Quantifying the Effect of Light Intensity Uniformity on the Crop Yield by Pea Microgreens Growth Experiments

Round 1

Reviewer 1 Report

Dear authors,

You are addressing an interesting question in this paper but in order for me to understand fully what you have been doing I need first some clarifications before I can further assess the work.

Here are the few comments I have so far and would propose to continue after those are implemented such that I can better understand what you have been doing and the experimental conditions of the trial.

Please indicate the relative humidity as well in the room and the presence or absence of CO2 as well as airflow or dehumidification unit etc…(standards for a vertical farm)

Please indicate the distance between LED emitter/lamp to the top of the fully grown plant. The distance you are indicating 45 and 21cm is the bottom of the plant ? or even lower ? Not sure I understand

143: To be able to read easily, can you please rename your code? It seems that A7 B5 and B6 is not relevant in this and makes the reader confused. Just call them A,B and C.

Line 146: A7, B5 and B6…you wrote twice B5.

Figure 3: I do not understand the side view and why you did not use two trays per layers. I do not understand the denomination LED A-2 and LED A-3 …LED B-2 and LED B-3  as well as the significance of the color coding used. This is very confusing

Line 203: if green starts at 500nm , blue should finish at 499 nm

Line 208: you mention the relevance of R:B and R:Fr ratio in your introduction, maybe good also to mention the values in your spectrum. Easier for the reader to relate to past experiments and compare.

Please indicate the presence or absence of optics in front of the LED. Best would be to disclose in an appendix the luminous emittance diagram of that specific lamp (this is provided by the LED manufacturer).

When varying the height and distance from LED to plant, it is wise to measure the plant temperature. Although LED are known to be a cold light source there is still some radiation effect especially when the lamp is brought closer to the plant (21 cm versus 45 cm). You can feel this already by placing your hand underneath therefore I expect a non negligeable radiative heat effect to the plant locally too. To avoid complex calculation, you can measure plant temperature along x and y as well, which I think is crucial for understanding exactly what is going on with the light distribution. It would be scientifically correct to mention the radiative and thermal aspect of light absorption in this specific case.

Light intensity and temperature are closely linked. 100 umol/m2/s do not perform the same as 400 umol/m2/s if climate set point is kept at 20deg C. One shall expect that 400 umol/m2/s might require a higher climate set point temperature.

Temperature is the main factor making microgreens grow and it could be a more important factor than light or the photosynthetic aspect of it. Only a small fraction of the light energy is used for photosynthesis. Most other growth process are driven because of heat loss of light in the plant, transpiration, respiration and photochemical process. This experiment is well designed to study deeply this aspect which is too often neglected in vertical farming fundamental research.

it is ok

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Editors,

 Manuscript entitled "Quantifying the effect of light intensity uniformity on the crop yield by pea microgreens growth experiments" by László Balázs et al. is within the aim and scope of Horticulturae. The authors presented the effect of spatial photon irradiance variations on the growth traits of pea microgreens in order to optimize commercial microgreens production.

 The study is attractive with interesting subject and good experimental work, offering some interesting results. However, there are a few points of concern and I would recommend reconsideration of this manuscript after supplementations and corrections (attached file).

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks, the manuscript has imporved greatly