Cultivation Substrate Composition Influences Morphology, Volatilome and Essential Oil of Lavandula Angustifolia Mill.

Round  1

Reviewer 1 Report

This work was aimed to evaluate the effects of different growth substrates on three Lavandula angustifolia populations; since two substrates over three contain 30% demolition aggregates, one of the biggest points of interest relies on the study about feasibility to horticultural use of demolition aggregates. Indeed, the possibility to use such material as a growth substrate has strong aspects of novelty, since, as far, they have been mostly tried for urban planning (green roofs and similar). The work is new and original, language is plain and understandable, English form is correct. The experiment was properly planned and managed, and conclusions are – rather always- adequately supported by data. I only have some minor remarks, that I report in the following lines:

-          Page 2, line 56: check the opportunity to substitute “flowering stage” with “development stage”.

-          Page 3, table 1, line “Cr”, I wonder how the P:C substrate (70% peat, 30% compost) can have such a low Cr amount (37,2), when its constituents have a 10-fold content (137,7 and 135,8); a thorough check of the table would be convenient.

-          Page 3, figure 1: the graphical representation of T and solar radiation does not add any relevant information to the discussion, and in my opinion could be removed. Only few details inside the text will be sufficient.

-          lines 161-162: the statement that the addition of A causes a lack of available P is basically incorrect, since both P:A and P:C:A deal with the same A content. Probably, under this respect, the absence of C has a greater influence than the addition of A.

-          There is something unclear in the graph in fig. 2 (“blooming trend…”); usually, these representations are cumulative, i.e. they report the sum of flowering % in time, indicating when plants arrived at 100% flowering (or about). In your graph, the highest point is that of P:C at week 24 (about 37%); that’s ok, but what about the following weeks? A cumulative graph would give a better representation of flowering in time.

-          data interpretation (lines 146-178): it seems to me that none of the examined substrate characteristics can be claimed responsible for the differences in growth and development of Lavender plants, and despite the Authors’ efforts, the organization of the experiment does not allow any conclusion about it. The higher nutrients content of the P:C treatment could probably explain its “better performance”, but it should be noticed that, actually, such performance is better only in terms of plants survival and flower yield. Indeed, plants in the P:C treatment are shorter and smaller, that means that they were surely not in better conditions. Probably there are too many differences among substrates (among these, their hydraulic characteristics, that probably could explain some differences in plants survival) and this does not allow an univocal response. E.g., line 164, why the P:A low flower production should be due to the low level of P, and not, for example, to the low levels of K, or Mg?. Hence, I do suggest to describe the variations observed in the treatments, without attempting explanations that are not supported by data.

Author Response

R1
Comments and Suggestions for Authors

This work was aimed to evaluate the effects of different growth substrates on three Lavandula angustifolia populations; since two substrates over three contain 30% demolition aggregates, one of the biggest points of interest relies on the study about feasibility to horticultural use of demolition aggregates. Indeed, the possibility to use such material as a growth substrate has strong aspects of novelty, since, as far, they have been mostly tried for urban planning (green roofs and similar). The work is new and original, language is plain and understandable, English form is correct. The experiment was properly planned and managed, and conclusions are – rather always- adequately supported by data. I only have some minor remarks, that I report in the following lines:

-  Page 2, line 56: check the opportunity to substitute “flowering stage” with “development stage”.

AUTHORS: done

- Page 3, table 1, line “Cr”, I wonder how the P:C substrate (70% peat, 30% compost) can have such a low Cr amount (37,2), when its constituents have a 10-fold content (137,7 and 135,8); a thorough check of the table would be convenient.

 AUTHORS: checked, it is a typing error. The correct number is 137.2

- Page 3, figure 1: the graphical representation of T and solar radiation does not add any relevant information to the discussion, and in my opinion could be removed. Only few details inside the text will be sufficient.

AUTHORS: figure 1 has been removed as suggested.

- lines 161-162: the statement that the addition of A causes a lack of available P is basically incorrect, since both P:A and P:C:A deal with the same A content. Probably, under this respect, the absence of C has a greater influence than the addition of A.

AUTHORS: this sentence was deleted, modifying the text according to R1 last suggestion.

- There is something unclear in the graph in fig. 2 (“blooming trend…”); usually, these representations are cumulative, i.e. they report the sum of flowering % in time, indicating when plants arrived at 100% flowering (or about). In your graph, the highest point is that of P:C at week 24 (about 37%); that’s ok, but what about the following weeks? A cumulative graph would give a better representation of flowering in time.

AUTHORS: the figure of the blooming trend has been modified accordingly, using a cumulative representation.

- data interpretation (lines 146-178): it seems to me that none of the examined substrate characteristics can be claimed responsible for the differences in growth and development of Lavender plants, and despite the Authors’ efforts, the organization of the experiment does not allow any conclusion about it. The higher nutrients content of the P:C treatment could probably explain its “better performance”, but it should be noticed that, actually, such performance is better only in terms of plants survival and flower yield. Indeed, plants in the P:C treatment are shorter and smaller, that means that they were surely not in better conditions. Probably there are too many differences among substrates (among these, their hydraulic characteristics, that probably could explain some differences in plants survival) and this does not allow an univocal response. E.g., line 164, why the P:A low flower production should be due to the low level of P, and not, for example, to the low levels of K, or Mg?. Hence, I do suggest to describe the variations observed in the treatments, without attempting explanations that are not supported by data.

