UVB Timing

Positivity said:

Very nice..appreciate that.

thats a lot of pluses across the board. It would be nice to be able to achieve that through UVA but as you've noted it brings blue type growth along with it. I broke my 385nm led so I won't be able to try that this round..was doing some troubleshooting and the star didn't like being worked on so much. Thinking of ordering another but the quality on that particular star seemed a little low for the price.


havent noticed a delay in flowering at all from heavy 660. Could be my 730 flower trigger works well. Next run I'll leave it off and see if there's a delay..I'd kinda like to know the answer to that.

Any good UVA led suppliers?

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660 nm deep red + 400 up to 450 nm blue,do delay transition in flowering ...
( Simply a Pf/Pfr imbalance due to 660 nm alone and blue just makes things worse ... )

660 nm + 730 nm leds +blue 400-450 nm = no delay
660 nm + Warm White 2700°K >85CRI + Neutral White 5000°K 80CRI = no delay

Good Uva leds :
Semileds http://www.semileds.com/UVLED_SemiLEDs.htm ( 5$ -20$ on a star )
http://www.rapidled.com/violet-uv-leds/

More 'buyer's' info about UV leds market : http://www.i-micronews.com/upload/Rapports/Yole_UV_LEDs_March_2013_Sample.pdf

MR® 4010 UV-Panel-Light LED-Area lamp ( 45 W/m^2 UVA @365 nm )

http://www.mr-chemie.de/en/products/uv_technology/uv-lights/

http://www.em.avnet.com/en-us/design/marketsolutions/Documents/Lighting/LightSpeed-Eskow-1008.pdf

I'll be looking for leds in the 365 - 385 range. Although I think the range from 405 - 430 is worth looking in to. I have a few in there now and I am curious what would happen if I raised output further. For now I'd like to try the non visible range which should start bringing changes farther from the blue range.

I'll take a look at semileds and see how they compare to ledengin. May have to delay the next run until I can get something in. But at this point I can't see much more being needed spectrum wise. Just be doing a little testing here and there just in case..

Maybe someone can tell me if something like this would work. http://bigbudsmag.com/grow/how/article/get-more-thc-your-medical-marijuana-plants-using-uv-light-august-2012 Here's a little bit of info, hope it is good reading for someone.http://bigbudsmag.com/grow/how/arti...l-marijuana-plants-using-uv-light-august-2012

Here some,more detailed for that someone ...

http://faculty.ksu.edu.sa/18856/Art...mulation of medicinal compounds in plants.pdf


http://www.google.gr/url?sa=t&rct=j...qkSrkwQXV3UsrE3LEvdRhhg&bvm=bv.62922401,d.Yms

The effect of ultraviolet radiation on the accumulation of medicinal compounds in plants.

Wen Jing Zhang, Lars Olof Björn


Department of Cell and Organism Biology, Sölvegatan 35, SE-22362 Lund, Sweden.
Fitoterapia (Impact Factor: 2.23). 03/2009; 80(4):207-18. DOI:10.1016/j.fitote.2009.02.006 Source: PubMed

ABSTRACT A review is given of how the production by plants of compounds useful as medicines or raw materials for manufacture of medicines is influenced by ultraviolet radiation, particularly by UV-B radiation (280-315 nm wavelength). The compounds considered in this review are flavonoids and other phenolics, alkaloids (especially indole terpenoid and purine alkaloids), essential oils and other terpenoids, cannabinoids, glucosinolates and isothiocyanates, and compounds having human hormone activity. A short account is also given of ultraviolet signalling in plants. The review concludes with a discussion of the possible evolutionary mechanisms that have led to the evolution of UV-B regulation of secondary metabolite accumulation.

Plant J. 2012 Aug;71(3):353-65. doi: 10.1111/j.1365-313X.2012.04949.x. Epub 2012 Jun 1.
[h=1]The hexanoyl-CoA precursor for cannabinoid biosynthesis is formed by an acyl-activating enzyme in Cannabis sativa trichomes.[/h]Stout JM[SUP]1[/SUP], Boubakir Z, Ambrose SJ, Purves RW, Page JE.
[h=3]Author information [/h]
[h=3]Abstract[/h]The psychoactive and analgesic cannabinoids (e.g. Δ(9) -tetrahydrocannabinol (THC)) in Cannabis sativa are formed from the short-chain fatty acyl-coenzyme A (CoA) precursor hexanoyl-CoA. Cannabinoids are synthesized in glandular trichomes present mainly on female flowers. We quantified hexanoyl-CoA using LC-MS/MS and found levels of 15.5 pmol g(-1) fresh weight in female hemp flowers with lower amounts in leaves, stems and roots. This pattern parallels the accumulation of the end-product cannabinoid, cannabidiolic acid (CBDA). To search for the acyl-activating enzyme (AAE) that synthesizes hexanoyl-CoA from hexanoate, we analyzed the transcriptome of isolated glandular trichomes. We identified 11 unigenes that encoded putative AAEs including CsAAE1, which shows high transcript abundance in glandular trichomes. In vitro assays showed that recombinant CsAAE1 activates hexanoate and other short- and medium-chained fatty acids. This activity and the trichome-specific expression of CsAAE1 suggest that it is the hexanoyl-CoA synthetase that supplies the cannabinoid pathway. CsAAE3 encodes a peroxisomal enzyme that activates a variety of fatty acid substrates including hexanoate. Although phylogenetic analysis showed that CsAAE1 groups with peroxisomal AAEs, it lacked a peroxisome targeting sequence 1 (PTS1) and localized to the cytoplasm. We suggest that CsAAE1 may have been recruited to the cannabinoid pathway through the loss of its PTS1, thereby redirecting it to the cytoplasm. To probe the origin of hexanoate, we analyzed the trichome expressed sequence tag (EST) dataset for enzymes of fatty acid metabolism. The high abundance of transcripts that encode desaturases and a lipoxygenase suggests that hexanoate may be formed through a pathway that involves the oxygenation and breakdown of unsaturated fatty acids.

