I need a botanist. Question about Pr, Pfr, and the need for red light

I have been reading about photoperiodism and phytochrome ratios and have a question about the plants need for red and far red light.

It has been generally "accepted" that the plant wants blue light during veg and red light during flowering. Under this pretense, growers flood their bloom rooms with red light from HPS or "flowering" LEDs. Please tell me if I have missed something, but hear me out:

HPS is more efficient at producing photons because red photons are lower energy than blue photons. It takes more energy to make blue photons than red ones. Since MH spectrums are blue dominant, they produces fewer photons watt for watt compared to HPS. So, a 1000w HPS produces more PAR micro mols than a 1000w MH, and thus would probably produces more bud. But that does not mean the plant likes red light more than blue light. Some carotenoids (from what I have read) prefer (i.e. are more sensitive to) red light, but only slightly more than blue light.

The issue with budding and red light is in the Pfrr ratio. During the day, it is suppose to maintain ~60:40, and if the night is long enough, Pfr drops low enough (I don't know that ratio) to produce flowering hormones (don't know the names). But I can not find any scientific literature saying that more red light makes more bud/flowers/fruit.

So my question would be (for someone that really knows, a botanist, preferably a PhD) is the following assertion correct?

At equal ppfd, it should not matter if the light is more red or blue, as long as there is enough red to maintain the 60:40
Prfr ratio.

Also, there is talk about using far red at the end of the day to rapidly reduce Pfr to Pr and reduce the time needed to reach the flowering ratio. The idea is that they can extend the light time and get more growth hours by reducing the needed amount of dark time. My question about that would be: how much time does the plant need after the flowering ratio is reached to produce "enough" hormone. I thought bud fattening happened at night, while these hormones are being released. If that is the case, you wouldn't want to reduce the dark time. Please let me know if I am confused.

Thanks!

Subbed up. Would like to hear the responses to this. May go do some reading on it myself tomorrow. If no one responds, I'll let you know if I find anything of use.

When you find a PHD on this site let me know. I might roll over in my grave or something.

might not find a php but (god is here) lol

Pm chazbolin

SDS has posted a detailed explanation to this before

GOD HERE said:

When you find a PHD on this site let me know. I might roll over in my grave or something.

Click to expand...

lol I realize not everyone here is a scientist. I have an engineering degree and lots of my classmates were stoners. Surely there are some advanced degree growers on the site. I figured the forum would be a decent place to ask if anyone knew or knew where to find literature on the subject.

Thanks God, but you're not real, lol

Thanks for the responses!

I'm currently working towards a double major in biology and botany, but I'm only going to be a 3rd year starting in May... Not too many focused study classes under my belt yet. Can't wait until I can answer such questions with ease!

And I'm not finding anything in my books. I'm going to B&N to read some books for free later anyway, and am sure I can come up with some things there

There are a few things to mention on this. First, the use of blue light in veg state is not because the plant prefers it or that blue light more efficient. The reverse is actually true. Blue light is used because it promotes shorter stalker plants and reduced internode length. We (for the most part) are growing indoors where height is a limiting factor. Therefore, we want shorter plants. Chlorophyll A and B actually use red light slightly more efficient than they do blue lighting. During the flowering stage, we change over to a more red spectrum because the height has already been controlled and the hormones required for flowering have photo receptors that only use red light. There are other factors as well, like: red wavelengths promote shade avoidance and causes the plant to stretch in an attempt to out grow surrounding plants to compete for light. Then there is the Emerson Effect which most people leave out completely in their studies. Using a red and deep red lighting together gives a quantitative growth and not just a cumulative amount. Meaning, that using (for example) 660 red together with 730 red will give you a growth increase of 4 times the amount you would receive when using only one of those wavelengths and twice the amount when using each of them separately.

In the post https://www.rollitup.org/led-other-lighting/633304-if-you-new-led-want-15.html#post8892470 I listed a few of my favorite research sites/articles. As Snot said, a few of us linked a ton of information in SDS post as well.

^^^ you have it backwards . Blue during veg promotes stretching. Red is added to promote tighter node spacing. In flowering red does promote flower growth but also stretching. Blue is added during flower will promote tighter nodes. Blue region does have the most photons by that is more efficient with the aide of green wavelengths to help absorb more photons. 75% of light absorbed is in the deep red. 650nm-700nm. Now 730nm is used in conjunction with 630nm for flowering. IR regions drive flowering and 760nm for density. Using 730nm for 5 min after lights turn off is mimicking sunset like the long days in the fall to manipulate the plant to go into its phytochrome state faster. By this theoretically. You could run your lights for 14/10 mimicking nature. Its still gets 10 hours I. Phytochrome state ( budding ). With out the IR at the end.it would take 2 hours to go into that state. Hence the 10 hours of phytochrome. 660nm will promote larger flowers.

