Effect of Nutrient Solution Cooling in Summer and Heating in Winter on the Performance of Baby Leafy Vegetables in Deep-Water Hydroponic Systems
Round 1
Reviewer 1 Report
The authors provide useful information about nutrient solution cooling and heating in deep-water hydroponic systems on the performance of several leafy green vegetables. The MS is well written and generally is a very good descriptive study, and the methodology used to address the objectives is clear and well established in the literature. Just one point, the rate of death of leafy greens under cooling (23°C) and heating (22°C) is a kind of high. Also please note the minor errors, for example, now space between 22 and °C.
Author Response
Review 1
The authors provide useful information about nutrient solution cooling and heating in deep-water hydroponic systems on the performance of several leafy green vegetables. The MS is well written and generally is a very good descriptive study, and the methodology used to address the objectives is clear and well established in the literature. Just one point, the rate of death of leafy greens under cooling (23°C) and heating (22°C) is a kind of high. Also please note the minor errors, for example, now space between 22 and °C.
Our Responses:
Thank you for your comments. In the cooling study in summer, plant death was only observed among spinach plants, indicating that spinach is not suitable for summer production. All other leafy greens can be grown year-round. For the winter heating study, we presented the freeze damage, not mortality rate. Please see Lines 220-223 (The freeze damage of lettuce plants was assessed several days later and calculated as percent of damaged leaves (partial or edge of the leaf) to the total leaf count per plant. However, plants grew out quickly and the freeze damage on some leaves had minimal effect on the study) and also in Lines 371-376 (the last paragraph of the Results section).
As for the space between 22 and °C, I think there should be a space. I I have checked the recent published articles in Horticulturae and they all have a space. I also checked Hortscience and Scientia Horticulturae – same format (with a space). But I am fine to delete the space if the academic editor wants to change. Thanks.
Reviewer 2 Report
I find this manuscript very interesting. Heating in winter and cooling in summer increase the yield of vegetables. This is also supported by production data. However, I still have some suggestions.
Introduction: you need to give clear hypothesis.
Results: if possible, I would like to see some nutrition data, such as the content of total nitrogen, phosphorus, and potassium. In the final analysis, the nutritional value of vegetables is very good if it is not reduced by your method.
It is hoped that the authors will supplement the pictures of this experiment to prove results.
In addition, did the author calculate the amount of electricity? If the power consumption is increased by heating or cooling, is it not worth it? I want to see the relationship between yield and electricity consumption.
In the future, I hope to see more physiological data in this experiment, such as primary nitrogen metabolism, transcriptome / metabolome / proteome
Author Response
Review 2
I find this manuscript very interesting. Heating in winter and cooling in summer increase the yield of vegetables. This is also supported by production data. However, I still have some suggestions.
Response: Thank you for your comments.
Introduction: you need to give clear hypothesis.
Response: We added a hypothesis in the last paragraph of the Introduction.
Results: if possible, I would like to see some nutrition data, such as the content of total nitrogen, phosphorus, and potassium. In the final analysis, the nutritional value of vegetables is very good if it is not reduced by your method.
Response: Thanks for your suggestion. In this study, we did not measure the nutritional data in the cooling study. We did measure several phytochemical data in the heating study. But the effect between treatments was not significant or very small. We decided not to present these data in this paper. We are planning more studies in the future on this topic and will plan to measure more nutritional parameters including mineral contents.
It is hoped that the authors will supplement the pictures of this experiment to prove results.
Response: Thanks for your suggestions. Since we conducted a total of 4 experiments, we decided to present all the growth and physiological response data instead of photos.
In addition, did the author calculate the amount of electricity? If the power consumption is increased by heating or cooling, is it not worth it? I want to see the relationship between yield and electricity consumption.
Response: Thanks for your great suggestion. Unfortunately, we did not have the electricity data.
In the future, I hope to see more physiological data in this experiment, such as primary nitrogen metabolism, transcriptome / metabolome / proteome
Response: Thanks for your great suggestions. We are planning for more nutritional data. However, our lab is not equipped for data like transcriptome/ metabolome / proteome.
Reviewer 3 Report
An economic approach of the heating/cooling nutrient solution would be of great interest for practice. Even so the paper is interesting and brings new information on controlling the nutrient solution temperature of hydroponic leafy green vegetable production.
Author Response
An economic approach of the heating/cooling nutrient solution would be of great interest for practice. Even so the paper is interesting and brings new information on controlling the nutrient solution temperature of hydroponic leafy green vegetable production.
Response: Thank you for the suggestion and comments. We will record the electricity consumption and collaborate with economists to conduct a feasibility study in our future studies.
Reviewer 4 Report
Well done, few remarks follow my comments
Comments for author File: 
Comments.pdf
Author Response
Well done, few remarks follow my comments
Our Reponses:
Thank you for your comments.
Page 2: we used pelleted seeds (added this information in the text)
Page 3:
- as suggested, we changed the term “trial” to experiment throughout the paper. (trial = experiment; Trial 1 = Expt. 1; Trial 2 = Expt. 2)
- Cooling and heating solution temperature set was constant for both day and night (added in the materials and method section)
Page 6: added in figure caption: All growth data from C to H are g/plant. Also revised the caption of Figure 4.
Page 7: SPAD is dimensionless.
