Response of Oil Production and Quality to Hedgerow Design in Super-High-Density Olive cv. Arbequina Orchards

Round 1

Reviewer 1 Report

Aim of the researches carried out and which results are object of the paper was to study the variation of  phenological,  quantitative and qualitative traits of olive fruits  and its product (oliv oil)  as related to the  environmental conditions  that can be detected in hedgerow planting systems, belonging to the category of Super High Density (SHD) orchards.

Different microclimates, discriminated on the basis of a light interception model and fruit temperatures were obtained  varying the tree planting distances between rows (5, 3.75 and 2.5 m), rows orientation  (N-S, E-W) and canopy position along the  vertical (height) profile of the canopy. Drupes samples were taken harvesting separately the fruit in 5 different canopy layers. The study has been carried out on trees of "Arbequina" 

 

The study, although not original and innovative,  is scientifically sound, well presented and confirms the importance of fruit canopy position on phenology and quality traits (check the large literature on this subject that has been published for temperate zones fruit crop) .

Before publishing Authors are required to address the following comments 

Second page, I suggest to restrict your study sampling fruit at the eight layers 0.4-0.8/1.6-2.0 m because  

 

line 103: above 2.0 it is hard to have the same porosity (20%) you have in the other layers along the vertical profile of the canopy  

line 108:  Authors state detected fruits in the height layer 0.0-0.4m. Usually in the hedgerow planting systems this layer doesn't exist since the need to control weeds (by tilling, herbicide) along the rows and because the overhead machines are not able to collect fruits bore on canopy lower than 60 cm.

Deleting the data relative to the two above layers could significantly change slop and R2 of regressions (Fig.1) thus the statistical significance of the data correlations. I recommend to check it.

Conclusions section: in the  paper you never discuss the effect on olive oil quality, particularly polyphenols,  of tree water status although changing plantation density and row orientation, having large differences in the Leaf Area Index, thus in the seasonal variation of the amount of light quantity and quality (i.e. Red/IR) intercepted, can effect tree water realtions (SWP), conductance and orchard transpiration fluxes.     

 

Author Response

Reviewer 1

We would like to specially thank the reviewer for observations and contributions made to improve the quality of manuscript.

 

Line 67: You can add this reference to the text because is about SHD orchards from Spain and with three different varieties. Characterization of Olive Oils from Superintensive Crops with Different Ripening Degree, Irrigation Management, and Cultivar: (Arbequina, Koroneiki, and Arbosana). Eur. J. Lipid Sci. Technol., 2019, 121: 1800360.

A 1: Thank you, the reference Vidal et al., 2019 was added in introduction of revised ms.

 

Line 79: There is two spaces.

Line 83: There is two spaces.

A2-3: The spaces were revised and corrected in revised ms.

 

Line 114: What does mean “ca.”?

A4. It means approximately. It is now appropriately italicized in the text

 

Line 121: What quantity of sample was processed by Abencor?

A5. This information was included in the revised ms.

 

Line 188 195: Although everyone understands the statistical parameters, you should put what does mean the letters a, ab, b, and ns.

A6. Explanation was added to legend of Table 1.

 

Line 260 262: What does mean 347 % on the maturity index? Why it is so high?

A7. Unfortunately, the maturity index was wrongly presented. The correct value 0.35 is now shown in the new version of the manuscript.

 

Line: º of ºC is not well write. You should put as the line 375.

A8. Changes made for consistency in lines 373–376

Reviewer 2 Report

In general, the text is good, the methodology is clear, and theresults and discussion is very good. Only some suggestions and question are required.

Line 67: You can add this reference to the text because is about SHD orchards from Spain and with three different varieties. Characterization of Olive Oils from Superintensive Crops with Different Ripening Degree, Irrigation Management, and Cultivar: (Arbequina, Koroneiki, and Arbosana). Eur. J. Lipid Sci. Technol., 2019, 121: 1800360.

Line 79: There is two spaces.

Line 83: There is two spaces.

line 114: What does mean “ca.”?

Line 121: What quantity of sample was processed by Abencor?

line 188: Although everyone understands the statistical parameters, you should put what does mean the letters a, ab, b, and ns.

Line 260: What does mean 347 % on the maturity index? Why it is so high?

Line 371: º of ºC is not well write. You should put as the line 375.

