Crop Load Affects Yield, Fruit Size, and Return Bloom of the New Apple Cultivar Fryd© (‘Wuranda’)
Round 1
Reviewer 1 Report (New Reviewer)
Comments and Suggestions for AuthorsMain issues:
- Crop load is one of the most important factors influencing the source-sink relationship of fruit trees. Compared with the control group, are there any differences in indicators such as leaf area index and photosynthetic rate in the treatment group?
- In the caption of Figure 5, there is an error in the annotation of “>60 mm”.
- In Figure 6, from 2021 to 2023, the soluble solid content of the fruits in the low-load group showed a decreasing trend year by year. The factors that might have caused this phenomenon should be further explored and analyzed.
- The font and formats in all figures and tables should be consistent.
Author Response
Dear reviewer, we are very thankful for your thorough review and suggestions how to improve our paper. We accepted your remarks and made corresponding changes in the text according to your suggestions. In some cases, we can’t make changes, and our explanation for that is provided in our answers to your remarks.
- Crop load is one of the most important factors influencing the source-sink relationship of fruit trees. Compared with the control group, are there any differences in indicators such as leaf area index and photosynthetic rate in the treatment group?
We totally agree that physiological investigations could add more information in our study. Unfortunately, we cannot provide additional data related to plant physiological responses, since we did not conduct such experiments. Your suggestion will be taken on account in our other ongoing trials. However, compared to the very first version, this manuscript according to the reviewers’ suggestions was expanded by the discussions related to crop load physiology, leaf to fruit ratio, moreover, we added discussions about chlorophyl degradation, metabolites, carbon partitioning, hormone signalling, etc.
2. In the caption of Figure 5, there is an error in the annotation of “>60 mm”.
The annotation in Figure 5 (now Figure 7) was changed to “<60 mm”.
3. In Figure 6, from 2021 to 2023, the soluble solid content of the fruits in the low-load group showed a decreasing trend year by year. The factors that might have caused this phenomenon should be further explored and analyzed.
Thank you for your valuable comment. Yes, indeed SSC at low crop level (CL) was decreasing over the years of our study (11.7 – 11.2 – 10.63%). The same decreasing trend of SSC was observed at medium CL (11.5 – 11.1 – 10.83) and at high CL (11.6 – 11.0 – 10.37). This variation can be related to the growing season conditions, some variation of harvest time, but not to the crop load level, since there were no significant differences between CL in any of particular seasons.
Following explanation added to the Discussion section: ‘A decreasing trend in SSC was noticed over the trial period at all crop load levels, however it can be related to the variation in weather conditions, and in harvest timing in different years of the study.’
4. The font and formats in all figures and tables should be consistent.
The font in all tables and figures changed into Palatino Linotype, font size 10.
Reviewer 2 Report (New Reviewer)
Comments and Suggestions for AuthorsThis is a well-executed study that deals with an important and practical topic in apple production: how crop load influences yield, fruit size, and return bloom, particularly in a newer cultivar like 'Fryd' that seems to have a tendency toward biennial bearing.
The multi-year trial design, using crop load levels based on TCSA (trunk cross-sectional area), is solid and aligns with good experimental practice. The data are clearly presented, the analysis is straightforward, and the message comes through clearly — reducing crop load improves fruit size and return bloom, but too light a load sacrifices total yield.
That said, there are a couple of key details missing that should be addressed:
- There's no mention of orchard age in the abstract or methods section. It becomes somewhat clear later in the paper that the trees were 3–5 years old, but this should be explicitly stated up front. Tree age can significantly affect responses to thinning, especially in young or non-bearing orchards.
- The type of soil is also not described, nor are any site characteristics (soil texture, fertility, pH, or irrigation practices). These factors can heavily influence tree vigor, fruit development, and flowering responses. Without this context, it’s hard to judge how transferable the findings are to other production systems.
The study is well structured, and the figures/tables are helpful.
The link between crop load and return bloom is clearly shown, and it's great that the authors focus on fruit number per TCSA rather than yield per se — that’s in line with what growers and researchers observe in practice.
The cultivar being studied is relatively new, so this adds value to the literature.
Some Suggestions:
Add a brief paragraph in the methods section describing soil type and orchard site characteristics.
Be clear from the start about tree age and rootstock.
Consider expanding the discussion to include how these results might differ in other environments or production systems.
This is a useful and timely study, especially for growers dealing with alternate bearing in new apple cultivars. With just a few tweaks — mostly around context and clarity — it would be a strong contribution to the field.
