Should I add UVB Light?

[Moe.Red]

25% would be 250mg per gram. 20% would be 200mg per gram

Correct,
i get the same thing.

So density is irrelevant except for smoker appeal, right?

 

[Moe.Red]

Meanwhile...

I am running UVA bars in my LED tent. I have grown over a dozen Durban Poison, and this is the first I have ever seen them go purple.

 

[Aqua Man]

Correct,
i get the same thing.

So density is irrelevant except for smoker appeal, right?

Yeah... pretty much. But there is a lot of hype around color and density so I'd say it has a fair bit of impact on perception.

 

[Aqua Man]

Meanwhile...

I am running UVA bars in my LED tent. I have grown over a dozen Durban Poison, and this is the first I have ever seen them go purple.

Sexy.

 

[Moe.Red]

Yeah... pretty much. But there is a lot of hype around color and density so I'd say it has a fair bit of impact on perception.

Now the question on the Purple Kush getting purple under the Flower Powers, perhaps it's UVA that does that since I'm getting it on this Durban too.

Too many variables for sure, but If I could get the colors without impacting yield out of just UVA, that would be interesting to know. I don't think the UVA harmed the plants in any way.

 

[Aqua Man]

Now the question on the Purple Kush getting purple under the Flower Powers, perhaps it's UVA that does that since I'm getting it on this Durban too.

Too many variables for sure, but If I could get the colors without impacting yield out of just UVA, that would be interesting to know. I don't think the UVA harmed the plants in any way.

View attachment 1117615

Yeah I don't think it will either. Interesting though because anthocyanin is more present where less photosynthesis is occurring and higher stability in lower temps as they usually don't do as well over 70-75f

 

[Moe.Red]

Yeah I don't think it will either. Interesting though because anthocyanin is more present where less photosynthesis is occurring and higher stability in lower temps as they usually don't do as well over 70-75f

It's only really dark on the small buds on the sides.

Here are my temps in that tent:

That's taken above the canopy, leaf temps are in the range you mention.

 

[Moe.Red]

Yeah I don't think it will either. Interesting though because anthocyanin is more present where less photosynthesis is occurring and higher stability in lower temps as they usually don't do as well over 70-75f

Wait, I just thought of something. The Purples that are dark in the UV test tent are also on the same side as the AC unit. They pretty much get the majority of the first air that comes out of the AC. It's possible the lower temp is a requirement and UV has nothing to do with it.

 

[MIMedGrower]

Just to note. Many strains i and others have grown under Phillips 315 cmh turned purple and some strains finished about a week earlier than when grown under hps.

 

[Moe.Red]

Just to note. Many strains i and others have grown under Phillips 315 cmh turned purple and some strains finished about a week earlier than when grown under hps.

I think you are right and this is a UV response.

Phenylpropanoid - Wikipedia

en.m.wikipedia.org

But in reading up on

Anthocyanin​

Anthocyanin - Wikipedia

en.m.wikipedia.org

The darker colors can also aid in temp protection for the plant.

Based on less than all the facts my gut tells me UVA is the primary driver of purple in these plants. The other half the tent is Far Red. Nothing interesting to report there.

 

[Aqua Man]

ok so i should clear up that anthocyanin is seem more often in areas that aren't as photosynthetic like petioles... you always see ppl post about the purpling on them and 99% of the time it's due to high light.

but it doesn't mean it takes away from photosynthesis just usually more prevalent there because photosynthesis produces chlorophyll.

definitely light is increasing photosynthesis and anthocyanin. Just that in higher tenos anthocyanin breaks down so its usually less pronounced.

copy pasted.