Author Response

Reviewer 2

We would like to specially thank the reviewer for observations and contributions made to improve the quality of manuscript.

 

Before publishing Authors are required to address the following comments 

Second page I suggest to restrict your study sampling fruit at the eight layers 0.4-0.8/1.6-2.0 m because.

 

line 103: above 2.0 it is hard to have the same porosity (20%) you have in the other layers along the vertical profile of the canopy  

 

line 108:  Authors state detected fruits in the height layer 0.0-0.4m. Usually in the hedgerow planting systems this layer doesn't exist since the need to control weeds (by tilling, herbicide) along the rows and because the overhead machines are not able to collect fruits bore on canopy lower than 60 cm.

 

Deleting the data relative to the two above layers could significantly change slop and R2 of regressions (Fig.1) thus the statistical significance of the data correlations. I recommend to check it.

 

The following answer combines responses to the three issues raised above. The referee detected and was misled by an incomplete description of methodology that has been corrected (line 111) Apologies for that!. The adjusted text explains that the canopy layers referred to here are measured from the base of the 2 m canopy at 0.5 m aboveground.  Tree height was consequently maintained by topping at 2.5 m (line 104).  The top layer did include regrowth from topping and therefore of more variable porosity, but not always less that those below. We prefer to maintain that layer in the analysis because, in that way, we include the layer exposed to the greatest irradiance.

 

In addition, In Fig 1 data from top positions showed similar trend to lower positions. However, in some fatty acid, data from bottom positions showed different pattern (within circles) and were not included in correlations.

Conclusions section: in the paper you never discuss the effect on olive oil quality, particularly polyphenols, of tree water status although changing plantation density and row orientation, having large differences in the Leaf Area Index, thus in the seasonal variation of the amount of light quantity and quality (i.e. Red/IR) intercepted, can effect tree water relations (SWP), conductance and orchard transpiration fluxes.

This is an important issue that was discussed when the experiment was established. Irrigation information is now included in the ms.  Also, we have added some comments about light quality influence on olive oil quality in revised discussion. Stem water potential was evaluated and included in doctoral thesis by Trentacoste (2015) from which this paper is derived, but given the irrigation applied no differences between orchard orientations was found.

Reviewer 3 Report

The present work provides relevant information on the impact of orchard design factors (row spacing and orientation) on olive oil yield and composition. The manuscript is well-organized, and concise, and it fits within the scope of the journal. I did not find any major issue to raise apart from several minor comments that I list below, so I believe that the manuscript can be published after going through minor revisions.  

- Line 34. The “?” is not required

- Line 87. Among the oil components the phenolic compounds are known to be extremely sensitive to water availability during the fruit growth period. In general, the concentration of phenolic compounds in VOO decreases as water availability in the soil increases (e.g., Caruso et al, 2014, https://doi.org/10.1016/j.agwat.2013.12.003). As a result, I missed some information on the irrigation amounts and distribution applied in the different orchards under study. Was the same irrigation amount applied to all orchards? Did the orchards with higher leaf area index (lower row spacing) received more irrigation (otherwise differences in water status might arise among orchards)?    

- Line 179. “The circle” must be “the circles” as there are many of them

- Line 184. “from 5th to 6th year after planting”. I think it would be better to identify the years (i.e. 2012 and 2013) rather than the age of trees for the sake of clarity.

- Line 207. how was the date of pit hardening determined / assumed? The section of Materials and Methods do not comment on this issue.

- Lines 224 and 228. Units for 18.3, 17.6 and 12.4 are not show. Add “%”. In these lines (but also throughout the whole manuscript) superscripts must be used when indicating the units.

- Lines 259-261. At first I associated "ranges in percentage" as average concentrations at the indicated PAR level (5 mol/m2) or else as an indication of the dispersion of data at such PAR, but in either case the reported values do not make sense. I guess that some readers may be confused by this as I was, so please try to be more specific and describe how these values were calculated.

- Line 332. “measure” should be “measured”

- Line 403. Better use “hedgerows” instead of “rows” here, I guess

- Line 417-419. “Hedgerow design […] less evident influence on fruit temperature 418 in cv. Arbequina SHD orchards”. This result was somewhat expected for me. Olive canopies are tightly coupled to the atmosphere (e.g. Villalobos et al., 2013, http://dx.doi.org/10.1016/j.agrformet.2012.11.010), so leaves or fruits should follow closely air temperature fluctuations. Significant differences between the studied orchards are hence unlikely. This agrometeorological digression may be added somewhere in the discussion.