Author Response
Dear reviewer, we are very thankful for your thorough review and suggestions how to improve our paper. We accepted your remarks and made corresponding changes in the text according to your suggestions.
Some Suggestions:
- Add a brief paragraph in the methods section describing soil type and orchard site characteristics.
Following description is added in the M&M section: ‘The soil is sandy loam, slightly acidic (pH 5.54), with 5.54 % organic matter content. The orchard is drip irrigated with 0.5 m drip spacing’.
- Be clear from the start about tree age and rootstock.
Following information is included in the abstract: ‘The apple cultivar Fryd (‘Wuranda’) was propagated on ‘M.9‘ rootstock and planted in 2019. The trial was performed in the same orchard for four consecutive years, starting three years after planting’.
Following information is included also in M&M section: ‘The trial was performed in the same orchard for four consecutive years, starting three years after planting’.
- Consider expanding the discussion to include how these results might differ in other environments or production systems.
Discussion section was modified by adding discussions on crop load effect on the ‘Honeycrisp’ and ‘Honeycrisp’ related cultivars in different climates: ‘Optimal yield to keep the orchard in annual fruiting mode depends on many factors. Cultivar genetics plays an essential role in this, but even the same cultivar on different planting and training systems, or exposed to different orchard management and, moreover, in different climate conditions can have significantly different yields. It was noticed in EUFRIN multilocation apple rootstock trials that the yield of cv. ‘Galaval’ on the same rootstock varied between countries significantly, and when comparing Norway with some southern European countries, 2-3-fold lower yields were achieved [41]. The yield of ‘Honeycrisp’ and related cultivars can differ due to growing site or orchard management. In Washington state ‘Honeycrisp’ planted at 2.5 × 0.9 m spacing produced yields between 29 t⋅ha−1 and 76 t⋅ha−1 depending on the crop load level [14], while ‘WA38’ produced stable yields of 80 t⋅ha−1 [3]. In a cooler, maritime climate of Nova Scotia, Canada the yield of ‘Honeycrisp’ (22 – 32 t⋅ha−1) was similar to our trial results, however trees were grafted on M.26 rootstock and planted at broader distances [16]. In Norwegian growing conditions with a shorter, cooler growing season, there is a yield limit of 30 t ha-1 for five-year-old cv. Fryd to maintain a regular bearing pattern; 35 t ha-1 and higher yields turn the trees towards biennial bearing. Additionally, a steady yield increase according to the orchard age is very important to maintain regular bearing of cv. Fryd.‘
Reviewer 3 Report (New Reviewer)
Comments and Suggestions for AuthorsThis manuscript reports on the effects of crop load in Norway on the yield, fruit size, and greening of the new apple variety Fryd©, which has certain reference value for apple production in cold regions around the world. However, this manuscript still has the following defects and issues:
1 Provide a more detailed explanation of the varieties related to "Honeycrisp" (including "Fryd©") The specific challenges faced in terms of two-year fertility and how to address these challenges in previous research may benefit it. In addition, including recent (within the past 5 years) references related to crop load management and its impact on apple productivity and fruit quality will strengthen the background.
- Lack of geographical location maps of the apple orchards studied (county, province, and nearby major cities), which is not very user-friendly for readers unfamiliar with Norwegian geography.
- Lack of photos of the apple variety Fryd, such as tree shape, leaves, flowers, and fruits (it would be better if relevant information about its parents SQ159 and 'Honeycrisp' could be provided).
- How many apple trees are surveyed for each crop load level? How to accurately determine the number of fruits per tree? What if the fruit falls off during the fruiting period due to natural disasters or physiological reasons?
- Is it better to replace 'biennial bearing' with 'alternate bearing'?
- After the mean values in Tables 2-4, "± standard deviation" should be added.
- The maximum yield of crop load treatment in three years was significantly lower than the control, does this indicate that the level of crop load was set too low?
- From the perspective of economic value, explain whether the crop load level set in the experiment has more advantages. nine The linear regression coefficient (R2) in Figure 8 is not large, and a linear relationship test is needed.
- Discuss the potential impact of Norway's climate conditions (such as temperature and precipitation) on the experimental results, and whether there are differences from relevant studies in temperate regions.
The language of the manuscript can be further improved.
Author Response
Dear reviewer, we are very thankful for your thorough review and suggestions how to improve our paper. We accepted your remarks and made corresponding changes in the text according to your suggestions. In some cases, we can’t make changes, and our explanation for that is provided in our answers to your remarks.
1. Provide a more detailed explanation of the varieties related to "Honeycrisp" (including "Fryd©") The specific challenges faced in terms of two-year fertility and how to address these challenges in previous research may benefit it. In addition, including recent (within the past 5 years) references related to crop load management and its impact on apple productivity and fruit quality will strengthen the background.