Conclusions​

Lc and Mitchell petunia have provided a unique, near-isogenic experimental system to examine the mechanism for vegetative light-induced anthocyanin pigmentation and the effect of pigmentation upon photosynthesis, whilst removing the variability associated with plants of differing genetic backgrounds or developmental stages. The enhanced pigmentation of Lc petunia has allowed us to demonstrate that sub-epidermal anthocyanins do act as a light screen, but without affecting the maximum photosynthetic rate. The fact that intense foliar pigmentation in Lc petunia occurred only when grown under high light points to the existence of a light-induced regulatory factor responsible for the activation of the anthocyanin pathway. Given that both the bHLH (Lc) and WD40 (An11) were constitutively expressed in Lc petunia, and that a MYB anthocyanin-regulator Rosea1 was able to complement the high-light requirement, the endogenous regulatory factor appears likely to be a MYB protein

 

[MIMedGrower]

I think you are right and this is a UV response.

Phenylpropanoid - Wikipedia

en.m.wikipedia.org

But in reading up on

Anthocyanin​

Anthocyanin - Wikipedia

en.m.wikipedia.org

The darker colors can also aid in temp protection for the plant.

Based on less than all the facts my gut tells me UVA is the primary driver of purple in these plants. The other half the tent is Far Red. Nothing interesting to report there.

We thought it was because of the full spectrum with so much blue compared to hps but after the last few years seeing led lamps develop similar sunlight spectrums and finish plants quite green I have to agree with you. UVA may be the purplizer. (New made up weed term) :-)

 

[DennisBrown]

I think you are right and this is a UV response.

Phenylpropanoid - Wikipedia

en.m.wikipedia.org

But in reading up on

Anthocyanin​

Anthocyanin - Wikipedia

en.m.wikipedia.org

The darker colors can also aid in temp protection for the plant.

Based on less than all the facts my gut tells me UVA is the primary driver of purple in these plants. The other half the tent is Far Red. Nothing interesting to report there.

We have 4 foot F32T8 UVA bulbs, centered on 366nm, no UVB just the single phosphor, if you ever got curious. Runs the same fixture as Flower Power. I'm overstocked on them, as they were designed for wood finishing and got superseded by the SG series (the parent of the Flower Power), which is better for that purpose. Can sell them cheap, like 10 dollars if someone buys a few. Good lamp with the built in reflector, called the "Curall 365". I've been trying to find a hemp grower to do some tests (free to them) as my theory is that if you take already dried and cured buds and expose them to lots of this frequency, you convert THC -> CBN, which is unregulated and can take hemp that is over the THC limit and push it down. That's the theory, anyway. 365-366 is the center band where oxidation is accelerated, be it tanning skin or catalytic reactions in many UV finishes.

 

[Moe.Red]

We have 4 foot F32T8 UVA bulbs, centered on 366nm, no UVB just the single phosphor, if you ever got curious. Runs the same fixture as Flower Power. I'm overstocked on them, as they were designed for wood finishing and got superseded by the SG series (the parent of the Flower Power), which is better for that purpose. Can sell them cheap, like 10 dollars if someone buys a few. Good lamp with the built in reflector, called the "Curall 365". I've been trying to find a hemp grower to do some tests (free to them) as my theory is that if you take already dried and cured buds and expose them to lots of this frequency, you convert THC -> CBN, which is unregulated and can take hemp that is over the THC limit and push it down. That's the theory, anyway. 365-366 is the center band where oxidation is accelerated, be it tanning skin or catalytic reactions in many UV finishes.

I’m thinking I might take you up on those cheap uva bulbs for my next run of THC Victory. This is a supposed high THCV strain that were really expensive so no UVB on the first run of these. But I can compare left vs right side of tent.

I currently feel UVA is the spectrum that has the potential to do the most good. This side by side also has the potential of testing minor cannabinoid response carefully. Shooting for South Africa

 

[Moe.Red]

This is in the LED tent on the Durban Poison that was showing purple. Look how the purple goes away on the petiole where a sugar leaf is blocking the UVA from above:

The only purple in this whole tent is on the top where UVA is hitting it directly. I'm only running 4 hours a day, I think if I bumped that up to 8 or 10 it would add a lot more color. If that's important to you. Not sure if it is to me, but it's still cool to learn how to steer your plants a specific way with a little forethought. Durban is not known for being purple.

