes of Coffea arabica Beans among the Canopy Strata of Four Genotypes Cultivated under Contrasted Water Regimes

Round 1

Reviewer 1 Report

Comments for authors on horticulturae-2160508

 Title: Variation in Yield and Chemical Attributes of Coffee Beans 2 Over the Vertical Profile of Four Genotypes Cultivated Under 3 Two Water Regimes

 Factors studied: main effects of Genotype, irrigation, light (berry position along the plant height or canopy strata of the plant) and harvesting year (1^st and 2^nd harvest) and the interaction effects between genotype and irrigation regime or canopy stratum on light interception (distribution through canopy strata), leaf and branch areas per berry, number of berries per plant, vertical and radial distributions of berries, bean benefitted mass, dry mass performance, benefitted mass performance, berry and bean yields, and chemical compositions of beans for two harvest years.

 The research is excellent and the paper is well written. But the following issues require a due attention.  

 Title: can be improved based on the following information

 -       the title is not complete enough or it does not present enough the contents of the paper as the study examined a number of variables other than yield and chemical attributes of coffee

-       The phrase “Vertical profile” in the title is a confusing term. It should be substituted by an appropriate (clearer) one, like along the plant height or plant canopy strata. The same is required through the entire paper.  

 Abstract: can be improved based on the following information

 -       Line 18:…light impacts ‘in” Coffea arabica….see yellow highlighted letter (‘i’) on the word ‘in’.

-       Lines 19-20: are only berry yield and bean chemical traits studied in this study?

-       Lines 22-23: not clear

-       Line 25: what is a benefitted mass performance?

-       Lines 22-23: Was a correlation analysis between chemical composition and cup quality carried out in this study?

-       Line 35: what is a benefitted biomass?

-       Line 25: in……all genotypes) …see the relevance of the yellow highlighted bracket.

Introduction: must be improved based on the following information

-       In the introduction, there is no enough rationale of the study -  no information and literature review on how genotype, water deficit (irrigation), light (berry position along the plant height or plant canopy strata), harvest year and their interactions (especially the interactions between genotype and other factors considered in this study as indicated in the study objective) affect differently berry yield, bean chemical composition and other traits of arabica coffee considered in the study, but less relevant ones to show the nobility of this study; e.g., details on plant structure (lines 44-54), stage of flower development (lines 55-69) and fruit anatomy (lines 70-76). Moreover, information on water deficits in the study area that helps to visualize the impacts of supplemental irrigation vs. the area’s recurrent water deficit on studied variables (e.g., yield and bean chemical composition) is lacking here and also in Materials and Methods section, except that of the amount of irrigated water as supplemental irrigation in the latter. The consecutive paragraphs of the introduction are also not well conceptually connected to each other, as the result the flow of information towards the study objectives is not a good one

-       Line 71 and 73: Are exocarp and pericarp not the same term?

-       Line 73: what are benefited beans?

-       Lines 82-84: the information on Chemical composition of arabica coffee (Farah, 2012) needs to be checked

-       Line 91:….and 3) cultural management practices…..    or consider the term “:and” before the phrase ‘3) cultural management practices…..”

 Materials and Methods: can be improved by addressing the following issues

-       Section 2.1. What was the experimental design and plot size (number of coffee plants per plot) of the study?

-       Lines 119-120: Two Ethiopian wild accessions ('E027' and ‘E083’) were chosen because of their outstanding architectural characters shown in spring 2011. But, the coffee seedlings for this study were planted in 2010 (Line 115). This means the two genotypes were chosen for this study a year after this study’s coffee planting.   How could this be?

-       Lines 137-138: Is this amount and number of split NPK fertilizer per year applications only in the two harvest years or over the entire period from the year of planting to the 2nd harvest?

-       Lines 139-142: the phrase “considering 40 cm-thick-layers, starting from 20 cm of height (average height of coffee trunks)” in this statement is not clear.  What does a 40 cm-thick-layer and a 20 cm of height (average height of coffee trunks) means? Is it the thickness of the canopy of a given canopy layer and the average height of the trunks of the coffee plants in a plot, respectively? There is the same question (issue) (i.e., over the 40 cm-thick strata) in Lines 317 and 360-361?

-       Line 153: processing of what?

