Adapting American Hop (Humulus lupulus L.) Varieties to Mediterranean Sustainable Agriculture: A Trellis Height Exploration

Round 1

Reviewer 1 Report

Warm dry climates with ample soil moisture is essential for highest production of hop plants. Here author evaluate the growth performance of "Cascade" and "Chinook" hop varieties on "V" trellis systems at different heights in Mediterranean climate and soil conditions. They found that low-trellis farming significantly improved the adaptive potential of hope. The manuscript is quite interesting however, the following issues need to address before considering the manuscript.

Author suggested to add the scientific name of American hop in title or at least in the abstract.

Author suggested to elaborate mechanistic discussion how low-trellis improved the adaptive response of hop plants in Mediterranean climate and soil conditions.

This study provides  only growth attributes data, author suggested to provide some biochemical attributes at least to unveil the involved mechanisms of adaptation.

Author Response

Authors’ replies to Reviewer 1

Warm dry climates with ample soil moisture is essential for highest production of hop plants. Here author evaluate the growth performance of "Cascade" and "Chinook" hop varieties on "V" trellis systems at different heights in Mediterranean climate and soil conditions. They found that low-trellis farming significantly improved the adaptive potential of hope. The manuscript is quite interesting however, the following issues need to address before considering the manuscript.

Author suggested to add the scientific name of American hop in title or at least in the abstract.

Reply: Thanks for this suggestion. We added the scientific name in the title.

Author suggested to elaborate mechanistic discussion how low-trellis improved the adaptive response of hop plants in Mediterranean climate and soil conditions. This study provides only growth attributes data, author suggested to provide some biochemical attributes at least to unveil the involved mechanisms of adaptation.

Reply: This study was intentionally meant to focus mostly on growth attributes data; thorough investigations on the mechanisms underlying hop cones yield will be addressed in future. However, some possible explanation for the good yield performance of low trellis system is suggested at lines 290-294.   

Reviewer 2 Report

The manuscript contains quite interesting results from a two-year study from one location with two hop varieties. The methodology needs to be supplemented with information on the number and timing of measurements, size of harvest plots, etc. I suggest the Authors to indicate the subject of future research.

Line 62, please include a drawing with the location of the study site.

Figure 1, please supplement with multi-year data

Table, 1 instead of organic matter content, please give organic carbon content, instead of P₂O₅ and K₂O – P and K content. Units are mg g^-1 soil. What methods were used to determine soil parameters? When were the samples taken? Is the pH determined in KCl or in H₂O?

Line 74, please give the characteristics of the two hop varieties

Table 2, please provide the chemical composition of the applied fertilisers and biostimulants

Line 121, please provide full details of the manufacturer of the statistical software

References, quite a small number of publications (only 27). Some of them are more than 10 years old and some are from the last many. These I suggest removing.

Author Response

Authors’ replies to Reviewer 2

The manuscript contains quite interesting results from a two-year study from one location with two hop varieties.

The methodology needs to be supplemented with information on the number and timing of measurements, size of harvest plots, etc. I suggest the Authors to indicate the subject of future research.

Reply: the M&M section was enlarged, including the requested information. The subject for future research was indicated in the “Conclusions” section (lines 301-305).

Line 62, please include a drawing with the location of the study site.

Reply: a Google Earth image was added, reporting the location of the study site and a close-up photo of the experimental hopyard.

Figure 1, please supplement with multi-year data

Reply: multi-year (30-y) data were added within each graph.

Table, 1 instead of organic matter content, please give organic carbon content, instead of P2O5 and K2O – P and K content. Units are mg g-1 soil. What methods were used to determine soil parameters? When were the samples taken? Is the pH determined in KCl or in H2O?

Reply: additional information was inserted in table 1, and measurement units were corrected.

Line 74, please give the characteristics of the two hop varieties

Reply: details on the two hop varieties chosen for the trial were inserted (see lines 84-89).

Table 2, please provide the chemical composition of the applied fertilisers and biostimulants

Reply: We provided more information in the M&M section concerning the biostimulants used in the trial (lines 103-110).

Line 121, please provide full details of the manufacturer of the statistical software

Reply: we inserted additional information concerning the statistical softwares adopted for the data analysis (lines 133; 144-146).

References, quite a small number of publications (only 27). Some of them are more than 10 years old and some are from the last many. These I suggest removing.

Reply: Limited research exists on this topic. Therefore, we have focused on relevant literature regarding hops farming and management in areas possibly similar to the Mediterranean ones, without taking into consideration the publication year. However, we removed some old reference.

Round 2

Reviewer 1 Report

Biochemical attributes like enzymatic activity or hormonal interaction study is essential for confirming the adaptation mechanisms.

Author Response

Reviewer 1: Biochemical attributes like enzymatic activity or hormonal interaction study is essential for confirming the adaptation mechanisms.

Reply: thank you for your observation, we totally agree. We inserted it in the “conclusion” section, as a lead for future research.