UV light or photoinhibition

In my study of botany (especially marijuhana) i have come across some interesting stuff but one thing has stuck out recently and that is the minor debate that UV light has the same effects as too much normal light/Photoinhibition.

It is theorized by some that the plants response to UV light is exactly the same as when too much normal light is provided and hence the same results can be achieved.

I have noted that no member has proved the benefits of UV light and certainly there are no conclusive studies that i have read that link extra THC production to the quantity of UV light provided except that it can cause damage to the plant cells and this is the same system that is seen when providing too much (NON) UV light.

Certainly the idea that you can promote more THC with just ordinary light has caused quite the discussion in non Marijuwana circles and it certainly does seem that what some try to achieve with all those UV bulbs could easily be demonstrated by increasing lumens to a detrimental level.

The plant should react to the damage, whether that be UV or just too much lumens, and produce the same stress response.

Certainly interesting to read and something i have seen before i.e. very sticky buds from over exaggerated lumens without having to add UV bulbs.

2Hearts said:

In my study of botany (especially marijuhana) i have come across some interesting stuff but one thing has stuck out recently and that is the minor debate that UV light has the same effects as too much normal light/Photoinhibition.

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Have you personally experimented with the UV spectrum (UVa/UVb/UVc) in-regards to cannabis?
(and if yes), what anecdotal data were you able to ascertain?

https://www.reddit.com/r/Head2HeadMG/comments/2p1j5r/an_introductory_primer_on_the_utility_of_uv_light/
(good read)

http://silassativarius.org/2014/10/03/does-exposing-your-plants-to-uvb-increase-thc-production/
(info on UVR8 gene, skip the LED plug in the end)

cannawizard said:

Have you personally experimented with the UV spectrum (UVa/UVb/UVc) in-regards to cannabis?
(and if yes), what anecdotal data were you able to ascertain?

https://www.reddit.com/r/Head2HeadMG/comments/2p1j5r/an_introductory_primer_on_the_utility_of_uv_light/
(good read)

http://silassativarius.org/2014/10/03/does-exposing-your-plants-to-uvb-increase-thc-production/
(info on UVR8 gene, skip the LED plug in the end)

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I never bothered experimenting with UV because i could never find a thread where any difference has been noted between that and a control grow so seemed pointless. If there was any kind of credible evidence that increased thc or production im sure companies and members would have jumped ot it like flies to shit as you see with some other products that have sprung up in the last 10 years.

There is two ideas about UV and Photoinhibition, one is they do the same thing and the other is that they are seperate systems......

I wrote this thread because the results people try to produce with UV seem easy to produce with Photoinhibition and where as UV seems to be failing to produce correlated results photoinhibition seems to be producing what UV should with a lot more ease (and obviously electricity costs).

Just saying that UV and Photoinhibition seem to produce the same end results and the stickiest thc buds ive had were from over lighting my flower room.

i use uvb cfls. alot cheaper to run 2 of these vs overlighting with a HID in my opinion.

Kingrow1 said:

I never bothered experimenting with UV because i could never find a thread where any difference has been noted between that and a control grow so seemed pointless. If there was any kind of credible evidence that increased thc or production im sure companies and members would have jumped ot it like flies to shit as you see with some other products that have sprung up in the last 10 years.

There is two ideas about UV and Photoinhibition, one is they do the same thing and the other is that they are seperate systems......

I wrote this thread because the results people try to produce with UV seem easy to produce with Photoinhibition and where as UV seems to be failing to produce correlated results photoinhibition seems to be producing what UV should with a lot more ease (and obviously electricity costs).

Just saying that UV and Photoinhibition seem to produce the same end results and the stickiest thc buds ive had were from over lighting my flower room.

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Thanks for the input, got stuck reading a couple of links concerning "photoinhibition"

Did you run into any problems increasing "light intensity" on your cannabis plants?
(ex: http://www.growweedeasy.com/too-much-light)

~ all i can add to the whole UV thing is genetics.. not all strains/phenos respond the same

Been thinking about adding UV to my next grow, anyone read these?

http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.1987.tb04757.x/full

http://www.hightimes.com/read/grow-hack-how-use-uv-lamp-increase-thc

https://silassativariusdotorg2.files.wordpress.com/2016/01/uvb-effects-on-photosynthesis-growth-and-cannabinoid-produciton-in-cannabis-sativa.pdf

Ive read a lot about UV but ive never seen anything conclusive to make me want to try. Uv light isnt very plant friendly which is where the link to photoinhibition/too much light comes from as both should force the plant to protect itself.

I cant remember which member did it but not so long ago someone here tried to do a comprehensive grow with UV included. Many have tried but none seem to confirm it made better plants.

Naturally the sun kicks out a fair amount of UV on a sunny day so there must be a lot of truth to it but as for better plants, ive not seen anything that has convinced me yet.

I would add UV to my grow if i could yeild more.

Kingrow1 said:

I would add UV to my grow if i could yeild more.

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it won't increase yield at all.
i have seen some info where alot of strains from high uvb areas (high altitude, equator, etc) have higher thc.

supposed to increase trichomes which in effect act as sunscreen for the plant to block uvb.

grow lights provide hardly any uvb. especially hps. and especially if the bulb is blocked by glass of a cooled hood.

for $30 for 2 23w cfls and 2 light sockets, it's well worth it. why not try to recreate the sun as much as possible?

rkymtnman said:

it won't increase yield at all.
i have seen some info where alot of strains from high uvb areas (high altitude, equator, etc) have higher thc.

supposed to increase trichomes which in effect act as sunscreen for the plant to block uvb.

grow lights provide hardly any uvb. especially hps. and especially if the bulb is blocked by glass of a cooled hood.

for $30 for 2 23w cfls and 2 light sockets, it's well worth it. why not try to recreate the sun as much as possible?