AUTHORS: the text has been modified accordingly, avoiding explanations not clearly supported by data.

Reviewer 2 Report

This paper is interesting and well written in general. The results indicated that 30% green compost and/or 30% demolition aggregates can be used as components of substrates. However, there are some confusions to be checked the original data. And some points to be considered for revision.

1.       Abstract: reduce the introduction part, increase the specific results and concise conclusion.

2.       Line 77 to Line 82 from “Demolition aggregates------” and Table 1 should be moved to “Results” part.

3.       Table 1, It is strange that the C tot of P:C mix is much higher than the P or C alone. Where does it come from? as well as C/N. And Cr, Cu, Ni are much lower than the single component after you mix them? And why N tot in PCA is lower than that of PC and PA? Data of pH and C/N also need SE.

4.       Line 172-173, Cu is an essential micronutrient for plant growth. Ni is proved to be beneficial for plant growth. They will not reduce plant growth unless the concentrations are over the limits and unbalanced. It is necessary to compare if they are exceeded the limits in soil. It could be better if the contents in plant tissue are measured. And the pH of the substrates varied from 5.1 to 8.2, the high pH of 8.2 will reduce the availability of most micronutrients in the substrates, it could be better if the authors can present the contents of nutrients in the plant tissue and give a deep discussion on it.  

5.       Line 206-207. Delete the first sentence.

6.       Line 240-241, but in Table 5, the yield of EO in Sus with P:C:A is “vl”, very low. So, not all EO yields in PA and PCA were “higher”. And carefully check the data, the yield of EO had very high standard error or standard deviation in table 5. Such as in Sus of P:C, the number is 0.4±0.4, in Tan of P:C, it is 0.2±0.22, the SE is even larger than the yield itself; as well as in Stu of P:C:A, 0.2±0.24. There are so great variation in these data. Do they really have significant difference statistically by comparing the means?

7.       Line 248-249, In order to compare the total amounts of Eos yield, I suggest you calculate the EO yield in table 5 with W/W (it is better to say “concentration or contents” instead of “yield” in table 5) by the total weight of flowers in table 2 to get the total yield.

8.       Line 312-313, based on point 6, after calculate and compare the total yield, than give a reliable conclusion.

For more detailed comments, please see the corrected manuscript.

Comments for author File: Comments.pdf

Author Response

R2

Comments and Suggestions for Authors

This paper is interesting and well written in general. The results indicated that 30% green compost and/or 30% demolition aggregates can be used as components of substrates. However, there are some confusions to be checked the original data. And some points to be considered for revision.

1. Abstract: reduce the introduction part, increase the specific results and concise conclusion.

AUTHORS: done

2. Line 77 to Line 82 from “Demolition aggregates------” and Table 1 should be moved to “Results” part.

AUTHORS: we would prefer not to move table 1 and its description to Results part since data do not derive from an experimentation but are a description of the substrates used.

3. Table 1, It is strange that the C tot of P:C mix is much higher than the P or C alone. Where does it come from? as well as C/N. And Cr, Cu, Ni are much lower than the single component after you mix them? And why N tot in PCA is lower than that of PC and PA? Data of pH and C/N also need SE.

AUTHORS: we checked the data and verified the analyses of the substrates and mixtures. Information in table 1 are correct, thus we can hypothesize that the two locally sourced materials (green compost and demolition aggregates) used in the experiment did not have homogeneous traits. This is often a remarkable issue in the attempt to find suitable materials alternative to peat. SE was added for pH and C/N.   

4. Line 172-173, Cu is an essential micronutrient for plant growth. Ni is proved to be beneficial for plant growth. They will not reduce plant growth unless the concentrations are over the limits and unbalanced. It is necessary to compare if they are exceeded the limits in soil. It could be better if the contents in plant tissue are measured. And the pH of the substrates varied from 5.1 to 8.2, the high pH of 8.2 will reduce the availability of most micronutrients in the substrates, it could be better if the authors can present the contents of nutrients in the plant tissue and give a deep discussion on it. 

AUTHORS: the manufacturer of demolition aggregates raised the issue that some metals could have been very high in the material, thus the Cu, Cr, and Ni analysis was planned to verify if their amount could have been phytotoxic. Since lavender plants were not addressed to food uses we did not plan the analysis of these metals in plant tissues. Unfortunately, the plant material is not available anymore for further analyses. In the text, the accepted limits of heavy metals in soil according to Italian legislation has been added, highlighting their very high concentration in the P:C:A substrate. 

