What is the best light source to use?

The purpose of this experiment is to demonstrate the value of various lights in relation to pinning duration's and fruiting.

Types of lighting used:

100 watt High Pressure Sodium (HPS)
100 watt Metal Halide (MH)
100 watt incandescent Gro-Light
28 watt fluorescent
28 watt fluorescent ultra violet

The fluorescents are of a lower wattage, but remain at the industry standard for lumen comparison with incandescent.

The temperature was kept at a constant 77 degrees and humidity maintained at 95br>
Usable light energy for plant growth is measured in Micro-Einsteins which are micro-mols of photons per meter squared per second.

To maintain consistency during this experiment, the distance between light source and material was maintained at 300 Micro-Einsteins as measured by a borrowed Quantum reader. 300 Micro-Einsteins was chosen as this is the industry standard minimum for indoor plant growth.

10 half pint jars were prepared and inoculated. 3 cups vermiculite. 2 cups brown rice flower. 3 cups water.

Koh Samui was chosen for this experiment because it was readily available and quick colonization. This is my regular spore of choice for experimentation as I'm familiar with its growth characteristics.

All jars were inoculated at the same time from the same syringe using the same spore print. Cakes were chosen to maintain consistency and for easy viewing of pins.

Two jars each were used for each light source in the event of contamination.

The growing area was divided and each sampling was placed in a separate light proof area. Each light source was timer controlled and set to activate one hour every six hours for a total of four daily hours.

A brief description of each will be followed by the results and commentary.

100 watt High Pressure Sodium (HPS) - HPS lights are a brighter full range light with spectrums of white, blue, red and orange. Red and orange are most desirable for fruiting (or budding) plants using photosynthesis. The only problem associated with this light source was the intense heat associated with it. To maintain 300 Micro-Einsteins, a distance of 4.2 feet was necessary. To maintain 77 degrees, the exhaust fans were left on throughout the process and additional air-conditioning was used.

100 watt Metal Halide (MH) - MH lights are rich in white and blue spectrums desirable during vegetation of plants using photosynthesis. Heat was also a negative factor with the MH lamp and a distance of 3.8 feet was necessary to maintain 300 Micro-Einsteins. Again, constant exhaust fanning and AC was needed.

100 watt incandescent Gro-Light - Incandescent Gro Lights produce light spectrums of white, blue, red and orange. All spectrums necessary for vegetative growth and fruiting, but do so in tiny amounts. To maintain 300 Micro-Einsteins, a distance of 4 inches was necessary. A smaller fan was used to dissipate heat.

28 watt fluorescent Gro-Light - The light spectrum was almost identical to the incandescent, with slightly more white light which would benefit photosensitive plants during their vegetative state. The problem associated with this light source was the low lumen output. A distance of 1 inch was needed to maintain 300 Micro-Einsteins. At this distance, temperature was not of a negative issue because of the fluorescents efficiency.

28 watt fluorescent ultra violet - This was a true ultraviolet light source, not the "black light" bulb. Micro-Einsteins for this light source were measured at . 025. Maintaining the Micro-Einsteins minimum of 300 was not possible, but the bulb was still used and placed as close to the birthed cake as possible without touching. Less than a quarter inch.

My original hypothesis was that the lumen intensity of the HPS and MH would induce faster pinning, but was demonstrated wrong.

With the exception of the ultraviolet lamp, each of the remaining four light sources had near identical pin growth, timing and fruit completion. Pins for each were plus or minus 4.

Each pinned within 24 hours of the others with the fluorescent pinning first followed by the MH, incandescent and HPS.

The ultraviolet lamp slowed pinning and stunted carpophore growth.

For green plants that require photosynthesis an incandescent or fluorescent Gro-Light would work well with germination and seedling stages, but the low lumen output would create stretching of vegetative green plants as they grew taller in an attempt to gather more light.

For green plants using photosynthesis, they thrive with white and blue spectrums. A MH would serve this purpose well and would also produce acceptable lumens to reduce plant stretching. Fruiting green plants would thrive with a spectrum of red and orange. For this reason, switching to a HPS or supplementing with an HPS during fruiting of green plants would benefit most.

My findings for this experiment was that no light source had advantage over another in pinning or fruiting. Additionally, there were no noticeable differences in potency or yield.

I've been using a weak 50 watt incandescent bulb set to activate for one hour every six hours for a total of four hours daily. After my demonstrated results I will continue to do so as there is no advantage given to any tested light source.

by Ainasko

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OK, I know there have been previous discussions about lighting. I think it's Paul Stamets Mushroom Cultivator book states simply that blue and UV are the best.
A fellow member also did some experimenting with various bulbs and it's pretty interesting. It can be read here, https://www.shroomery.org/forums/showflat.php/Number/1572090. Thank you to Ainasko for your great work.

A couple of people have asked me about the more "detailed/technical" aspects of how mushrooms and light interact. They are photoreceptive, and positively phototropic from what I have read here and elsewhere. I've done some more research though, so to really figure out how this all works. It turns out it is a combination of factors. Thanks to "ThePyschonaut52" for posing the initial questions that started this endeavour.
Read on if you dare, this is gonna get a little intense.

To answer the initial question "what type/spectrum of light is best for initiating fruiting", I will repeat what others have said, only referring to a 1980 study which used various lights, intensities and durations (they called them 'doses' haha)

E. R. Badham. "The Effect of Light upon Basidiocarp Initiation in Psilocybe cubensis" Mycologia, Vol. 72, No. 1. (Jan. - Feb., 1980), pp. 136-142.

