Effect of Harvest Frequency, Seed Extraction Time Point and Post-Harvest Cooling on Organic Tomato Seed Production
Round 1
Reviewer 1 Report
The authors investigated the effect of harvest frequency, seed extraction time point and 2 post-harvest cooling on organic tomato seed production. The result will provide valuable information for tomato seed production. However the manuscript draw the conclusion based on the data in only one environment in one year. The authors should gave more data to draw the conclusion.
Author Response
Dear Reviewer,
Thank you very much for your review. The experiment was actually carried out in two consecutive years, but blossom end rot and the complexity of the seed extraction process caused a lot of irregularities, leading to an incomplete data set in 2019. After consultation with a statistician, we decided to exclude the data set due to too many missing data points.
However, in 2019 we did not see any difference between the two different harvesting regimes. Comparing the cool-storage treatment “freq 1 cooled” of G1 and G2 with the non-cooled treatments freq 1 and freq 2, we did not observe any negative effect on germination rate.
As suggested by you, we would like to show the data of 2019 experiment, but due to the reasons explained above, not in a combined analysis with the data from 2020. Therefore, we added a section in materials and methods to explain the situation and added information for 2019 in the supplemental material. We furthermore revised the discussion and conclusion sections. Please find the revised version of the manuscript in the attachment.
Kind regards,
Patricia Schwitter in behalf of all the authors
Reviewer 2 Report
The manuscript is interesting, but the description of the results must be corrected at every stage. First of all, without reading the article to the end, you can get lost in the description of analyzes and the adopted concepts of the analysis.
The initial description of the experiment does not provide clear information on how to deal with freq1. It is not clear which part of the material was cooled and which was not. Based on the paragraph "For genotype 1 and genotype 2 fruits of regularly harvested plants (freq 1) have been collected and cool stored at 7-8 ° C until the next extraction date…." I conclude that all material for genotypes 1 and 2 was "collected and cool stored". If this is the case, it is illegal to draw conclusions about the effects of collecting and cooling on the observed variables. You compare different genotypes treated differently. Where can I find the results of the comparison of genotypes 1 and 2 cooled and not (before paragraph 3.4)? Thus, it should be precisely indicated at which stages of statistical inference this factor is included in the analyzes. For example, are freq 1 and freq 1-cooled combined in the G1 and G2 yield results?
Also, was there an interaction for freq and G?
Do the conclusions in paragraph 3.3 apply to the average yield for all genotypes?
Conclusions drawn without such clarity seem unfounded.
Author Response
Dear reviewer,
Thank you very much for your revision and comments. We agree that some passages are unclearly worded, and we tried to improve them as following:
“2.3. Experimental set-up
…
We applied two different harvesting regimes: In freq 1, mature fruits were regularly harvested twice a week, counted, weighed and afterwards discarded (G3 -G8) or cool stored at 3°C (G1 and G2). After three weeks, seeds from mature fruits harvested on extraction day (G1-G8) and from accumulated cooled fruits were extracted (G1 and G2). In freq 2, fruits with a mixed ripe maturity level were harvested after three weeks on extraction day only, counted, weighed and seeds were extracted (Figure S3). Extractions took place every three weeks and in total three times.
For seed yield extrapolation of “freq 1 cooled”, fruit yield of freq 1 of the corresponding genotype was used. In the results we treat the comparison of harvest frequencies (freq 1, freq 2), extraction time point for genotypes G1-G8 separately from the comparison of the cool storage (harvest frequencies: freq 1, freq 2, freq 1 cooled; extraction time points) of G1 and G2.”
- If this is the case, it is illegal to draw conclusions about the effects of collecting and cooling on the observed variables. You compare different genotypes treated differently. Where can I find the results of the comparison of genotypes 1 and 2 cooled and not (before paragraph 3.4)? Thus, it should be precisely indicated at which stages of statistical inference this factor is included in the analyzes. For example, are freq 1 and freq 1-cooled combined in the G1 and G2 yield results?
