Hello, I had said I would do an unofficial test during this grow on two DP Auto Blueberry that are now ready. It is simply by isolating one plant and exposing part of it to a small 15w reptile bulb for 6 hours a day, while the other girl is not. If it helps potency, I should see it in two forms. From plant to plant, and from exposed buds to non exposed buds of the same plant.
I don't propose that this will answer the question of UVB benefits definitively but it can't hurt.
Feenix--excellent controlled test.
About a year ago, bought three of the reptilian CFL's must be around 15 to 25 watts. Only a portion is UVB the other if visible light likely blue (guessing--will check when wear my yellow lenses which blocks "blue" light like magic and purportedly help with sleep--they work well with LED too--inexpensive see Amazon less than 10 bucks).
Anyway, after reading Rosenthal's book this is what he said: In California many dispensaries reject late season ripened medical grade canna--per strength and assume over all low quality. This is due to lack of UVB as a ripening agent of sorts. They opt for indoor grown which does have a bit of UVB--but not much. Artificial light intensity likely makes up for it.
He shows how, outside, one can sow early in spring then cover plants for dark period and open up early Summer for high point of UVB.
exposure. The plants get the 12 hours of darkness by tarp cover and then are exposed to high UVB during flowering.
The above cannabis is sough out by dispensaries as being super. Supposed primo bud!
There was a study done by a grad student and published showing dramatic effects with UVB exposure.
This study and Rosenthal's take is online and in his book.
Indoors--Rosenthal recommends 10% UBV bulbs per 100 watts so 100 watts per 1000 watt grow lamps (I will double check--and it is correct)/regular light. Using reptile bulbs or suntanning lamps. So a 300 watt LED one would use--30 watts of UVB supplementation light.
I have used then haphazardly. Sometimes to help a plant that looks like it is stalled and others nearing early mid-ripening.
However, I have not taken time to compare, so, your study will be excellent.
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Only 10% of UVB lamps product the UBV, like mentioned above, the rest is visible light. Still it is the UBV bulb output that counts towards the supplementation--not the 10% thereof.
I like your approach to testing phenos and a branch for comparison.
Supposedly the plant increases it production of UVB blocking chems which are the trichs. Suntan lotion for the flower/leaves. I have not had any burn with some bulbs right on top of buds. They do need to be fairly close guessing six inches to just a few if honing in on one bud/limb.
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My plants are multi-strained and multi pheno on a couple. A few coming up for harvest next week had the UBV for three to four weeks each. Other plants may have picked up a bit with reflectors. Interestingly most of my plants are heavy trich inside and on bud surface--not much shooting out to fan leaves. Looking with loup can see leaves are coated in areas without capitate trichs.
Right now, three reflectors are point at one Herajuna J33. Supposedly a quick ripener. Not this one, it is two weeks away from others, but rapidly catching up. Have also reduced lighting to 14--off/10--on to hasten ripening (Rosenthal once again). Photos do their busy flowering during dark period. Release energy and the chemical processing takes place. That is why a dark period with photos is so important--when the plants quietly do their flowering and ripening. Autos--prefer light and not so much darkness for they have their flowering hormone "on" 24/7 regardless of light schedule. My recent 12/12 resulted in smaller plant and airy buds.
The timing is just right on this plant for it has about two weeks to ripen and is quickly drying out its pistils. Little trichs outside of the flowers. Appears to be Indica in structure with buds like sativa with most trichs internal to the buds. What a great unusual aroma when pinched--like a kitchen full of spice. One of the most complex aromas I have sampled--like an expensive bottle of perfume.
I will keep you posted on this plant. Remind me in a few weeks--if I forget.
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One of our senior members (DUBV) discussed such sometime back and was not concerned with length of time using UVB during daily session. Like you I am thinking 6 hours to mimic nature (I assume high mark in sun UVB is about that amount of time).
Cheers