Following paragraph is added into Introduction: In recent years many breeding companies around the world have included cv. ‘Honeycrisp’ in their breeding programs, resulting in many new cultivars with ‘Honeycrisp’ in their pedigree having been released. Examples include Cosmic Crisp® (‘WA38’) from Washington State University, SweeTango® (Minneiska) from University of Minesota , SnapDragon® from Cornell University, and EverCrisp® from Midwestern Apple Improvement Association; these and other similar cultivars have been planted extensively in the US and other countries. Due to a short history of these cultivars limited studies have been published, and only one is related to crop load studies of apple cultivar ‘WA38’ [3].’
Regarding new references, we strongly believe that the newest publications are included in our manuscript. 28 references out of 41 papers were published during the last 5 years. In our discussions about crop load management, tree productivity, crop load impact on fruit quality, return bloom we used 21 newly published papers.
2. Lack of geographical location maps of the apple orchards studied (county, province, and nearby major cities), which is not very user-friendly for readers unfamiliar with Norwegian geography.
Map of Northern Europe with indicated trial site is added in M&M section as Figure 1. Additional information on county and commune is added in M&M section: ‘…in commercial fruit farm in Westland County, Ullensvang commune, Norway (60°34'57.0"N 6°62'40.0"E)’.
3. Lack of photos of the apple variety Fryd, such as tree shape, leaves, flowers, and fruits (it would be better if relevant information about its parents SQ159 and 'Honeycrisp' could be provided).
Photos of Fryd tree added in M&M section: ‘Figure 2. Cv. Fryd tree training, flowering, fruit set and fruits at harvest.’
We think that similar pictures of Fryd parent cultivars SQ159 and 'Honeycrisp' could be more related to the genetic studies and will not provide additional value for our manuscript about crop load management.
4. How many apple trees are surveyed for each crop load level? How to accurately determine the number of fruits per tree? What if the fruit falls off during the fruiting period due to natural disasters or physiological reasons?
Eight similarly growing and flowering trees were selected every year for each crop load level. It is indicated in M&M section: ‘Each crop load level was replicated eight times, with a single tree per plot…’. Every year fruit clusters were counted on individual tree and thinned firstly to one fruit per cluster. Then, fruit number was adjusted to the certain crop load level. Since, thinning was performed at the fruitlet size 15-20 mm and a single strong growing king fruit was retained, natural fruit drop was minimised. Only, in 2022 some fruits were lost due to mechanical or insect damages, but, even then, fruit drop was similar on all trees in the experiment.
5. Is it better to replace 'biennial bearing' with 'alternate bearing'?
Both definitions are used in scientific papers, however 'biennial bearing' is more common. To be consistent, we replaced in the text 'alternate bearing' with 'biennial bearing' (3 changes made).
6. After the mean values in Tables 2-4, "± standard deviation" should be added.
Standard deviation values added in Tables 2-4.
7. The maximum yield of crop load treatment in three years was significantly lower than the control, does this indicate that the level of crop load was set too low?
Fruitlet thinning was not applied in control trees during the first two years of experiment, or fruits were thinned to one fruit per cluster in the last year of experiment. No thinning or very mild thinning led to the maximum yield per tree, and it was always higher comparing to the trees where crop load was regulated to different levels. Chosen crop load levels were not too low, since they let us to establish a level from which trees turned to biennial bearing.
8. From the perspective of economic value, explain whether the crop load level set in the experiment has more advantages. nine The linear regression coefficient (R2) in Figure 8 is not large, and a linear relationship test is needed.
Following paragraph added into Discussions section:
‘Establishing optimal crop load level according to orchard age combines as high as possible yield of high-quality fruits and good return bloom. When optimal crop load is maintained, cv. Fryd does not turn to biennial bearing and guarantees stable incomes for the growers throughout the life of the orchard. Too low or too high crop load levels reduce profitability of apple fruit growing by lower yield value in the first case, or by possibly higher incomes only every second year in the second case, since poorer fruit quality at high crop load level can result in a reduction of marketable fruits.’
Correlation coefficients were added into Figure 8 (now Figure 10).
9. Discuss the potential impact of Norway's climate conditions (such as temperature and precipitation) on the experimental results, and whether there are differences from relevant studies in temperate regions.