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By yeild i mean more thc (sorry) but obviously no reduction in bud size. Those trichs should also be increased by too strong of a light (so the link goes).

Over in my area we have a vast selection of various different UV bulbs that are in T8 and T5 flourescent size so if i did id use them rather than the cfls.

Coincidentally flourescents use a shed load of UV rays but they are absorbed by the phosphorus coating inside the bulb, a UV flourescent just allows the UV through the bulb without being absorbed (by my thinking) although id need to check that out.

They push cfls hard and ive used every single size but always found that although they are a little weak when compared to the equivelant wattage in other bulbs i.e. a 24 watt cfl is a small not that powerfull light on its own but a 24watt T5 is much brighter. The 250watt cfl i had was not as bright as a 250watt hps.

Cfls and leds just cant quite compare but with the ever advancing technology im sure they will sooon become a lot better.

Kingrow1 said:

Over in my area we have a vast selection of various different UV bulbs that are in T8 and T5 flourescent size so if i did id use them rather than the cfls.

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agreed. the best option inmy opinion would be to try to add some uv bulbs from a tanning bed.

i think the effective range of my cfls are 20 inches.

most reptile websites have all types of uvb bulbs in stock. i have one more grow on these cfls and i'm gonna switch to a t5 or t8 setup. would be easier and have better coverage in my flower room.

my main question about using too much HID vs UVB bulbs is how do you know what light level with a HID is too much?

let's say i have a 600 hps in my 3x4 room. is adding an extra 250 hps gonna do it? would i need a 400? would i need another 600? seems like it would be hard to figure out the threshold for the HID

rkymtnman said:

my main question about using too much HID vs UVB bulbs is how do you know what light level with a HID is too much?

let's say i have a 600 hps in my 3x4 room. is adding an extra 250 hps gonna do it? would i need a 400? would i need another 600? seems like it would be hard to figure out the threshold for the HID

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Assuming were still talking photoinhibition you can find the threshold by finding the point a plant stops stretching for the light. At this point we can assume the plant is no longer looking for extra light. Hard to judge for flowering but as a plant grows you can get a general idea of when its happy and when it wants more. The rest is just experience and tweaking things grow after grow i guess. Obviously as a plant grows it will require more and more to a point.

I'm sticking with UV-A myself for now. It's known that plants do use UV-A, it increases phenolics, which are building blocks for THC. CFL blacklights are cheap and almost all of the spectrum is UVA. So far with 52w/sq m I've noticed leaves curl downward toward the tips and some browning of leaf margins. I tried some and it did seem more potent than last time without UV. They're growing well enough. It's just the final 2 weeks I'm using it, 12 hrs a day.

You want to go to uvb nanometers.

http://www.internationalhempassociation.org/jiha/iha01201.html

I can go on for days about ultraviolets and many see a change in the next run after adding uvb
It doesn't only increase protection it also changes the chemical make up and stacks the cuticle of the trich thicker.

@ArcticOrange whats your take on the subject?

rkymtnman said:

my main question about using too much HID vs UVB bulbs is how do you know what light level with a HID is too much?

let's say i have a 600 hps in my 3x4 room. is adding an extra 250 hps gonna do it? would i need a 400? would i need another 600? seems like it would be hard to figure out the threshold for the HID

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Its not so much about pumping more watts... its more about hitting your plant with the right nanometers. Photon color is much more important.

rkymtnman said:

it won't increase yield at all.
i have seen some info where alot of strains from high uvb areas (high altitude, equator, etc) have higher thc.

supposed to increase trichomes which in effect act as sunscreen for the plant to block uvb.

grow lights provide hardly any uvb. especially hps. and especially if the bulb is blocked by glass of a cooled hood.

for $30 for 2 23w cfls and 2 light sockets, it's well worth it. why not try to recreate the sun as much as possible?

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The increase in yield comes from the extra trich coverage.

Can confirm, was running uva without uvb and have since added the uvb, definitely made a difference, ill take some pictures tomorrow, ive always got some going in my thread as well

2Hearts said:

The plant should react to the damage, whether that be UV or just too much lumens, and produce the same stress response.

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No...its not really a stress response, as mentioned uvr8 is activated which increases precursors to olivetolic acid

Raising light intensity, can bleach from too little chlorophyll production. Leaves will widen and thicken, buds are tight etc..
These are hormonal responses but trich heads are not directly affected.. so long as yiu don't fry them. This is very different from the response seen from uvb and activated receptors


Theres no point where the plant just stops stretching. I can grow 3-5 fingered plants all the way to harvest that are just as frosty potent and tasty as the same strain blasted with light pushing 11-13. fingers.
Thats not how it works lol



Yea i already told you my thoughts in your uva thread... good luck man, doesnt seem like a good idea

ArcticOrange said:

Can confirm, was running uva without uvb and have since added the uvb, definitely made a difference, ill take some pictures tomorrow, ive always got some going in my thread as well

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But did the UV-A alone increase potency at all? Maybe both together would be good. I actually had a couple blacklight CFLs, which put out all UV-A, and I put them in splitter sockets with the Reptile lights. The CFLs put out a huge spike in the UV-A range, way more than the reptile lights. But I still have some UV-B from the rep lights plus some extra PAR light, since it's just a tropical rep light rather than desert (I bought the wrong one, oh well).