Can I have a distinct point of view?

[Ray]

That spectrum is a little lacking in red, but looks pretty good overall!

[Nexogen]

Originally Posted by Ray

That spectrum is a little lacking in red, but looks pretty good overall!

Unfortunately, we both wrote at the same time.

[naoki]

Originally Posted by Ray

I agree that spectrum is important, and I put a lot of faith in Naoki's suggestions, but think he leaves the spectrum out of his considerations at times. However, I also think you may be making some rather arbitrary assumptions.

Just to make sure, there is no doubt that plants respond differently to different spectra. This response of photo-morphogenesis is quite dependent on the species (not surprising if you consider they have adapted to many different types of environments). However, I haven't seen enough scientific data in orchids to say a lot of things. There are a few studies. Higher R:FR has induced spiking more frequently in Phalaenopsis (Lu et al. 2016, American Journal of Plant Sciences 7:639-648). But the effect of additional blue or red on the photosynthesis wasn't significant (they controlled the PPF to be similar). I lost the citation, but with Phal, increased blue increased the production of chemicals used as defense.

Also, with crop plants which have been studied more, people aren't trying to come up with a single best spectrum. Those people are trying to understand how to use modification of spectra to improve the product quality. So different light spectra are needed for the different life stage (e.g. seedling stage vs flowering stage) and different goals (more yield, tastier vegetables, vegetables good for human health etc).

With regard to photosynthesis, it is a bit easier, but then we have to assume that McCree curve is applicable to orchids (a big assumption as we discussed before). You can calculate the approximate amount of light useful for photosynthesis, either photosynthetic photon flux (PPF) or yield photo flux (YPF), for different color (K) and CRI. With modern LED phosphor, high CRI ones became quite efficient, so the gap between low vs high CRI became quite small.

[Nexogen]

In case of orchids it is quite difficult to know at what stage it is (if you have a collection of different species) you can know this only if you grow same type of plant, I grow orchids in house and I want to have a quality light for plants and for human eye, that is why I use a spectrum controlled (approximately) by me.

I do not have horticultural studies, I'm an electronic engineer. I did the experiments based on this curve and the plant response and I've read many comments about the influence of light on plant growth.

[Nexogen]

A spectrum of COB Citizen 4000K + 3500K + etc at the same power consumed (approximately 52 W) make bloom all cattleyas.

[Nexogen]

Who grows orchids in the terrarium or shelf - rack and wants a good light can do it yourself. Now I do not have time but I'll show you later some LED grow lights built by me. I used some old lights with T5 HO from which I dismantled everything and applied heatsink with Kafuter-silicone thermal adhesive. You can choose for your own application, for example; if you use a shelf, you can mount heatsink directly to the rack. DIY LED grow light is very simple, it's more difficult to accept that you can do it. I'm going to show you my construction method that does not involve holes: Heatsink big size (temperature is the greatest enemy of electronic components, in special to LED grow light - it also provides physical support, so you do not have to build anything extra), white COB LEDs and XXXnm LEDs (for XXXnm LED you can use the table below) important for the orchids, thermal adhesive (preferable Arctic Silver thermal adhesive), holders and reflectors for COBs, driver for LEDs, thermal protection circuit, 12V fans and 9V power supply for fans and thermal protection circuit (if the device that produces the light is in the house where we live we do not need too much fan noise, so I've chosen NF-P14s Redux fans - powered at 9V).

[Nexogen]

PS: I can not take pictures now because my wife kills me, I'm hardly tolerated to grow orchids in the house, that's why I opted for the best light for human eyes and orchids and low noise.

[Nexogen]

Finally, I managed to take some pictures.

Temperature on the heatsink surface is two degrees C over ambient, I have provided thermal protection if it exceeds 45 degrees C, in extreme cases.
In this case I used two fans on the top, I could only use one but I was a little "snob".

[Nexogen]

I know, you're going to say it's not a good way to use Arctic Silver thermal adhesive because if you want to make changes you cannot disassemble anything.
You are wrong, with a cutter blade or pliers I unzipped the chip after which I used Goof off and sandpaper 800 grit, within one minute I cleaned a 60 cm long heatsink.

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I am not an English speaker and I use Google Translate. I have seen that it does not translate well and some phrases are mistakenly grammatical, even the words are wrong and vulgar. In any case, I do not consume hallucinogens or alcohol.