 

[MIMedGrower]

This is in the LED tent on the Durban Poison that was showing purple. Look how the purple goes away on the petiole where a sugar leaf is blocking the UVA from above:


View attachment 1118493

The only purple in this whole tent is on the top where UVA is hitting it directly. I'm only running 4 hours a day, I think if I bumped that up to 8 or 10 it would add a lot more color. If that's important to you. Not sure if it is to me, but it's still cool to learn how to steer your plants a specific way with a little forethought. Durban is not known for being purple.

You may be overthinking this. Petioles look like that all the time as nutrients are moving out of the leaves to go where needed.

 

[Moe.Red]

You may be overthinking this. Petioles look like that all the time as nutrients are moving out of the leaves to go where needed.

Taken in conjunction with flowers going purple (posted before) and only under UVA, not to mention how many times I have grown this strain out, I don't think I am.

If this were a nute issue, the entire grow is sharing identical nutes, soooo.... why just these? And why take a break in the shade?

 

[DennisBrown]

I’m thinking I might take you up on those cheap uva bulbs for my next run of THC Victory. This is a supposed high THCV strain that were really expensive so no UVB on the first run of these. But I can compare left vs right side of tent.

I currently feel UVA is the spectrum that has the potential to do the most good. This side by side also has the potential of testing minor cannabinoid response carefully. Shooting for South Africa

One of the things a lot of manufacturers don't like to admit is what they don't know. Way back 20 years ago, we made the decision to use only UVA to "water down" our UVB lamps, ie: to make them less than a dangerous 100% UVB lamp. My gut told me that UVA plays a roll, and we are slowly learning that it does, but it is different frequencies that do different things. It's kind of why we did so many prototypes with the Flower Power. I wanted it to hit everything between 280-380nm. Over 380 is fine, we just didn't design for it. Most UV lamps, for any purpose, don't do that, they have deep troughs in the spectrum with only peaks at the main phosphor points. Getting those middle frequencies requires either using multiple phosphors for those points (problematic for a number of reasons, including cost and life) or blending in a ratio that gives you a lot of harmonics in the right places, which is what we did. We didn't start out with the goal of 34%, we just landed there. My first impression back then was to hit 25% UVB which would have worked, but the spectrum missed some of those fat curves, it wasn't as "pretty". So we kept mixing phosphors until we had a lamp that hits all the real UV points, in anticipation that those points would be found to be useful later on. ie: We wanted a *real* full spectrum UV bulb.

 

[Moe.Red]

One of the things a lot of manufacturers don't like to admit is what they don't know. Way back 20 years ago, we made the decision to use only UVA to "water down" our UVB lamps, ie: to make them less than a dangerous 100% UVB lamp. My gut told me that UVA plays a roll, and we are slowly learning that it does, but it is different frequencies that do different things. It's kind of why we did so many prototypes with the Flower Power. I wanted it to hit everything between 280-380nm. Over 380 is fine, we just didn't design for it. Most UV lamps, for any purpose, don't do that, they have deep troughs in the spectrum with only peaks at the main phosphor points. Getting those middle frequencies requires either using multiple phosphors for those points (problematic for a number of reasons, including cost and life) or blending in a ratio that gives you a lot of harmonics in the right places, which is what we did. We didn't start out with the goal of 34%, we just landed there. My first impression back then was to hit 25% UVB which would have worked, but the spectrum missed some of those fat curves, it wasn't as "pretty". So we kept mixing phosphors until we had a lamp that hits all the real UV points, in anticipation that those points would be found to be useful later on. ie: We wanted a *real* full spectrum UV bulb.

Very interesting to learn the engineering side of what goes into this. In my real life I used to be a color theory expert in the printing industry. There are a lot of similarities in the complexity of mixing colors for an image to what you are doing.

You probably already know that purple is a made up color in each individuals mind. It’s when you blue and red rods and cones fire but green does not. Your brain interprets that as purple.

 

[Pondracer]

Havent logged in for a few weeks and this is the first thread I check :)