Risk of Extreme Early Frosts in Almond

Round 1

Reviewer 1 Report

The research is interesting and has a contribution to fruit growing. 

The conclusion is not well written. See document

Rewrite the conclusion

Comments for author File: Comments.pdf

Author Response

Independent Review Report, Reviewer 1
EVALUATION

The research is interesting and has a contribution to fruit growing. The conclusion is not well written. See document. Rewrite the conclusion.

Reviewer 1. Scientific names should be italicized or underlined.

Authors´ answer: Thanks for this comment, we have italicized all scientific names.

Reviewer 1. The conclusión must respond to the stated objective. Was it fulfilled or not?

Authors´ answer: The conclusion has been revised and we have answer the state question of: which effects did the early frost produced in the different cultivars? (Lines 173-177).

Reviewer 1. Recommendation or conclusion.

Authors´ answer: Thanks for this comment, we have added a final recommendation about how to avoid the damage caused by early frost (lines 177-179).

Author Response File: Author Response.docx

Reviewer 2 Report

In the manuscript there are several questions that I prefered remind in detail. Please the authors consider the comments in the pdf file.

Comments for author File: Comments.pdf

Author Response

Independent Review Report, Reviewer 2
EVALUATION

In the manuscript there are several questions that I prefered remind in detail. Please the authors consider the comments in the pdf file.

Reviewer 2. The authors in this paper will dissert on early or late frosts? I suggest to clear this sentence because is deceptive

Authors´ answer: Thank you for this comment, in almond the most important factor for determining the suitability of a certain cultivar in a particular area is the risk of frost. The most common frost in Spain are late frost that take place during the end of March or the beginning of April. In this sentence we wanted to point that late frost are the most common risk in almond, but there are also other threats such as ealy frost.

Reviewer 2. This sentence is not clear. The endodormacy depends by the structures inside the bud and not on the external conditions. However, the onset of dormancy occurs when the external signals (such as a minor photoperiod)that influences the biochemical mechanisms (such as a major production of abscissic acid causing leaf fall). According to some authors, the winter dormancy induction is associated with leaf fall. I suggested  to consider the following article Fadón, E., Fernandez, E., Behn, H., Luedeling, E., 2020. A Conceptual Framework for Winter Dormancy in Deciduous Trees. Agronomy 10, 241. https://doi.org/10.3390/agronomy10020241

Authors´ answer: We are grateful for this comment, we have change the sentence and now it specifies that chill accumulation is the main factor to take into consideration in the development of endodormancy and in its release. In addition, we have cite the paper that you suggested (lines 37 and 38).

Reviewer 2. Please consider the reference

Authors´ answer: Thanks, we have added a reference about the hours below 7.2 °C model (line 46).

Reviewer 2. This aspect is stressed by also other auhtors that found a variation among the almond cultivars in CR about 40% and on HR about 25% of variability. To reinforce this statement, I suggest to consider L. Gaeta, A.M. Stellacci and P. Losciale (2018). Comparison between two methods of estimation of chilling and heat requirements for flowering in almond. Acta Hortic. 1229. DOI 10.17660/ActaHortic.2018.1229.21

Authors´ answer: We appreciate this comment, we have change the sentence to clarify that HR also affects flowering, but in a minor way than CR. In addition we have cite the paper that you pointed in your comment (lines 63 and 64).

Reviewer 2. The authors should write the M&M section better. For example what kind of surveys were performed? Example: monitoring of bud fall, how many trees, how many buds per tree?

Authors´ answer: Thank you for this comment, there are not any official surveys about the frost. We have specified in the material and methods section the amount of trees that were considered from each cultivar (lines 89 and 90).

Reviewer 2. Please, the authors should specify the year in the M&M section, not just in the abstract.

Authors´ answer: Thanks, we have specified the year of the study in the materials and methods section (lines 93 and 94).

 

 

 

 

Reviewer 2. I'm sorry, I don't understand this phrase. Please the authors can explain better:

- Did you use the same methodology that used by Egea et al (2003) to calculate CR, also to individuate the date of end of endodormancy? In this case, the authors could be explain how many years are used for obtained this results. Only 2021?

- Or, did you use the results obtained by Egea et al. (2003) to found the budburst date? In this case the CU value for Extra-early (Desmayo Largueta) is different respect the value of Egea et al. (2003): 270 vs 309 CU. Moreover, the paper mentonied not report the whole cultivars considered.

Another point is: the CR is cultivar-specific, for this I suggest to use the name of cultivar in the table 1 and not the groupe of flowering time.