© 2012 National Research Council of Canada. The Plant Journal © 2012 Blackwell Publishing Ltd.


Oxygen,oxygen..and short wavelengths ...

Ta-ra-ram.ta-ram.ta-ta ...

^^ I kinda like it too. Having been exposed to high and low elevation herb all my life it became pretty clear the psychoactive differences and even terpene expressions. The missing link..

Well, I put 2-26 watt UVB lizard lamps onto a couple plant's in a closet. They were around 3 week's into bloom when I lit them up. Now they are 32 day's Blooming and the hair's seem to be browning more than normal for this age. I have grown this plant under HPS and LED before so I will know if the end product is what I am hoping for. There are more intense bulb's than what I am using.

i am on my third grow so i am still a noob but the first 2 grows i used one 4 foot 10000 kelvin t5 with uva radiation that i got from htg supply in my 4 bulb t5 fixture. the other 3 are 3000 kelvin bloom bulbs. i like the idea that the bulb is not strictly uva so i am getting some visible lumens(bluish though) out of the lamp. my buds are always very densely covered with trichomes. i have grown 5 different strains with similar results. i run the uva bulb on the same 12/12 timer i have the rest of my lights on. the general consensus of those who have smoked the buds is that the smoke is much better than any of the 'good' weed sold in my area. the flavor of my grows has been ok. not strong enough in my opinion but i have been a nervous nelly and harvested both times too early and as i understand it, that can affect the terpenoids(flavor and smell).

medicinehuman said:

Well, I put 2-26 watt UVB lizard lamps onto a couple plant's in a closet. They were around 3 week's into bloom when I lit them up. Now they are 32 day's Blooming and the hair's seem to be browning more than normal for this age. I have grown this plant under HPS and LED before so I will know if the end product is what I am hoping for. There are more intense bulb's than what I am using.View attachment 3029513View attachment 3029514

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Too much UV can be bad. I run a single 24 watt T5 HO Reptisun 10.0 UVB bulb for 5 to 6 hours in a 3' x 3' tent.

medicinehuman said:

Well, I put 2-26 watt UVB lizard lamps onto a couple plant's in a closet. They were around 3 week's into bloom when I lit them up. Now they are 32 day's Blooming and the hair's seem to be browning more than normal for this age. I have grown this plant under HPS and LED before so I will know if the end product is what I am hoping for. There are more intense bulb's than what I am using.View attachment 3029513View attachment 3029514

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Are you using ONLY uvb bulbs?

I have her under a Pro grow 260. It would be doing quite well if all it just UVB.

ProdigalSun said:

Are you using ONLY uvb bulbs?

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I'll cut it back to about 4 hours, that's what some study suggested.

captainmorgan said:

Too much UV can be bad. I run a single 24 watt T5 HO Reptisun 10.0 UVB bulb for 5 to 6 hours in a 3' x 3' tent.

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last time I had pistils die back it was too hot in the room. I'd try taking the reflectors off and just running one bulb. That room looks quite small for 50w of uv. Your definitely cooking them a bit

kinda looking at UVB like nutrients now. Hit them hard less often or nice and easy the whole way..

Might want to check the spectrum on that bulb and see how it compares to a reptisun or Arcadia UVB bulb. Might not be the best spectrum.

My one cent ,here ...

Uvb should be utilised from start of growth cycle (veg ) in low power ( lamp pretty far from plants ),so the
plants will have the time to 'get used ' to added UVB...
As cycle moves on ,Power of UVB radiation should be increased gradually ,to peak around 4-5-6 week of flowering .
Then it should gradually decreased .Last two-three weeks of flowering (before harvesting ),UVB (or UVA ) ,should be not utilised.
It has be switced off ,in the last 15-20 days ...
Otherwise ...
It will degrade Delta9-tetrahydro-Cannabinolic acid into cannabinolic Acid ,which after decarboxylation ( "curing " ) will be Cannabinol....

https://en.wikipedia.org/wiki/Cannabinol

http://sensiseeds.com/en/blog/cannabinoid-science-101-cannabinol/

I'll try that out sds. Herb seemed pretty damn good though last run where I ran it till harvest. Sun dosent take a break where I live...seems "unnatural" ?