5. Line 206-207. Delete the first sentence.

AUTHORS: done

6. Line 240-241, but in Table 5, the yield of EO in Sus with P:C:A is “vl”, very low. So, not all EO yields in PA and PCA were “higher”. And carefully check the data, the yield of EO had very high standard error or standard deviation in table 5. Such as in Sus of P:C, the number is 0.4±0.4, in Tan of P:C, it is 0.2±0.22, the SE is even larger than the yield itself; as well as in Stu of P:C:A, 0.2±0.24. There are so great variation in these data. Do they really have significant difference statistically by comparing the means?

AUTHORS: done. The SD has been revised and corrected according the referee suggestion. In this why there is not a statistically significant variation.

7. Line 248-249, In order to compare the total amounts of Eos yield, I suggest you calculate the EO yield in table 5 with W/W (it is better to say “concentration or contents” instead of “yield” in table 5) by the total weight of flowers in table 2 to get the total yield.

AUTHORS: done

EO yield means the EO amount obtained from a determined quantity in weight of plant material by hydrodistillation. It is not a concentration and even content.

The hydrodistilled plant material consisted of  all lavender aerial parts and not only flowers

8. Line 312-313, based on point 6, after calculate and compare the total yield, than give a reliable conclusion.

AUTHORS: done. See point 6.

Reviewer 3 Report

Dear authors:

I have revised carefully your paper agronomy-548832 entitlted “Cultivation substrate composition influences morphology, volatilome and essential oil of Lavandula angustifolia Mill.” and I think it is good enough to be published in this journal. However, I think few little modifications should be done before.

Abstract and 2.1 Soilless cultivation: Please do not leave space between the number and the percentage “ratios: 70:30% v/v, 21 P:C; 70:30% v/v, P:A; and 40:30:30% v/v, P:C:A.”. “within 20km from the nursery”.

With respect to the survived plants, could you explain it that should after the plant were plotted or before. I mean, may be each locality have a different survival percentage during Cutting propagation or may be the subtract also affect to the it?

Results and discussion: Please leave out the author of the species after the first time you mention them “For example, Thymus vulgaris L. was positively influenced by high nutrient concentrations in the growing media [41], and there is evidence that phosphorus (30-70 mg L^-1) and potassium (>300 mg L^-1) improves the plant growth parameters of lavenders [29], as did potassium in Rosmarinus officinalis L. [46]. Other author, however, did not record significant effects by potassium modulation on Origanum dictamnus L. growth [47].”

Please correct the LRI of compounds that share it (993, 1142, 1170, 1188, 1230 and 1660) in the different tables.

The “o” and “p” of the next compounds should be on italic: o-cymene; p-cymene; cis-p-menth-2-en-1-ol; p-cymen-8-ol and cis-p-mentha-1(7),8-dien-2-ol (different tables).

References: I think you should include references of Usano-Alemany et al. (2014 a, b and c and 2016 ) that have been worked with the same species.

Best wishes.

Author Response

R3

Comments and Suggestions for Authors

Dear authors: 

I have revised carefully your paper agronomy-548832 entitlted “Cultivation substrate composition influences morphology, volatilome and essential oil of Lavandula angustifolia Mill.” and I think it is good enough to be published in this journal. However, I think few little modifications should be done before. 

1.Abstract and 2.1 Soilless cultivation: Please do not leave space between the number and the percentage “ratios: 70:30% v/v, 21 P:C; 70:30% v/v, P:A; and 40:30:30% v/v, P:C:A.”. “within 20km from the nursery”.

AUTHORS: done

2.With respect to the survived plants, could you explain it that should after the plant were plotted or before. I mean, may be each locality have a different survival percentage during Cutting propagation or may be the subtract also affect to the it?

AUTHORS: in the “2. Materials and methods” has been specified that the survival rate was evaluated at the end of the trial, moreover the interaction of locality factor is described before table 2.

3. Results and discussion: Please leave out the author of the species after the first time you mention them “For example, Thymus vulgaris L. was positively influenced by high nutrient concentrations in the growing media [41], and there is evidence that phosphorus (30-70 mg L^-1) and potassium (>300 mg L^-1) improves the plant growth parameters of lavenders [29], as did potassium in Rosmarinus officinalis L. [46]. Other author, however, did not record significant effects by potassium modulation on Origanum dictamnus L. growth [47].”

AUTHORS: done

4. Please correct the LRI of compounds that share it (993, 1142, 1170, 1188, 1230 and 1660) in the different tables.

AUTHORS: done. We correct the LRI of Compounds in both tables.

5.The “o” and “p” of the next compounds should be on italic: o-cymene; p-cymene; cis-p-menth-2-en-1-ol; p-cymen-8-ol and cis-p-mentha-1(7),8-dien-2-ol (different tables).

AUTHORS: done. All “o” and “o” were corrected in the requested font.

6. References: I think you should include references of Usano-Alemany et al. (2014 a, b and c and 2016 ) that have been worked with the same species.

AUTHORS: done

Round  2

Reviewer 1 Report

I appreciate the Authors' efforts, and in my opinion the manuscript is ready for publication. I just noticed two typing mismatches - too small for listing them among "revisions" - , namely: 

Abstract, Line 22: correct EOs (capital letters)

Line 235: something occurred with the copy-and-paste function.