-       Lines 156-158: The last phrase in this statement (of ca. 40 cm high) needs either some modification or removal from the statement as it now shows that all the 4 strata had a 40 cm height from the ground.

-       Lines 178-179: The dry and benefitted bean mass performances were calculated as ratios of BM or DM to FM, respectively. Check this statement and see yellow highlighted terms.

-       Line 181: what are benefited material and air local?

-       Lines 181-182: Why harvest year was considered for bean chemical composition analysis? 

-       Line 198: What does the phrase….” with a plant as a unit” … indicated? Did this study have one plant as experimental unit or what?

-       Line 196-209 (Statistical analysis):  why didn’t you use harvest year as a replication rather than analyzing the data of the two harvests separately?

 Results

-       Lines 226-227:……. viewed by, view by difference among PPFD of reference and S2, in IRR and NI plants in 2012….cheeked the language of the highlighted section of  the statement.

-       Lines 225-228: How did you say this when Figure 2A (2012) does not consist of S3 and Figure 2B shows a higher PPFD  for S2 of NI plants than for S2 of IRR plants?

-       Lines 241-248: How the data of number of berries per plant was collected?  The data collection procedures used for this variable is not described in the Materials and Methods section.

-       Line 284: …. in IRR tan in NI plants…. see yellow highlighted word or ‘tan’.

-       Line 301 (Table 1), Line 320 (Table 2) and Line 345 (Table 3):  what does the hyphen (-) in row of Gen x Water indicate?

Discussion: Good

Conclusion:  improvement is required.  

-       Lines 541-558: It is just the description of the results.

Comments for author File: Comments.docx

Author Response

Thank you for your excellent revision. All responses are done in the attached file. If the corrected version is opening new questions and suggestions, we will have a pleasure to respond and to improve the MS.

Author Response File: Author Response.docx

Reviewer 2 Report

Thanks for the opportunity to review this research. The manuscript entitled „Variation in Yield and Chemical Attributes of Coffee Beans Over the Vertical Profile of Four Genotypes Cultivated Under Two Water Regimes” have described the drought and light impacts in Coffea arabica L. yield and bean quality Berry yield and bean chemical traits were studied over the plant vertical profile of four genotypes (Iapar 59, Catuaí 99 and two Ethiopian wild accessions, ‘E083’ and ‘E027’) cultivated with and without additional irrigation, in two initial harvest years. The subject of the manuscript is topical, but I recommend the publishing of the paper after the necessary corrections.

1. The abstract should be beginning with a sentence about the background of concept and the aims as well as novelty of study should be mentions. Please improve.

2. Introduction: Check and format the citations in the whole manuscript. Also, Appropriate references must be provided to explained the background, what is already done and why this study carried out. Hypothesis statement is missing in the introduction section.

3. Material and methods: The used methods are accurate.

4. Results and discussion: The results are clearly presented. General remark to the discussion: In my opinion, the discussion provided by authors is difficult to follow and verify due missing critical details.

I have only one recommendation to authors: please improve the conclusion of the manuscript and check the text for technical errors.

Author Response

Thank you for your excellent revision. All responses are done in the attached file. If the corrected version is opening new questions and suggestions, we will have a pleasure to respond and to improve the MS.

Author Response File: Author Response.docx

Reviewer 3 Report

Variation in Yield and Chemical Attributes of Coffee Beans Over the Vertical Profile of Four Genotypes Cultivated Under Two Water Regimes

Overview

The manuscript represents a detailed and in-depth experimental work investigating yield and chemical attributes over the vertical plant profile of four genotypes, under irrigated and non-irrigated regimes. The introduction is lengthy but informative and incorporates two useful ‘mini’ reviews for coffee crop plant morphology, and chemical (metabolite)/sensory diversity, based on environment and genome. The study itself has considerable merit, with valuable information on how to conduct certain aspects of pre-breeding work, and may have useful implications for Arabica breeding.

              Generally, the study is easy to comprehend, although I found Figure 6 rather difficult to interpret. Some sections are tightly written (with perhaps too much information). It may have been better to separate the experiments/outcomes into two separate papers, e.g., a separate one on the vertical profile, which would enable the authors more opportunity for explanation to readers who are not experts in this field. That’s just a suggestion.

              The use of English is of a reasonably high standard, but further careful editing is required at some point to bring it up to final publication standard.