- Figure 1. The X scale for oleic acid in the N-S orientation panels is different from the one used for the E-W orientation panels. I suggest using the same scale. The same goes for linoleic acid panels.

- Figure 2. It is unclear whether the ANOVA is performed for comparing the row spacing treatments alone or both “row spacings” x “orchard orientation”

 

A job well done, congrats to the authors!

Author Response

Reviewer 3

We would like to specially thank the reviewer for observations and contributions made to improve the quality of manuscript.

 

The present work provides relevant information on the impact of orchard design factors (row spacing and orientation) on olive oil yield and composition. The manuscript is well-organized, and concise, and it fits within the scope of the journal. I did not find any major issue to raise apart from several minor comments that I list below, so I believe that the manuscript can be published after going through minor revisions.  

 

- Line 34. The “?” is not required

A1. The symbol “?” was already removed

 

- Line 87. Among the oil components the phenolic compounds are known to be extremely sensitive to water availability during the fruit growth period. In general, the concentration of phenolic compounds in VOO decreases as water availability in the soil increases (e.g., Caruso et al, 2014, https://doi.org/10.1016/j.agwat.2013.12.003). As a result, I missed some information on the irrigation amounts and distribution applied in the different orchards under study. Was the same irrigation amount applied to all orchards? Did the orchards with higher leaf area index (lower row spacing) received more irrigation (otherwise differences in water status might arise among orchards)?   

A2. Attentive to these useful observations, we have added more details in materials and methods and some comments in the discussion in revised manuscript.

 

- Line 179. “The circle” must be “the circles” as there are many of them.

A3. Thank you, this was corrected in revised ms.

 

- Line 184 189. “from 5th to 6th year after planting”. I think it would be better to identify the years (i.e. 2012 and 2013) rather than the age of trees for the sake of clarity.

A4. Accepted and adjusted.

 

- Line 207. how was the date of pit hardening determined / assumed? The section of Materials and Methods do not comment on this issue.

A5. In revised manuscript we have added more details in materials and methods

 

- Lines 232–234 224 and 228. Units for 18.3, 17.6 and 12.4 are not show. Add “%”. In these lines (but also throughout the whole manuscript) superscripts must be used when indicating the units.

A6. Thanks for the suggestion. After careful discussion we believe that for two or more continuous numbers with same units, adding units to all numbers seems redundant.

 

- Lines 259-261. At first I associated "ranges in percentage" as average concentrations at the indicated PAR level (5 mol/m2) or else as an indication of the dispersion of data at such PAR, but in either case the reported values do not make sense. I guess that some readers may be confused by this as I was, so please try to be more specific and describe how these values were calculated.

A7. Ok, we have improved the sentence for a simpler, more complete interpretation.

 

- Line 340 332. “measure” should be “measured”.

A8. This was corrected in revised ms.

 

- Line 403. Better use “hedgerows” instead of “rows” here, I guess.  OK corrected

A9. Accepted and adjusted.

 

- Line 417-419. “Hedgerow design […] less evident influence on fruit temperature 418 in cv. Arbequina SHD orchards”. This result was somewhat expected for me. Olive canopies are tightly coupled to the atmosphere (e.g. Villalobos et al., 2013, http://dx.doi.org/10.1016/j.agrformet.2012.11.010), so leaves or fruits should follow closely air temperature fluctuations. Significant differences between the studied orchards are hence unlikely. This agrometeorological digression may be added somewhere in the discussion.

A10. This is an interesting point, and some comments have been added in the Discussion of the revised ms.

 

 

- Figure 1. The X scale for oleic acid in the N-S orientation panels is different from the one used for the E-W orientation panels. I suggest using the same scale. The same goes for linoleic acid panels.

A11. Thanks for the observation. This was corrected in revised ms.

 

- Figure 2. It is unclear whether the ANOVA is performed for comparing the row spacing treatments alone or both “row spacings” x “orchard orientation”

A12. NS and EW hedgerows orientation were independently subjected to ANOVA. It was added in revised Figure 2.

 

 

Round 2

Reviewer 1 Report

the manuscript has been sufficiently improved