A: Given the specification above we hope that it is now clear, that we did not directly compare the variables. We do compare freq 1 and freq 2 on all genotypes – and freq 1, freq 1 cooled and freq 2 for G1 and G2. That is the reason, why the topic “cool storage” is not treated before paragraph 3.4 – because plants and fruit yield of “freq 1” and “freq 1 cooled” of the corresponding genotype are the same.
- Also, was there an interaction for freq and G?
A: We did not find any interaction for harvest frequency and genotype on total yield, thousand seed weight and seed yield, but a significant interaction (p<0.01) on marketable yield for G1, G3 and G6. For the share of rejected yield we did not see this interaction.
We have added the interaction for marketable yield and the share of rejects in the corresponding paragraph 3.2.
-Do the conclusions in paragraph 3.3 apply to the average yield for all genotypes?
A: Yes, except Genotype 7, because data for freq 2 at extraction 3 is missing.
We appreciate your detailed comments and hope that our improvements meet your demands. We furthermore revised the discussion and conclusion sections. Please find the revised manuscript in the attachment.
Kind regards,
Patricia Schwitter in behalf of all the authors
Reviewer 3 Report
Dear authors,
The subject of this publication is interesting and valuable for organic seed producers. However, below are some comments that should be addressed:
- Introduction - it was well written taking into account the current state of knowledge on the topic under study
- Materials and methods - soil data are missing
- L 149 - please provide the type and manufacturer of the seed-counting machine
- Results - have been correctly presented
- Discussion - Although the discussion explains the phenomena obtained as a result of the research, it compares them to a very limited extent with the results of research by other authors. They should be backed up with proper references
- Conclusion - should be written as a separate chapter. I suggest in line 365 not to use the phrase "We hope ...", but to write factual information where the obtained results may apply.
Author Response
Dear reviewer,
Thank you very much for your comments and thoughts. Information about soil data and seed counting machine have been added. In addition, we have revised the discussion section. We further developed the discussion and placed our research in relation to previously conducted research in the field. Below we answer directly to your concerns:
- Materials and methods - soil data are missing – has been added
- L 149 - please provide the type and manufacturer of the seed-counting machine – has been added
- Discussion - Although the discussion explains the phenomena obtained as a result of the research, it compares them to a very limited extent with the results of research by other authors. They should be backed up with proper references
A: Thank you very much for your input. We further developed the discussion and placed our research in relation to previously conducted research in the field.
- Conclusion - should be written as a separate chapter. I suggest in line 365 not to use the phrase "We hope ...", but to write factual information where the obtained results may apply.
A: We added a separate chapter for the conclusions and considered your suggestion.
We appreciate your detailed comments and hope that our improvements meet your demands. Please find a revised version of the manuscript in the attachment.
Kind regards,
Patricia Schwitter on behalf of all the authors
Reviewer 4 Report
Reviewer
MDPI - Sustainability
Manuscript Number: sustainability-1820605
Title: «Effect of harvest frequency, seed extraction time point and post-harvest cooling on organic tomato seed production».
This article touches on an important topic in the modern world. The results may support seed producers in their organic seed propagation strategy and therefore help meet the growing demand for seeds for the organic market.
Author Response
Dear reviewer
Thank you very much for revising our manuscript. We appreciate your comments and are happy, that you share our view that seed production is an important topic in organic agriculture.
We revised the material and methods section, as well as the discussion and conclusion sections. Please find the revised version of the manuscript in the attachment.
Kind regards,
Patricia Schwitter on behalf of all the authors
Round 2
Reviewer 1 Report
Although the experiment were conducted in two environments, the result in the first environment can not provide enough information. So Valid information in more than one environments is needed in the result section to draw the conclusion.
Author Response
Dear Reviewer,
Thank you very much for your input.
We have now improved the text overall.