Authors´ answer: We are grateful for this comment, we used both the results obtained by Egea et al. (2003), as well as the data that we had from previous studies and previous years in the ITAP field to established the CR from each cualtivar (line 104). We rather use the name of the cultivar group, since more than one cultivar were observed in the groups. The example of some of the studied cultivars were added because they are very wellknown cultivars in this area and we considered that I may help to the reader to understand what do we mean by extra-early, early, late, extra-late and ultra-late.

Reviewer 2. Please put the reference number 12.

Authors´ answer: Thanks, we have added the reference 12 where you pointed (line 107).

Reviewer 2. How did the autors determine the percentage of covered heat requirements? They consider the heat requirements values calculated in Egea et al. (2003) as a starting point? In this case, please to see the previous comment (rows 94-97). It is not clear.

Authors´ answer: Thank you for your comment, as we previously specified, we considered the paper from Egea et al. (2003), as well as other previous experience and information from this field (line 104).

Reviewer 2. Please, see the previous comment about the table 1, in rows 94-97.

I try to explain better: there is only one representative cultivar of each group. I think 5 cultivars represent different flowering times but the CR is cultivar-specific. If the authors affirm that 270CU represents the CR of all the group of extra-early cultivars (for example) would not be correct. it is more correct indicate the cultivar Desmayo Largueta with 270CU and  in brackets the authors could indicate it as extra-early cultivar.

Please to correct in the whole text in this sense.

Authors´ answer: We appreciate this comment, as we pointed before, there were more than one cultivar per group. We just metioned one of the most popular cultivars from each group as a reference of each group.

Reviewer 2. I think it is useful to undertand the extent of the damages. The extra-early and early (100% of damage), late (few?)and extra and ultra-late (0%). Anyway, I suggest to use the names of the cultivars.

Authors´ answer: We are grateful for this comment, we have added the percentage of damage for each cultivar group (lines 118-120). As we explained before, we believe that we should keep the cultivar groups, since there is not just one cultivar per group.

Reviewer 2. It is possible individuate the predict date of blooming if we known the CR and HR values (previous calcultated). In this paper is not clear if uses CR and HR values already calculated or not. If the author calculated the CR and HR in this study is not clear how they calculated the heat requirement, in particular for extra-early and early cultivars when the frost damage is 100%. How did they predict the blooming date if whole flowering bud had fallen? The GDH calculation ends when occurs the full bloom (50% opened flower). Please to cleary this aspect.

Authors´ answer: We appreciate this comment, in this work, we determined the CR based on the previous knowledge that we have from previous works. The flowering date was determined based on previous data from these filed from the extra-early and early cultivars. For late, extra-late and ultra-late cultivars, we observed the flowering date on the field. We considered that the flowering date was the date, in which the 50% of the flowers were opened, we have clarified this in the manuscript (line 133).

 

 

 

 

 

 

 

Reviewer 2. According to Ruiz et al. 2007 the relationship between CR and flowering time was higer than HR and flowering time. Indeed, besides temperature, other variables could play a role in breaking dormancy and blooming processes. The knowledge about the different mechanisms are still under to evaluate. However, the complex phenomena of breaking dormancy and blooming generally were simplified using what was reasonably considered the main driving factor (temperature). I suggest to consider this paper Gaeta, L., Stellacci, A.M., Losciale, P., 2018. Evaluation of three modelling approaches for almond blooming in Mediterranean climate conditions. Eur. J. Agron. 97, 1–10. https://doi.org/10.1016/j.eja.2018.04.005.

Authors´ answer: Thank you for this comment, we have pointed to the existance of more factors that may be involved in flower development and we have cite the paper that you point in your comment (lines 149-151).

Reviewer 2. January 12 is still midwinter.

However, it is possible to affirm that if the temperatures reach very low values ​​(eg -20 ° C) when the cultivars have just come out of dormancy (extra-late) or are still dormant (ultra-late) they could not display frost damages. So I`m agree with the authors on early frost, but how do the authors assert that these cultivars can be the solution to the risks of late spring frosts? In this work, the authors had evaluated the early risk damage.

Authors´ answer: We appreciate this comment, many different works, as well as almond sector have discussed the great effectiveness of extra and ultra-late cultivars against late frost. In fact, this year (2022) the only almond cultivars that survived the late frost from April in Castilla la Mancha region were the extra and ultra late cultivars. We believe that it has been widely demonstrated along the last decades that these kind of cultivars are useful to avoind this kind of frost.

Reviewer 2. Please the authors could explain better this sentence. It is not clear.

Authors´ answer:  Thanks for this comment, we have delete the first sentence of the conclusions and we have rewrite this sentence (lines 175-187).