If you have too much blue during flower It will take longer to initiate and finish flowering and yield will suffer.

Veg 60%-70% blue / 30%-40% red

Flower 30%-40% blue / 60%-70% red.

Induction87 said:

I have been reading about photoperiodism and phytochrome ratios and have a question about the plants need for red and far red light.

HPS is more efficient at producing photons because red photons are lower energy than blue photons. It takes more energy to make blue photons than red ones. Since MH spectrums are blue dominant, they produces fewer photons watt for watt compared to HPS. So, a 1000w HPS produces more PAR micro mols than a 1000w MH, and thus would probably produces more bud. But that does not mean the plant likes red light more than blue light. Some carotenoids (from what I have read) prefer (i.e. are more sensitive to) red light, but only slightly more than blue light.

Click to expand...

Just to add some colour to this claim...

This is an HPS seen through a spectral diffraction grating at different levels of exposure:


And here are some comparisons of different lights with their relative visible spectra


I wonder what a light made from Hydrogen and Helium would look like? Hmmm

The issue with budding and red light is in the Pfrr ratio. During the day, it is suppose to maintain ~60:40, and if the night is long enough, Pfr drops low enough (I don't know that ratio) to produce flowering hormones (don't know the names). But I can not find any scientific literature saying that more red light makes more bud/flowers/fruit.

Click to expand...

Really? I just punched in "Red Light effects on fruit production" into the university search engine and found this amongst many recent papers:

Response of Tomato and Pepper Transplants to Light Spectra Provided by Light Emitting Diodes


Abstract

Growing conditions during transplant production influence seedling quality and performance, transplant establishment, and subsequent yield. The effects of spectra combinations of blue, red, and white light, generated by monochromic light-emitting diodes (LEDs), on physiological and morphological characteristics of tomato (Solanum lycopersicum L.), cv. Kingston, and pepper (Capsicum annuum L.), cv. California Wonder, seedlings were investigated. Tomato and pepper transplants treated with monochromic red, or combinations of red with blue light, produced greater stem diameter, whereas blue light alone, or in combination with red, reduced transplant height. In tomato the most lateral branches were produced on seedlings under blue light, but pepper transplants were not affected. The most leaf area in tomato and pepper transplants was obtained under monochromatic blue or red light, respectively. Proline, an important compound related to plant stress tolerance, was produced at the highest level under blue light in both plants. For tomato, red light alone or in combination with blue or white light reduced the number of leaves required before the first cluster. This occurred in pepper transplants when higher ratios of red light (up to 100%) were applied. For both plants rates of first cluster formation and first yield were higher when combinations of blue and red lights (regardless of their ratio) were used. The most vitamin C was in fruit produced on plants developed from transplants grown under blue light. Fruit total soluble solids were also higher in tomato plants developed from blue light–treated tomato seedlings. There appear to be beneficial effects due to exposure of plants during seedling development to light spectra that extends beyond transplanting. The effects of light spectra appear to be genus or species specific. The LED technology did not differ from other technologies and has merit for production of some vegetable seedlings.


Now, one nagging question I have is WHAT WAVELENGTHS WERE THEY USING?
You think they would have measured that
Damn scientists!
But I don't know if that answers any of your questions...

Probably not...

So my question would be (for someone that really knows, a botanist, preferably a PhD) is the following assertion correct?

At equal ppfd, it should not matter if the light is more red or blue, as long as there is enough red to maintain the 60:40
Prfr ratio.

Click to expand...

Do you really need a PhD to answer that for you?
But as someone else noted, you're more likely to find God on here than a PhD...

Doesn't Govindjee cover this topic in his book on Photosynthesis?


That's just something I dug up while looking at chapter 9... it doesn't answer the question of 60:40 ratios...

Also, there is talk about using far red at the end of the day to rapidly reduce Pfr to Pr and reduce the time needed to reach the flowering ratio. The idea is that they can extend the light time and get more growth hours by reducing the needed amount of dark time. My question about that would be: how much time does the plant need after the flowering ratio is reached to produce "enough" hormone. I thought bud fattening happened at night, while these hormones are being released. If that is the case, you wouldn't want to reduce the dark time. Please let me know if I am confused.

Thanks!

Click to expand...