Discussion section was modified by adding discussions on crop load effect on the ‘Honeycrisp’ and ‘Honeycrisp’ related cultivars in different climates: ‘Optimal yield to keep the orchard in annual fruiting mode depends on many factors. Cultivar genetics plays an essential role in this, but even the same cultivar on different planting and training systems, or exposed to different orchard management and, moreover, in different climate conditions can have significantly different yields. It was noticed in EUFRIN multilocation apple rootstock trials that the yield of cv. ‘Galaval’ on the same rootstock varied between countries significantly, and when comparing Norway with some southern European countries, 2-3-fold lower yields were achieved [41]. The yield of ‘Honeycrisp’ and related cultivars can differ due to growing site or orchard management. In Washington state ‘Honeycrisp’ planted at 2.5 × 0.9 m spacing produced yields between 29 t⋅ha−1 and 76 t⋅ha−1 depending on the crop load level [14], while ‘WA38’ produced stable yields of 80 t⋅ha−1 [3]. In a cooler, maritime climate of Nova Scotia, Canada the yield of ‘Honeycrisp’ (22 – 32 t⋅ha−1) was similar to our trial results, however trees were grafted on M.26 rootstock and planted at broader distances [16]. In Norwegian growing conditions with a shorter, cooler growing season, there is a yield limit of 30 t ha-1 for five-year-old cv. Fryd to maintain a regular bearing pattern; 35 t ha-1 and higher yields turn the trees towards biennial bearing. Additionally, a steady yield increase according to the orchard age is very important to maintain regular bearing of cv. Fryd.‘
The language of the manuscript can be further improved.
The language of added paragraphs or modified sections was checked by native American colleague.
Round 2
Reviewer 3 Report (New Reviewer)
Comments and Suggestions for AuthorsAlthough the manuscript has made significant improvements, there are still some obvious errors or issues:
- In the legend of Figure 2, the second "C)" should be changed to "E)".
- The "Sep" in Figures 3 and 4 is inconsistent with the "Sept." in Table 1.
- The biggest weakness of this manuscript is that the recommended optimal crop load in the experiment cannot be demonstrated by yield or economic benefits.
- The "p" in the "p<0.05" included in the annotations of some charts and tables should be italicized.
- The title of the third image in Figure 9, 'High Cl', should be changed to 'High CL'.
- The 'Crop load level' in Table 4 should be centered for better aesthetics.
- The r values on the first and third graphs in Figure 10 are reversed, and the correlation test is not labeled for the r values on all three graphs to determine if they are significant.
- The "-1" in line 373 "(22-32 t ⋅ ha − 1)" does not have a superscript.
- In references 31, 34, 36, 37, and 40, the format of DOI is different from that of other references. It is recommended to conduct a comprehensive review.
The language of the manuscript deserves further revision.
Author Response
Dear reviewer. Thank you again for your time spend and comments how to improve our manuscript.
Our answers and explanations provided below.
- In the legend of Figure 2, the second "C)" should be changed to "E)".
Changed.
2. The "Sep" in Figures 3 and 4 is inconsistent with the "Sept." in Table 1.
‘Sept’ in Table 1 replaced by ‘Sep.’ Totally, 3 changes done.
3. The biggest weakness of this manuscript is that the recommended optimal crop load in the experiment cannot be demonstrated by yield or economic benefits.
We agree that economical evaluation could be included in our study. We tried to explain possible benefits by extending discussions (‘Establishing optimal crop load level according to orchard age combines as high as possible yield of high-quality fruits and good return bloom. When optimal crop load is maintained, cv. Fryd does not turn to biennial bearing and guarantees stable incomes for the growers throughout the life of the orchard. Too low or too high crop load levels reduce profitability of apple fruit growing by lower yield value in the first case, or by possibly higher incomes only every second year in the second case, since poorer fruit quality at high crop load level can result in a reduction of marketable fruits.’)
Results of crop load level and it’s impact on yield is presented in the section 3.6. Return bloom. At the end of Discussion section, we wrote about possible yields too: ‘In Norwegian growing conditions with a shorter, cooler growing season, there is a yield limit of 30 t ha-1 for five-year-old cv. Fryd to maintain a regular bearing pattern; 35 t ha-1 and higher yields turn the trees towards biennial bearing. Additionally, a steady yield increase according to the orchard age is very important to maintain regular bearing of cv. Fryd.’
4. The "p" in the "p<0.05" included in the annotations of some charts and tables should be italicized.
The "p" replaced by "p" in all charts and tables
5. The title of the third image in Figure 9, 'High Cl', should be changed to 'High CL'.
'High Cl' in the third image in Figure 9, replaced by 'High CL'.
6. The 'Crop load level' in Table 4 should be centered for better aesthetics.
Changed.
