weedtech
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Interesting read I found here.
An Update on Plant Photobiology and Implications for Cannabis Production
This video talks about the topics in this thread (nutrient use) Toward an Optimal Spectral Quality for Plant Growth and Development
@Kanzeon Welcome to the farm. I see you took the red pill.
If you parse the video carefully - you may note that Far-red spectrum is useful at flip ( 12 hour regimen ) to stimulate early, robust flowering. I would suspect this may be the Fall light spectrum ( recall, we want to mimick the normal solar exposure, low angle sun ) that assists in triggering the natural ripening process.
I've been looking at this spectrum issue ever since the emergence of LED light sources for growing. I've worked with LED and other light source technologies since the 80's. My biggest frustration has been with looking at static spectrum charts rather than actual spectrum data from MY light sources. Light sources age, degrade and shift from the first time power is applied and I can assure you that any source spectrum the vendor shares is probably not what the source provides over the expected service life of the source. Lab-quality instrumentation for measuring spectrum is expensive, even as used equipment.
Fortunately, the germans have been really busy working on devices that solved most of the problems, including cost. I built a prototype based on the hardware and some open-source code that gives me the data I wanted - in a easily consumable format. I'll share the output in my next post.
Do they tend to have a narrower spectrum over time?
THIS is why we have the farm - to compare notes and observations. It's pretty much:
View attachment 925179
Am I missing anything?
I don't know if you have looked at the other research done around the edges of standard PAR spectrum, Dr. Bugbee has been looking at far IR effects and has only noted the stretch effects of blue light. I've been experimenting with UVA and UVB source augmentation. I had been using high output UV lamps for reptiles and had good results. I have some new lamps to test with some new information on exposure periods.
These are my test subjects, Platinum Zkittles and Lemongrass.View attachment 969660
Exactly. Plus the growers here aren't shy about offering constructive criticism, which is awesome.
To this end, my next light purchase is almost definitely going to be E27 COB bulbs ranging from 2700k to 4000k.
Something along THESE lines.
So Bruce Bugbee himself recommends about 1000 PPFD for indoor cannabis plants. That's the end goal. That dude knows his shit.
The design of quantum boards is awesome for a lot of things, but they distribute light in one general direction- down. My canopy isn't and won't be even (I'm too much of a tinkerer and like to grow a bunch of different strains), so a level light source above the plants means that the top buds get the majority of the full-spectrum light, which then degrades in quality as it bounces around the space.
My theory at the moment is that a number of smaller LED bulbs placed above the perimeter of the general canopy and directed at intersecting angles across the grow space could potentially be a more efficient solution in terms of both electricity and yield than adding another quantum board. More light = bigger buds, right? With the lights at an angle, the photons coming from them can theoretically be used by the plant to greater effect since they're exposed to more of the plant's surface area without hitting anything else.
Those lights above claim 700 lumens per 15w led bulb (5 diodes per), but they don't say at what distance that was measured from. When putting them up, I'll measure so that they're roughly 70,000 lux (where the risk of light shock rises) to the canopy, but mounted at 45-60 degree angles, which works out to roughly 1000-1200 PPFD with the estimated combined bulb spectrums.
Am I missing anything?
I'm going to change the exposure regimen as well. Some new research I've been following shows that constant UV exposure tends to harden the plant to further exposure and diminished results tend to be the outcome. I'm going to try a bracketed exposure around what would be solar noon. 2 hours before, two after with a two hour buffer centered on midday. What I'm after is enhanced turpine profiles and potency. I've seen good effect when used during flower and early on to keep the stretch on some strains from getting excessive.
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