I don't know if you're confused,
but I sure am

hyroot said:

^^^ you have it backwards . Blue during veg promotes stretching. Red is added to promote tighter node spacing. In flowering red does promote flower growth but also stretching. Blue is added during flower will promote tighter nodes. Blue region does have the most photons by that is more efficient with the aide of green wavelengths to help absorb more photons. 75% of light absorbed is in the deep red. 650nm-700nm. Now 730nm is used in conjunction with 630nm for flowering. IR regions drive flowering and 760nm for density. Using 730nm for 5 min after lights turn off is mimicking sunset like the long days in the fall to manipulate the plant to go into its phytochrome state faster. By this theoretically. You could run your lights for 14/10 mimicking nature. Its still gets 10 hours I. Phytochrome state ( budding ). With out the IR at the end.it would take 2 hours to go into that state. Hence the 10 hours of phytochrome. 660nm will promote larger flowers.

If you have too much blue during flower It will take longer to initiate and finish flowering and yield will suffer.

Veg 60%-70% blue / 30%-40% red

Flower 30%-40% blue / 60%-70% red.

Click to expand...

What up Hy? When did blue start stretching plants ? I think you got it backwards there sir. Blues higher energy is why the HID and CFL crowd like to veg with it, MH and 6500K respectfully. I'm looking at all of my moms that I have under 2x10 watt 5000K (B+Y) array + 1x20 watt 12,000K (B+B) array and there's no stretch in them, or my clones that are under them too and the only red is from scattering, luminescence, etc., so I don't think that's enough to tighten the nodes. This is basically what I was taught about blue light;

Photosynthesis
"Plants photosynthesize nutrients for growth using a green substance in their cells called chlorophyll. Most types of chlorophyll can use the blue spectrum of light more efficiently than the red and far red spectrums of light. More of the blue end causes the cells to be elongated, changing the growth pattern of the overall plant to a more compact size with the nodes closer together. This maximizes the space used and light available for each leaf in the growing area."

Also my Vipar has a fair amount of blue and I don't see any of the other effects you're talking about, nor did I see them with my first 5x60, which was blue heavy, when it was in my flowering room. I don't think my Black Widow will finish in 7 weeks if I remove the blues in my Vipar and replace it with more Red/FR/IR. It finishes around somewhere between 8 or 9 weeks and I think that's about as fast a Black Widow can finish, though I am running 10/14 which is supposed to help finish plants faster. And added 300 watts LOL and run a 660/730nm heavy panel so my findings about time may be biased LOL.

Now if I'm wrong feel free to correct me, cause I don't know it all and I'd rather be correct than right any day of the week.

Fran run only blue and see what happens then add red and green. Ive posted studies in the past that concurs with me.

http://stealthgrow.com/products.htm#SGVEG


In Veg, right? Because there ain't no more green going in my tent. My greenhouse maybe, but not my flowering tent.

Blue only. 460 - 480 wave lengths. With 420 possibly would shorten nodes but actually you know my opinion on 420 stunting and slowing growth. I should of been more specific. Warm whites have 460 peaks and Nw and cw usually have 420 peaks

I.was checking out those sunshine grow pro for a new Veg in a 4x4 tent. But their to heavy in red Imo for veg. But cheap.

I just thought these two tables might be of use in deliberating the matter. I clipped them from that study I referenced earlier
It gives some insight into whether 60:40 even matters...

Actually, where did this 60:40 idea come from, anyway?

Did you even read the link you posted? It clearly states 3 times that the addition of blue light decreased internode length and thickened stems. Nearly everything you stated in post #10 is either wrong or has no scientific basis. Other than a few small photo-receptors (that have not been proven to be in marijuana) green light does nothing to increase photo receptor processes and causes shade avoidance in most plants. (FYI a quick google of shade avoidance syndrome will give you 200 plus articles stating that red and green light cause stretching.) 730nm is not IR.. it is far red.

Yes I did but you obviously didn't read the whole thing. It takes hours to read the whole thing. I have had people argue with me ov er this before. It completely supports everything.

Here's a study on green light.


http://m.pcp.oxfordjournals.org/content/50/4/684.full

Genius far red is IR - infrared .... 700nm - 780nm. Par is between. 400nm - 700 nm. I also stated 760nm. Texas A&M has quite a bit of studies on IR driving flowering.

Also.why do you think all led companies use whites over blues now. For that missing wave length in green and amber and IR region.

Google ed rosenthal speech on led and missing wave lengths. He worked along with Nasa to help design the Apaches.

Green Light: The Forgotten Region of the Spectrum.

...
"Plants do not reflect all of the green light that falls on
them but they reflect enough for us to detect it.

Read on to find out what the role of green light is in photosynthesis"



http://www.heliospectra.com/sites/www.heliospectra.com/files/field_page_attachments/what_light_do_plants_need_2012-10-05.pdf