I will quote directly from this article and then comments follow each quotation where I have wished to clarify or expand.

"Two preliminary experiments were conducted to determine : 1) the general wavelengths of importance for fruit body initiation, and 2) the duration of light necessary for initiation."

"Spectral sensitivity peaked in the blue and UV, No light of wavelengths greater than 525 nnl was photo inductive."

"UV-illuminated cultures formed fruit body initials. When other cultures were illuminated with one 0.0005-sec flash/day for 5 days initials were present on the 6th day."

"The low level of light necessary for initiation of basidiocarps in Psilocybe cubensis is in agreement with the requirements of other Basidiomycetes that have been studied."

"Spectral-sensitivity studies show that at least two areas of the spectrum stimulate fruit body initiation, the blue and the UV. This is characteristic for many photo responses of fungi."

"Briggs (1976) suggested that the blue-light reactions in green plants and fungi are similar. If this is so then many of the known blue-light mediated effects in green plants need to be reviewed for fungi. Of particular concern to this study is the connection between blue-light reactions and red-light reactions (phytochrome system) demonstrated by Chon and Briggs (1966). Since red light did not initiate fruitbodies it was considered appropriate as a "safe" light. This may be an incorrect assumption. Finally, although development after initiation seems to require light, it is not known if the action spectrum required is similar to that needed for initiation of basidiocarps."
-the last sentence interests me because it acknowledges that light is required for fruiting initiation, but also that light is required throughout the fruiting, however it is not known if it should be in the same spectrum as that which initiates fruiting. This is where we need to do the most research I think, now that we've established UV and blue initiate pinning. Note: "Diploid" states in a later thread that the use of UV light leads to genetic damage down the road.
https://www.shroomery.org/forums/showflat.php/Number/1702007

And now, onto the really intense stuff about how the mushroom actually 'receives' and interacts with light.
This is taken from: Lu, B. "The Role of Light in Fructification of the Basidiomycete Cyathus stercoreus." American Journal of Botany. Vol. 52, No. 5 (May, 1965), pp. 432-437.
It is quite an old study, but it establishes the basics for what is to come in later research.

"It is hypothesized that photoinduction becomes operative when a hypothetical 'photoreceptive precursor' develops. The development of such a precursor is believed to occur when conditions unfavorable for good vegetative growth (e.g. shortage of food supply, [or temperature change?]) develop in the culture. Internal metabolic pathways then shift to favor the production of the photoreceptive precursor"

Now, this article gets into genetics a little bit. It also suggests that mushrooms, like plants and animals, are subject to circadian rhythms (the natural outdoor light cycle our bodies are accustomed to), as well as other light sources. The last article and this article are both talking about different types of fungi, however I will make an argument in the end that this is irrelevant and these photoreceptive systems are common to all fungi.
J.J. Loros, J.C. Dunlap. "Circadian Rhythms, Photobiology and Functional Genomics in Neurospora."

"The ability of fungi to sense light using photoreceptive molecules is also common to most or all cells of the organism. The molecular basis of light sensing has also been the focus of intense study, now yielding to the combination of classic genetic and modern molecular, biochemical and genomic techniques. Indeed, the well-known interplay between daily rhythms and light sensing turned out to have profound interconnections at the molecular level. Many genes regulated by the clock are additionally regulated by light. The FREQUENCY (FRQ) protein is the central negative element in the autoregulatory feedback at the core of the circadian clock in Neurospora. White-collar-1 (WC-1), part of the heterodimeric transcription factor with white-collar-2 (WC-2) that drives FRQ expression and is thereby a central component of the clock feedback mechanism, is also the photoreceptor for the circadian clock, as well as all other blue light-regulated genes in Neurospora."

-notice "the combination of classic genetic and modern molecular, biochemical and genomic techniques". It is a combination of factors.

I found this next bit of information just on a Google search, but it was relevant and informative and it reaffirms the above statements.
fungi « WordPress.com Tag Feed, http://wordpress.com/tag/fungi/feed/

"We know light sensins is controlled in part by the gene white-collar 1. A homolog of this gene in Neurospora crassa is involved as an oscillator circadian rhythm. Of course many more genes are involve in pathways for light sensing including some really old proteins like phytochromes."

Finally, this next quotation is basically my argument that it is irrelevant that the above articles are about other species of fungi. It is from the abstract (just to make things simple) of this article, which I believe is available online for free since it's under Creative Commons licensing (which is awesome if you don't mind me saying so): Alexander Idnurm, Joseph Heitman. "Light Controls Growth and Development via a Conserved Pathway in the Fungal Kingdom." PLoS Biol 3(4): e95 doi:10.1371/journal.pbio.0030095.

"These results demonstrate that a role for blue/UV light in controlling development is an ancient process that predates the divergence of the fungi into the ascomycete and basidiomycete [i.e. all fungi with gills and spores, e.g. our friends p. cubensis] phyla."
-This statement justifies attributing the same genes, proteins and "photoreceptors" and possibly phytochromes (that are in plants, and as has already been mentioned above, plants and fungi may have quite similar processes [remember Briggs (1976) cited in Badham's article]) are at work in all fungi, psilocybe cubensis, cyanescens, etc. included. That is, unless they have evolved AWAY from these mechanisms, but I see this to be highly unlikely.


So, there you have it. All I can do is call for someone to look into not what spectrums are good for initiating fruiting, but what spectrums are best during fruiting. I'm going to hypothesize that it's UV and blue as well though (just like natural light).
Hopefully you're all still awake and your eyes haven't fallen out of your heads by now.

by aberrant