7. The r values on the first and third graphs in Figure 10 are reversed, and the correlation test is not labeled for the r values on all three graphs to determine if they are significant.
Can it be some kind of nonunderstanding? r values in all three graphs in Figure 10 are similar: - 0.61; - 0.66; - 0.70. Are two of them reversed?
Values are labelled by *, which indicates that they are significant at p < 0.05.
8. The "-1" in line 373 "(22-32 t ⋅ ha − 1)" does not have a superscript.
"(22-32 t ha − 1)" replaced by ‘(22 – 32 t⋅ha−1)’
9. In references 31, 34, 36, 37, and 40, the format of DOI is different from that of other references. It is recommended to conduct a comprehensive review.
DOI format of references 31, 34, 36, 37, and 40 changed. After the review of the rest of references, DOI format of reference 8 changed too.
The language of the manuscript deserves further revision.
Language was revised.
All corrections and changes are in the text attached.
Author Response File: 
Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis is an interesting study reporting new data of relevance to apple growers in northern conditions. The study is very well planned and performed. The manuscript is also well written and clear, summarizing the results in a logic manner and easy to read and understand. Conclusions are supported by data. There are just a few editorial issues in the manuscript to consider as follows.
In the paper (and the title) Fryd is mentioned as a cultivar although it is a registered trade mark. This is also true for some of the other denominations of cultivars in the paper. For clarity I suggest that what is now referred to as cv. 'Fryd' should be written as cv. Fryd© when first mentioned and then use cv. Fryd or cv. Fryd('Wuranda') throughout the text.
Below are suggestions for editorial corrections.
R3 Replace ” ’Fryd’ ” with ”Fryd©”
R12 Replace ” ’Fryd’ ” with ”Fryd©”
R18 Replace ” ’Fryd’ ” with ”Fryd”
R21 Replace ” ’Fryd’ ” with ”Fryd”
R32 Replace ”Honeycrisp” with ” ’Honeycrisp’ ”
R34 Replace ”name ’Fryd’ ” with ”trade name Fryd©”
R42 Replace ”per cm-2” with ”per cm2”
R50 Replace ” ’Pink Lady’ ” with ” ’Cripps Pink’ (Pink Lady©)”
R56 Replace ” fruits/cm2 per” with ”fruits per cm2” or ”fruits cm-2”
R57 Replace ” fruits/cm2 per” with ”fruits per cm2” or ”fruits cm-2”
R59 Replace ”cv’Fryd’(’Wuranda’)” with ”cv. Fryd(’Wuranda’)”
R66 Replace ” ’Fryd’ ” with ”Fryd”
R113 Add a dot at the end of the legend.
R116 Add a dot at the end of the legend.
R131 Replace ” ’Fryd’ ” with ”Fryd”
R175 Replace ”determined” with ”resulted in”
R177 Replace ”felt” with ”fell”
R178 Replace ”felt” with ”fell”
R184 Replace ” ’Fryd’ ” with ”Fryd” and add a dot at the end of the legend.
P7 Adjust Figure 6, year 2022 so that the whole Figure and text is visible. Also adjust the significance letters for year 2022 and 2023 to the lines.
R240 Replace ”of” with ”a”
R250 Replace ”Cl” with ”CL”
R251 Replace ” ’Fryd’ ” with ”Fryd”
R260 Replace ” ’Fryd’ ” with ”Fryd”
R262 and 263 Replace ”Only in not favour for fruit growth season in 2022” with ”Only in 2022, when the season was not favourable for fruit growth,”
R271 Replace ”no impact” with ”little impact”
R272 Replace ” ’Fryd’ ” with ”Fryd”
R279 Replace ” ’Fryd’ ” with ”Fryd”
R309 Replace ” ’Fryd’ ” with ”Fryd”
R312 Replace ” ’Fryd’ ” with ”Fryd”
R316 Replace ” ’Fryd’ ” with ”Fryd”
R323 Replace ” ’Fryd’ ” with ”Fryd”
R326 Replace ” ’Fryd’ ” with ”Fryd”
R330 Replace ” ’Fryd’ ” with ”Fryd”
R332 Replace ” ’Fryd’ ” with ”Fryd”
Author Response
Dear reviewer,
thank you for your time preparing so thorough review.
Comment 1. For clarity I suggest that what is now referred to as cv. 'Fryd' should be written as cv. Fryd© when first mentioned and then use cv. Fryd or cv. Fryd('Wuranda') throughout the text. Response 1. Throughout the text we changed denominations of cv. Fryd and other cultivars as you suggested.
Comment 2. Add a dot at the end of the legend.
Response 2. Dots added to all legends.
