Another debate question for the experts

[Hushpuppy]

I went back and looked at some of the information that I had seen. Unfortunately I can't find the info online that I had read earlier. The information that initiated my interest in the "blue light" comes from Ed Rosenthal's book, "Marijuana Grower's Handbook", which is an "official course book for Oaksterdam University" in California.

I read on the lighting that, according to Ed, UVA and UVB are beneficial light spectrums that plants recieve from the sun in limited amounts, while UVC has no apparent use for the MJ plant. UVB light from 290-320nm appears to encourage the production of THC, flavonoids, and terpenes, while UVA seems to contribute to photosynthesis and other responses within the MJ plant.

The interesting part that (may be useful for us as growers) is the flowering hormone that is directly responsive to light spectrum and the dark period.

Ed says that the hormone Phytochrome (pr/Pfr) has 2 states within the plant. The inactive state(Pfr) occurs during extended light periods when the plant is absorbing the different spectrums of light. When the plant is placed into full darkness for the proper period of time(12+hours) then the hormone changes to its active form (Pr), which after a few days of high active levels will encourage the plant to switch to the flowering phase.

All that being said, Ed stated that there are two spectrums that affect the hormone Pr/Pfr, the red spectrum around 660-666nm and the blue spectrum around 400-450nm. Any interruption of the dark period with the red 666nm light will cause the Pr hormone to revert back to its inactive form Pfr.

Blue light around the 450nm also has the same effect but to a much lesser degree. At the same time this blue light will encourage plant growth through the transfer of light energy to the chlorophyll.

Ed gives this information for the purpose of being a viable method of sexing plants without disturbing the growth cycle and forcing the plant into full flowering. The method is to have the "blue" spectrum of light on for the 12hour dark period of a 12/12 photoperiod. Having this "blue" light on during the dark period supplies enough energy to support growth while not discouraging enough production of the hormone Pr to produce a limited flowering response.

My hypothesis is; if I were to use a significant amount of "blue 420-450nm" light for only 4-6 of the 12 hours of dark period, I could offset the "stretch" that occures as a result of the plant getting less light after the switch to the 12/12 photoperiod, without affecting the flowering response.

At this point I don't have any data to support my hypothesis other than the information supplied by Ed Rosenthal and a little that I read online. That is why I posed the question here to see if anyone else has heard or considered this. At this point I would not recommend that anyone go out and buy "Actinic" or "black" lights. I intend to do some experimenting with this in the near future and will update everyone when I find out more.

 

[bho_expertz]

I'm gonna buy ... Or will not ?

No i will wait

:48:

 

[BBFan]

I read on the lighting that, according to Ed, UVA and UVB are beneficial light spectrums that plants recieve from the sun in limited amounts, while UVC has no apparent use for the MJ plant. UVB light from 290-320nm appears to encourage the production of THC, flavonoids, and terpenes, while UVA seems to contribute to photosynthesis and other responses within the MJ plant.

Hushpuppy- This hasn't been proven to be true. I've been experimenting with UVB lighting for a few grows now over the last couple years and still haven't gotten definitive results. And certainly no-one in the scientific community supports or has verified this statement to be true. Also, UVB rays are harmful to plants, not beneficial. If UVC could get through our atmosphere- there would be no life on the planet!

And phytochromes (there are many types) are not the defining receptor to induce flowering. Florigens are an elusive hormone that the scientific community has yet to isolate but is what is generally accepted to be the inducer of floral onset in photoperiod plants. The Circaidian Rhythm is what it is. The start of the flowering process goes hand in hand with other processes, most notably senescence. (PfR is the active state of phytochromes, not the other way around).

There are many tried and true ways to reduce stretch that have been used in the horticultural field for years. If there's a way to continue vegetative growth during the onset of flowering, I'd be real interested in reading more about it. But somehow I'm thinking it's not possible.

Interested to see how it works for you.

 

[NorCalHal]

Ed smokes too much............

 

[BBFan]

Yeah Hal. I wasn't gonna say that. Taking some liberties.

 

[Sol]

Right ,that's what i was wondering. Same deal i'm sure i read something about uv lights as well, a long time ago. Then when you reminded me of it , i thought " i have a UV light' like a blacklight. Its a florescent* bulb as well, not an incandescent one. Might be interesting if it had some effect.

 

[mr_chow]

Right ,that's what i was wondering. Same deal i'm sure i read something about uv lights as well, a long time ago. Then when you reminded me of it , i thought " i have a UV light' like a blacklight. Its a florescent* bulb as well, not an incandescent one. Might be interesting if it had some effect.

be careful ... blacklight isn't the same wavelength as actinic

 

[Roddy]

hmmm....interesting!

 

[depetreono]

Once I started reading this thread I couldn't stop. I'm hooked. Let me know how the tests go. Idk if this IS possible but I'm crossing my fingers hopeing you prove it is. This would mean huge increase in yields made in the same amount of time as what we do know. On a profit stand point this could mean seriouse increase in dough. Also more for my own personal use. I'm following this to the end... Keep the knowledge coming guys. And I think led lights are made to produce the exact light or mixture of light you want. But kinda pricey.

 

[soil]

My hypothesis is; if I were to use a significant amount of "blue 420-450nm" light for only 4-6 of the 12 hours of dark period, I could offset the "stretch" that occures as a result of the plant getting less light after the switch to the 12/12 photoperiod, without affecting the flowering response.

hey hush,
IF ed has correct data then i would think your theory should "work". (your thinkin like me......between the lines. )

I have very limited knowledge on uv in general , but BB seems to know his "reefer science" so thats the man i would stick with for testing/advice...... if you ever get that far.


extra , probably un-needed info:
I use an extra blue MH an a regular HPS together for bloom and always have. i have seen little to no difference using 100% MH for bloom or 100% HPS for bloom.







soil

 

[depetreono]

So just for understanding.. you can actually keep light on during the dark period of flowering up to a certain point without disrupting the dark cycle and reverting the plant back to veg if you use ONLY a true blue light between 420-450. Which also for my understanding means only blue light no other colors from the light spectrum. Is this correct?? And does anyone know if this can be accomplished with the new led lighting systems?

 

[Sin inc]

well i have always used a 175 watt mh with hps in my flowering room. i am growing cfl right now but .when i do get some money its will 250 mh with a 400 watt hps, i really have not had a prob with streching i feel like its because of the mh stop the strechwhen i use it with my hps

 

[Hushpuppy]

I am sorry that I never came back and finished this thread. I lost it and then forgot about it.

Ultimately the blue lights failed to do what I had hypothesised. They actually cause more stretching because they kept the plants from going into bloom while not giving enough light energy to prevent stretching.

 

[Sin inc]

thanks for the update hush