We have also added information on the trial of 2019 in the material and methods, section 2.3 and results in sections 3.2 (also shown in figure S1 in the supplementary material) and 3.3 (also shown in figure S2 in the supplementary material). We also mentioned when the results were linked only to the data set of 2020.
In section 2.3:
Seeds from the eight genotypes were sown into growing trays on March 19th 2019 and March 11th 2020 and transplanted to 13 cm pots after three weeks in 2019 and two weeks in 2020. Seedlings were planted under the polytunnel 8 weeks and 7 weeks after seeding in 2019 and 2020, respectively. Harvest started for both years in July, 10 weeks after planting (WAP) and ended in September (20 WAP) after the last seed extraction.
In section 3.2:
Throughout the 2020 harvest season, regularly harvested plants (freq 1) produced on average 25% more marketable yield than plants harvested every three weeks (freq 2) (p<0.001, Fig. 2). The same trend was observed in the fruit yield of 2019 (Fig. S1 in supplementary material). Consequently, first quality fruit yield was significantly lower under harvest regime of freq 2, ranging from 3-62% depending on genotype (Tab. 2). A significant interaction on genotype and harvest frequency was observed for marketable fruit yield of G1, G3 and G6 (p<0.01). The share of rejected yield was on average 12% lower under frequently harvested plants (freq 1), with high variation among genotypes (Tab. 1). Similar to the observed interaction of marketable fruit yield, share of rejected yield was significantly higher for freq 2 in G1, G3 and G6 (p<0.05). The reason for rejection was mostly due to bursting of fruits or blossom end rot and therefore might be due to the different irrigation needs of genotypes. Since blossom end rot is mainly due to inadequate irrigation, further results are based on total fruit yield in order not to jeopardize varieties whose irrigation needs could not be individually satisfied and therefore burst or experienced blossom end rot. Harvest frequency had a significant effect on total fruit yield (p<0.05), with more yield harvested under frequency 1. Total fruit yield differed among Genotypes, with G5 and G7 producing significantly more yield than G8 (p<0.05). In 2019, the proportion of rejects was very high, and similarly to 2020, generally higher under the freq 2 regime (Fig. S1)
In section 3.3:
In 2019, the extraction time point had a significant effect on thousand-seed weight (p<0.001). Interaction is observed at the first extraction, where a significantly higher thousand-seed weight is obtained in the freq 2 regime (Fig. S2A in the supplementary material). The extraction date and harvesting treatment had an effect on seed yield (p<0.001 and p=0.084, respectively; Fig. S2B). Harvest frequency and extraction time point had an effect on total fruit yield (p=0.176 and p<0.001, respectively; Fig. S2C). Over both seasons, except for the thousand seed weight in the first extraction, there was no difference between freq 1 and freq 2.
In 2019, there was a higher proportion of rejects compared to 2020 due to the susceptibility of several genotypes to Blossom End Rot (BER).
We found otherwise no difference between the harvesting frequencies freq1 and freq 2 in 2019 which supports the conclusions of the 2020 results. Minor differences in fruit yield were observed in 2019, mainly due to the excessive losses related to BER.
Data of both years are in line and support the main conclusions that “harvest of tomato fruits for seed production can be i) regularly done and fruits stored for a pooled extraction or ii) harvested every three weeks and extracted after exclusion of infected fruits. These results can support small and larger seed producers in their strategy to multiply seeds under organic conditions.”
We hope that these amendments show that the main conclusions are indeed based on 2 environments and are therefore significant.
Many thanks and best regards,
Joelle Herforth-Rahmé on behalf of all three authors
Reviewer 3 Report
Dear authors,
The manuscript has been greatly improved as suggested. I recommend a work for publication.
Author Response
Dear reviewer,
Thank you very much for your comment and recommendation of our work for publication. We are happy that you are satisfied with the improved version.
Best regards,
Joelle Herforth on behalf of the authors