Comment 3. Adjust Figure 6, year 2022 so that the whole Figure and text is visible. Also adjust the significance letters for year 2022 and 2023 to the lines.
Response 3. Figure 6 is corrected.
Comment 4. Suggestions to change words phrases. Replace ”per cm-2” with ”per cm2”. Replace ” fruits/cm2 per” with ”fruits per cm2” or ”fruits cm-2 . Replace ”determined” with ”resulted in”. Replace ”felt” with ”fell”. Replace ”of” with ”a”. Replace ”Cl” with ”CL”. Replace ”Only in not favour for fruit growth season in 2022” with ”Only in 2022, when the season was not favourable for fruit growth,”. Replace ”no impact” with ”little impact”.
Response 4. Thank you again for your kind editing of our paper. We made all changes according to your comments.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper investigates the effects of crop load on yield, fruit size, and return bloom in the new apple cultivar 'Fryd' ('Wuranda'), aiming to establish optimal crop load levels to ensure consistent productivity and fruit quality. The study is well-designed, with detailed data, and the conclusions provide practical guidance. However, there are several areas where the paper could be improved:
1. The background information on the 'Fryd' cultivar is somewhat brief, particularly regarding its relationship with 'Honeycrisp' and its market potential in Norway. It would be beneficial to include more details on market demand and consumer preferences for this cultivar to enhance the practical relevance of the study.
2. The paper mentions that crop load levels were adjusted based on tree age, but it does not elaborate on the rationale behind the specific crop load levels chosen. It would be helpful to provide more information on the basis for selecting these levels.
3. The analysis of fruit quality parameters is relatively brief, particularly regarding the impact of crop load on fruit quality. While the paper states that crop load had no significant effect on fruit quality parameters, it does not delve into potential reasons. Further analysis of the relationship between crop load and fruit quality.
4. Why is the 2022 data missing from the fruit growth dynamics in the result sections.
5. The discussion section is somewhat limited in its interpretation of the results, particularly regarding the relationship between crop load and return bloom. It would be beneficial to explore the physiological mechanisms underlying the impact of crop load on return bloom in more depth, possibly by referencing similar studies and discussing hormonal regulation and resource allocation.
Author Response
Dear reviewer, we are very thankful for your comments and suggestions to improve our manuscript. Please, find our explanations to your comments.
Comment 1. The background information on the 'Fryd' cultivar is somewhat brief, particularly regarding its relationship with 'Honeycrisp' and its market potential in Norway. It would be beneficial to include more details on market demand and consumer preferences for this cultivar to enhance the practical relevance of the study.
Response 1. Following statements are added in Introduction: 'Despite of long fruit growing traditions in Norway locally grown apples have only 15-18 % share in the domestic market. The urgent task for research together with growers’ organisations and wholesalers is an introduction of new cultivars which can compete with imported apples.'
First sentence indicates what apple cultivars are preferred: 'New apple cultivars with high quality, tasty and crispy fruits and extended storage season are desirable in Norwegian market...'
As is mentioned in Introduction, cv. Fryd is a new cultivar, and cv. 'Honeycrisp' is one the parents. In the text we indicate that alternate bearing of cv Fryd is common with 'Honeycrisp' and other ‘Honeycrisp’ related cultivars. We did not mention other possible common disadvantages, stressing on our main goal - how to achieve cropping regularity.
Comment 2. The paper mentions that crop load levels were adjusted based on tree age, but it does not elaborate on the rationale behind the specific crop load levels chosen. It would be helpful to provide more information on the basis for selecting these levels.
Response 2. Sorry, for the lack of information. Our study was conducted in the same orchard. Investigations were started in 3-year-old orchard and finished in 6-year-orchard, and during this period apple trees reached allocated space in the orchard. Every year crop load levels (which were based on numerous studies with 'Honeycrisp') gradually increased according to the annual increase of trees (TCSA). Every year we were selecting similarly growing (and similarly flowering) trees for crop load studies. In the M&M section we added following information (line 83): 'Each year similarly growing trees were selected for the studies'.
Comment 3. The analysis of fruit quality parameters is relatively brief, particularly regarding the impact of crop load on fruit quality. While the paper states that crop load had no significant effect on fruit quality parameters, it does not delve into potential reasons. Further analysis of the relationship between crop load and fruit quality.
Response 3. Thank you for your insights. Received data was somewhat surprising for us too, and we found only two references with somewhat similar results. More detailed trials should be initiated to explain these findings. Relatively brief presentation of fruit internal quality parameters is because we did not find significant differences between crop load levels. However, our fruit quality results are discussed with 11 studies.