Author Response File: Author Response.docx

Reviewer 3 Report

Here the authors have done a small study looking at the effect of an unusual frost event on the flower development in almond. They have looked at factors which would improve resistance to these type of cold events, and suggest that these cultivars would be best positioned to be used in areas where late frosts are expected.

Major comments;

You mention that this frost event had a major impact on early and late flowering almond cultivars but there is no results to support this claim. Do you have any yield data from these cultivars? Any pictures showing the flowers failing from the early/late but not the ultra late? Or pictures showing almonds growing on the tolerant varieties but not the sensitive varieties. Do you know what stage the buds were in during the frost event in the different cultivars? Or can you correlate % of HR to stage of endodormancy to predict what stage they should have been at?

3.1 Bud fall – any results to support this? Percentage of late cultivars that kept a few – any pictures to represent the differences if not done any counting other than observation?

 

Minor comments;

Table 2: I would rename Flowering date to Predicted Flowering date

 

Line 9, 14, 18 – Missing a space after a full stop.

Line 11 – Missing ^o

Line 13, 77 – Missing a space between words

Line 16 – should heat requirements have capital letters?

Line 17 – requirement spelled wrong

Line 25 – Prunus dulcis

Line 34 – To many spaces after full stop

Line 36 – Sentence does not make sense – is the processed governed separately by each bud on a tree?

Line 58 – extra space before the full stop

Line 68, 140, 141 – evolution is the wrong word, I assume you mean development?

Line 69 – remove the word “being”

Line 70 – referencing hasn’t occurred correctly

Line 73 – ‘for’ rather than ‘of’

 

Author Response

Independent Review Report, Reviewer 3
EVALUATION

Here the authors have done a small study looking at the effect of an unusual frost event on the flower development in almond. They have looked at factors which would improve resistance to these type of cold events, and suggest that these cultivars would be best positioned to be used in areas where late frosts are expected.

Reviewer 3. You mention that this frost event had a major impact on early and late flowering almond cultivars but there is no results to support this claim. Do you have any yield data from these cultivars?

Authors´ answer: Thank you for your question, as far as we are concerned there is not official data about the damage produced by the frost in each particular cultivar, but this is a very wellknown fact by the productors of this area.

Reviewer 3. Any pictures showing the flowers failing from the early/late but not the ultra late? Or pictures showing almonds growing on the tolerant varieties but not the sensitive varieties.

Authors´ answer: Thank you for your comment, we made some photos of the frost and its consecuences  https://drive.google.com/open?id=1XEVeUOcp3zv-FukGmkVpi9VOlZxYX4QL&authuser=fdicenta%40gmail.com&usp=drive_fs

Photo 0: General overview  of the fields during the frost.

Photo 1: Effects of the early frost in olive trees.

Photo 2A: Damages observed in the late cultivar Lauranne, where all flower buds fall due to the frost. B: Flower buds from the extra-late cultivar Penta with no damage observable. Both photos were taken on March 10

Photo 3: Extra-late cultivar Penta during flowering time. This photo was taken on March 26.

Photo 4A: Poor production of the late cultivars Avijor-Lauranne. B Usual production of the extra-late Penta cultivar.

However, we believe that it might not be necessary to add any of these photos to the paper.

Reviewer 3. Do you know what stage the buds were in during the frost event in the different cultivars? Or can you correlate % of HR to stage of endodormancy to predict what stage they should have been at?

Authors´ answer: We are gratefull for your comment, during the frost flower buds were undeveloped (between A and C state defined by Felipe (1977). However, there was not a phenological observation about the state each cultivar flower buds during the frost.

Author Response File: Author Response.docx

Reviewer 4 Report

In this manuscript, the authors evaluated how storm Filomena (in 2021) affected the chilling accumulation and heat accumulation in five almond cultivars, including the extra-early flowering cultivar Desmayo Largueta, the early flowering cultivar Marcona, the late flowering cultivar Ferragnès, the extra-late flowering cultivar Penta, and the ultra-late flowering cultivar Tardona. For each of these cultivars, the authors reported the endodormancy release date in relation to the timing of the frost periods caused by storm Filomena. The authors also reported the percentage of heat requirements met by the frost dates. The authors concluded that extra- and ultra-late cultivars were more resistant to cold compared with other cultivars.

Overall, this work highlights the importance of the selection of extra- and ultra-late cultivars in coping with extreme frost events. However, my major concern is that the manuscript did not include any quantitative data reporting the flowering rate or the flower quality to directly support the cold resistant feature of the extra- and ultra-late cultivars. I believe that the soundness of the manuscript would be greatly improved if the authors can provide data on flowering and quantitatively evaluate frost damage.