              Below are some general and specific comments. I believe that each of these comments need to be addressed carefully.

General Comments

1. Ideally, the soil moisture, and/or soil water potential should have been measured for irrigated (IRR) vs. non-irrigated (NI) plots, otherwise it is impossible to measure the real influence of the water treatment regimes. Particularly given point 2, below.

2. Rainfall should have been measured for the non-irrigated (NI) plots, otherwise there is no means of evaluating the influence of soil water availability and their relationship to the variables measured, particularly given the large variation between 2012 and 2013.

3. It is essential that the exact number of plants used in the experimentation is given (see below).

4. Ideally MLVTs would have been used to back up these results, and the breeding recommendations for specific genotypes, as you only have one location. MLVTs for Arabica show considerable variation across different climates. Only one variable is being modified in these experiments, soil water availability, although soil water metrics are unknown (not recorded).

5. 1000 kg of NPK/per ha is a considerable amount of fertilizer. What would have been the variation in genotype/cultivar performance without this. Should it be stated that the selection of EO83 for breeding work should be caveated as a good performing genotype under high input conditions?

6. Is two years an a sufficient time-frame for drawing firm conclusions on genotype selection.

Specific comments

Abstract

Line 20

“…over the plant vertical profile of four genotypes…”

It may be better to say vertical profile of the plant, or some other means of providing an idea of its meaning to the reader.

Line 22

“The berry distribution reached lower height in not irrigated…”

Please rewrite so that the meaning is clear.

Line 73

“…pectic adhesive layer and parchment together with bean silverskin are removed from the coffee beans [15]…”

A large proportion of the silverskin is often removed upon roasting, depending on the processing involved (e.g. polishing).

Line 118

2. Materials and Methods

“…(planting density of 8000 plants ha-1 ),…”

It is essential that the exact number of plants used (in all parts of the experimentation) is given. It is not clear (or stated) how many plants were used in the experiments. Please state the exact number of plants used for each treatment.

Line 127

“The soil was dusky-red dystrophic latosol. Climate is subtropical, Köpen-Geiger climate type Cfa, with average annual precipitation of about 1585 mm, ranging from 55 mm 128 in the driest month (August) to 245 mm in the wettest one (January).”

The exact precipitation should have been measure (daily if possible) for the NI plots. Please update ms. accordingly.

Line 241

“Total berry number per plant harvested in 2012 greatly differed among the four…”

How many plants were measured/recorded for this part of the experiment. Please update ms. accordingly.

Line 302

“In the 2nd harvest year (2013), great increments in berry FM, DM and bean BM were obtained under IRR compared to NI soil water availability, being much higher for two Ethiopia accessions than for two cultivars (Table 1).”

This is likely to be influenced by the rainfall and available soil moisture for each year. Please update ms. accordingly.

Conclusion

Should it be stated that whilst yield is reasonably consistent, other metrics are highly variable over the two years. Please update ms. accordingly.

Line 543

What are the conclusions regarding IRR vs. NI for metabolites/compounds?

Line 545

“Additionally, the yield and chemical composition were strongly impacted by light availability over the vertical profile, interlinked to genotype and water management, proving our hypothesis.”

I think it would be useful to restate the hypothesis in this part.

Line 558

“Based on berry vertical and radial space occupation and bean quality, the Ethiopian wild accession ‘E083’ must be considered in the future breeding programs”

Surely, also because it’s high yielding under IRR and NI conditions? Please update ms. accordingly.

Author Response

Thank you for your excellent revision. All responses are done in the attached file. If the corrected version is opening new questions and suggestions, we will have a pleasure to respond and to improve the MS.

Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript contains quite interesting results of two years of research. Unfortunately, they are already 10 years old, because they come from 2012-2013. For this reason, the advisability of their publication is questionable.

Comments

Line 116, please post a figure with the location of the research site.

Line 127, please give the characteristics of the soil conditions.

Line 128, please provide a more detailed description of the weather conditions during the study period.

Line 197, please provide full details of the statistical software manufacturer.

References, please remove publications older than 10 years.

Author Response

Thank you for your excellent revision. All responses are done in the attached file. If the corrected version is opening new questions and suggestions, we will have a pleasure to respond and to improve the MS.

Author Response File: Author Response.docx