Comment 4. Why is the 2022 data missing from the fruit growth dynamics in the result sections.
Response 4. Sorry, we did not get reliable results of fruit growth in 2022 due to loss of significant part of marked fruits. Following explanation is provided in M&M: 'Due to the severe drop of marked fruits (due to mechanical or insect damage), fruit size recording was terminated in 2022.' (lines 102-103).
Comment 5. The discussion section is somewhat limited in its interpretation of the results, particularly regarding the relationship between crop load and return bloom. It would be beneficial to explore the physiological mechanisms underlying the impact of crop load on return bloom in more depth, possibly by referencing similar studies and discussing hormonal regulation and resource allocation.
Response 5. Thank you for your suggestion. Sorry to say, we did not conduct physiological studies and only some physiological aspects were mentioned in the text. We added in the text: ''Campbell and Kalcsits [30] in their review indicated two main theories explaining biennial bearing: phytohormone signaling, and resource competition for nutrients and carbohydrates. Though more knowledge on carbohydrate and hormone cycling/signaling are gained, still impact of crop load on return bloom is poorly understood.''
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors,
Thank you for your efforts on "Crop load affects yield, fruit size and return bloom of the new apple cultivars 'Fryd' ('Wuranda'). It is very interesting manuscript that tried to articulate crop loading physiology including, truck cross-sectional area (TCSA). In order to fulfil the main goal, however, the article need more work on crop loading in aspects of tree age and growing condition. Reviewer would like to share major and minor comments on this manuscript below:
Abstract:
Authors should revise the abstract. If it is 3-6 years-old orchard, how did you define they are new cultivars? or no one work on this? Don't add the acronym without addressing full form in abstract. For example, TCSA? In the conclude point, abstract should synchronize with the title, objective, and conclusion. Please revise line 21-22.
Introduction:
Line 39-40 needs reference.
Line 39-45 revise it. There some parts are redundant in here. Authors should add more details about thinning/ removing fruit on crop loading, percentage of fruit removal on leaf area, carbon assimilation, fruit size, and reblooming.
Line 54-56, is there any other physiological effects after TCSA? Please add it.
Please revise the main objectives after reading the whole manuscripts.
Materials and methods:
How was the size of the plot for a single tree? How were the height of the tree and canopy volume?
Is there any criteria to select of fruit trunk? If authors use same cultivars in different year, how did they maintained tree trunk size in every year for assessing fruit loading?
Results:
Figure 3 and 4 should revise and add y-axis. Where is 2022 fruit growth dynamic?
Reviewer anticipate that authors should add a standard fruit size group.
Figure 6 is ambiguous. Authors should revise it.
Lines 223-229 should revise with specific figure. These figures are ambiguous and don't contrast with other figures.
Discussion:
Authors should revise more on this section. for example, authors did not explain how fruit thinning and TCSA impact on leaf area and photosynthesis that are interrelated to reblooming and fruit size. Authors should discuss how fruit tree age correlate reblooming and fruit size.
Conclusion:
Authors should revise conclusion with objectives.
Best of luck!
Need English correction.
Author Response
Dear reviewer, we are very thankful for your comments and suggestions to improve our manuscript. Please, find our explanations to your comments.
Comment 1. Abstract:
Authors should revise the abstract. If it is 3-6 years-old orchard, how did you define they are new cultivars? or no one work on this? Don't add the acronym without addressing full form in abstract. For example, TCSA? In the conclude point, abstract should synchronize with the title, objective, and conclusion. Please revise line 21-22.
Response 1. Sorry, for not clear statement. Our investigations were performed in the same orchard starting from the third year after planting, when trees started to produce considerable amount of fruits. Crop load studies were continued in the same orchard for 3 years in the row, and the last return bloom data was recorded in the 6-year-old orchard. To avoid confusion, we deleted "3-6 years-old orchard" from the abstract text.
As is mentioned cv. Fryd ('Wuranda') was firstly planted in Norway in 2019. 'Wuranda' is till new cultivar in Europe and research results are not available.
Acronym TCSA is explained (trunk cross sectional area).
Lines 21-22 we moved to the middle of the text, added conclusion about crop load effect on fruit size variation and left main findings in the end of abstract. Abstract is synchronized with the title, objective, and conclusion.
Comment 2. Line 39-40 needs reference.
Response 2. References [4 - 7] are provided after the next statement (line 44) and they are covering both statements.
Comment 3. Line 39-45 revise it. There some parts are redundant in here. Authors should add more details about thinning/ removing fruit on crop loading, percentage of fruit removal on leaf area, carbon assimilation, fruit size, and reblooming.