Below are some minor concerns on the current manuscript:

(1)   Title: The phrase “extreme early frosts” in the title is somewhat confusing. The manuscript examines the effects of storm Filomena that occurred in January 2021, after the endodormancy release dates of extra-early, early, late, and extra-late almond cultivars, but before the endodormancy releases date of the ultra-late cultivar. Should such frosts be considered as early or late frosts? How about removing the word “early” from the title, or changing the title to something like “Impacts of storm Filomena on Flowering in Five Almond Cultivars”?

(2)   Page 2 Figure 1: It would be very helpful if the authors can briefly explain each of the phenological states shown in the figure. Currently, it is unclear if state A is the “total endodormant flower bud” and state F is the “open flower”, as referred in the figure legend.  

(3)   Page 3 lines 86 – 91. Please specify in which year the measurements were performed. Were they take in 2021 (when the Storm Filomena hit) or throughout multiple years?

(4)   Page 3 Table 1: Inconsistent abbreviations for chilling requirements: the abbreviation “CR” was used throughout the main text, but the abbreviation “CU” was used in the table.

(5)   Page 4 Figure 2: What does “CP” – the label on the Y axis on the right indicate/mean?

Author Response

Independent Review Report, Reviewer 4
EVALUATION

In this manuscript, the authors evaluated how storm Filomena (in 2021) affected the chilling accumulation and heat accumulation in five almond cultivars, including the extra-early flowering cultivar Desmayo Largueta, the early flowering cultivar Marcona, the late flowering cultivar Ferragnès, the extra-late flowering cultivar Penta, and the ultra-late flowering cultivar Tardona. For each of these cultivars, the authors reported the endodormancy release date in relation to the timing of the frost periods caused by storm Filomena. The authors also reported the percentage of heat requirements met by the frost dates. The authors concluded that extra- and ultra-late cultivars were more resistant to cold compared with other cultivars.

Reviewer 4. Overall, this work highlights the importance of the selection of extra- and ultra-late cultivars in coping with extreme frost events. However, my major concern is that the manuscript did not include any quantitative data reporting the flowering rate or the flower quality to directly support the cold resistant feature of the extra- and ultra-late cultivars. I believe that the soundness of the manuscript would be greatly improved if the authors can provide data on flowering and quantitatively evaluate frost damage.

Authors´ answer: We are gratefull for this comment, we have added the percentage of the flowerbuds that were destroyed in each cultivar group by the frost.

Reviewer 4. Title: The phrase “extreme early frosts” in the title is somewhat confusing. The manuscript examines the effects of storm Filomena that occurred in January 2021, after the endodormancy release dates of extra-early, early, late, and extra-late almond cultivars, but before the endodormancy releases date of the ultra-late cultivar. Should such frosts be considered as early or late frosts? How about removing the word “early” from the title, or changing the title to something like “Impacts of storm Filomena on Flowering in Five Almond Cultivars”?

Authors´ answer: Thank you for this comment, this frost should be considered an early frost, because it takes place in the mid January, just after the Filomena storm. We believe that this frost should be classified as an ealy frost, since late frost usually take place during the end of March or the begging of April.

Reviewer 4. Page 2 Figure 1: It would be very helpful if the authors can briefly explain each of the phenological states shown in the figure. Currently, it is unclear if state A is the “total endodormant flower bud” and state F is the “open flower”, as referred in the figure legend.  

Authors´ answer: We appreciate this comment, we have explained every state of figure 1 in its caption.

Reviewer 4. Page 3 lines 86 – 91. Please specify in which year the measurements were performed. Were they take in 2021 (when the Storm Filomena hit) or throughout multiple years?

Authors´ answer: Thank you for your comment, we have added the year of the measurements (lines 92 and 93)

Reviewer 4. Page 3 Table 1: Inconsistent abbreviations for chilling requirements: the abbreviation “CR” was used throughout the main text, but the abbreviation “CU” was used in the table.

Authors´ answer: We are gratefull for this comment, this was our mistake chill units (CU) are the unit for measuring chill accumulation. We have added the meaning of CU in the manuscript.

Reviewer 4. Page 4 Figure 2: What does “CP” – the label on the Y axis on the right indicate/mean?

Authors´ answer: Thank you for this comment, this was our mistake. CP should not be in the figure. We have added a new version of the figure without CP.

 

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Thank you for your response to my questions and your edits to the text. I personally would like to include 2A, B and 4A, B within the text, as this supports your claim of damage to the buds due to the frost, and something visual is always easier to understand than text. But I understand that it is only a short communication piece and therefore you may not have the space or be able to add it as a supplementary file.