Response 3. We think that statements in this paragraph are in a logical order. 1. Problem: biennial bearing. 2. Technological factors affecting biennial bearing with highlighted crop load. 3. And what strategies are used for regulation of crop load.
Thank you for your suggestion to add more details. Our intention was to discuss how various orchard management technics interact with bearing regularity. Indeed, we did not perform physiological or genetical investigations, however, most of your suggested topics are in Discussions part: lines 252-255 (fruit size. references: 13, 15-21), lines 258 - 260 (assimilates. references: 14,22), lines 290 -291 (hormones inhibitors. references: 31- 33). More topics as crop load effect on pre- and post-harvest fruit quality, effect on fruit maturation are discussed too.
Comment 4. Line 54-56, is there any other physiological effects after TCSA? Please add it.
Response 4. Here we concentrate on our main goal - to establish an optimal crop load and here we used references about 'Honeycrisp' as one of 'Fryd' parents. In the text we indicate that alternate bearing of cv Fryd is common with 'Honeycrisp' and other ‘Honeycrisp’ related cultivars. We did not mention other possible common disadvantages, stressing on our main goal - how to achieve cropping regularity. Other topics we left for Discussions what was explained in Response 3.
Comment 5. How was the size of the plot for a single tree? How were the height of the tree and canopy volume?
Is there any criteria to select of fruit trunk? If authors use same cultivars in different year, how did they maintained tree trunk size in every year for assessing fruit loading?
Response 5. Sorry, for the lack of information. Orchard was planted at 3.5x1 m distances. This will be a size of single tree plot. Investigations were started in 3-year-old orchard and finished in 6-year-orchard, and during this period apple trees reached allocated space in the orchard. Tree height at the beginning of investigations was 1.6-1.8 m, and 2.5-2.6 at the end of our trial. Trees were trained as slender spindles, canopy volume increased gradually year after year, but we did not measure this parameter. Every year crop load levels gradually increased according to the annual increase of trees (TCSA). Every year we were selecting similarly growing (and similarly flowering) trees for crop load studies. In the M&M section we added following information (line 83): 'Each year, similarly growing trees were selected for the studies'.
Comment 6. Figure 3 and 4 should revise and add y-axis. Where is 2022 fruit growth dynamic?
Response 6. Thank you for your remark. ''mm'' added on Y-axis. Sorry, we we did not get reliable results of fruit growth in 2022 due to loss of significant part of marked fruits. Following explanation is provided in M&M: 'Due to the severe drop of marked fruits (due to mechanical or insect damage), fruit size recording was terminated in 2022.'
Comment 7. Reviewer anticipate that authors should add a standard fruit size group.
Response 7. Standard fruit size (class 1) in Norway is from 60 up to 85 mm (up to 90 mm for some large fruited cultivars). This information is added at the beginning of sub-chapter 3.4. Fruit size.
Comment 8. Figure 6 is ambiguous. Authors should revise it.
Response 8. Thank you for the remark. We made corrections according other reviewers suggestions.
Comment 9. Lines 223-229 should revise with specific figure. These figures are ambiguous and don't contrast with other figures.
Response 9. Figure 8 represents usual Correlation chart. For easier understanding years of investigation were provided in the text.
Comment 10. Discussion. Authors should revise more on this section. for example, authors did not explain how fruit thinning and TCSA impact on leaf area and photosynthesis that are interrelated to reblooming and fruit size. Authors should discuss how fruit tree age correlate reblooming and fruit size.
Response 10. Thank you for your suggestions. Sorry to say, we did not conducted physiological studies and such parameters were not recorded. So, we have no such data to explain our results. We concentrated our research and accordingly to it, our discussions on crop load effects on return bloom, pre- and post- harvest fruit quality parameters, fruit growth dynamics or ripening indicators. Some physiological aspects were mentioned in the text. Additional text was added: ''Campbell and Kalcsits [30] in their review indicated two main theories explaining biennial bearing: phytohormone signaling, and resource competition for nutrients and carbohydrates. Though more knowledge on carbohydrate and hormone cycling/signaling are gained, still impact of crop load on return bloom is poorly understood.''
Comment 11. Authors should revise conclusion with objectives.
Response 11. Our main objective was establishment of optimal crop load levels. These findings are provided in the conclusions. During our studies impact of crop load on other important tree and fruit characteristics was established as well and these findings are also included in the conclusions. We edited conclusion section by moving the main finding to the end.
Comment 12. Need English correction.
Response 12. Some corrections were made according to the suggestions of other reviewers.
