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please help light saturation level

yes we did discuss it, I still feel like I didn't find the answers I was looking for so I'm still looking
 
Yes in theory you are correct. But I was thinking about a particular situation which I did not articulate well. Let's say you were using HPS which is too high in Infrared to increase intensity past a certain point. But if the spectrum was closer to natural, you could increase overall intensity and possibly photosynthesis. Another case is when a plant leaf thickness increases due to exposure to green and yellow and actually fixes more carbon because photosynthesis is occurring deeper into the leaf.
I don't think I am explaining the situation well. It would be better to discuss over a beer or two.
 
Could be both actually. Up to a point, more light, more energy and growth. Filling holes in the spectrum may also increase Photosynthetic efficiency. I think Dan will disagree with this...and he could easily be right.
There are some huge effects of growth response that are not Photosynthetic. Messages that the plants read from the light they are exposed to. The biggest and best understood of these is the R:FR ratio. (Red:Far red). Generally, there's more red light than far red light. Far red penetrates deeper into a canopy, so in the shade the plants get the message to extend, also known as shade response. Because long night mimics FR light in it's chemical responses, we get the stretch when we change over to 12/12. FR can be used as a supplement to bring on flowering as well, but only if Red isn't being supplemented at the same time.
So growth is dependent first on available energy, but it is controlled by other complex interactions.
 
If there is anything further i can do let me know. There are no plant biology references or online articles relating to maximum daily light integral, nothing of any kind. Even knowing how the plant works from a physiological standpoint does not suggest anything either. The only thing that could remotely relate would be something to do with a plants circardian rythem.
 
Thats pretty accurate, id agree. The Pr to Pfr ratio is only used for flowering but the photorecepters for the specific wavelengths respond by photomorphogenesis.
The increased growth will mainly be from the added light, more photons, more photosynthesis. Even if the light intensity is the same at the canopy, there are more photonic particles hitting the plants increasing "total" photosynthesis.
Increasing spectrum does not improve photosynthetic efficiency. Emerson studied this years ago, ultimately the amount of photosynthetic action is dictated by the photon count reaching the plants(although yellow and red are slightly more efficient as seen on the mccree curve).
 
Ah dunno about links but you could try some plant biology books ?

A good place to start.
Plant biology by stern bidlack jansky.
 
Some very shallow, but specific articles for intro on Boundless.com.
Great articles about light in Greenhouse Product News, gpnmag.com
Search for R to Fr ratio
Also an article about green light, blue light, etc
By Erik Runkle, floriculture at Michigan State also at gpnmag.com
 
In response to the awesome amount of information both Soilscience and Danofdanger provided my experience and research has supported points that they both brought up. My experience is related to LED lights only but I've used LEDs that provide various spectrums to meet "full spectrum" lighting. At first I used a 400 watt led for a 3x5 foot space and it worked pretty well but I had to keep rotating the plants to make sure they all received about the same coverage. Next I added another Full spectrum 320 watt LED that had veg and bloom options. This provided better coverage and a slightly broader spectrum that seemed to increase yield by about 20% within the same space. But the coverage wasn't really uniform because the two different lights had different footprints. I sold those lights and got two 4' long LEDs that produced true full spectrum lighting (light that appears white_like sunlight-no pink/purple light), including some green light in the 500-550 spectrum which is often claimed to not provide any benefit. I'm no biologist/physicist but it sure didn't hurt. Together the two lights draw 640 watts, being 4' long and 4"x4" square, when set into the 3x5' space they provide very even coverage and 700 umol/s at 24" over the entire area. This lighting setup resulted in the best quality and quantity so far and I'm going to stick with it. Partly because they worked so well and partly because I have a lot invested in them. During the first 4 weeks I supplemented with a 6500 K light bar set between the two main lights, for the next 4-5 weeks I used only the main LED's, and for the last 3-5 weeks I used the two main lights with one FR light bar with the intension of enhancing flowering. Instead of leaving them in the dark for the last three days as some folks like to do I used the RF light bar only for the 12/12. Light intensity was very low but trichome production seemed to continue to increase. Grow mediums and nutrients were very similar for each of these grows, for whatever thats worth. The true full spectrum white lights drawing 640 watts produced better and more product than the two previous lights which drew 720 watts. I believe the difference was due to the more even light intensity/distribution over the entire grow area provided by the new light setup. Also perhaps the true full spectrum white light may have been providing some wavelengths that provided benefits not easily determined. The new LED's also have the best penetration of any of the previous ones. Another benefit was I didn't have to rotate the plants because they all got exactly the same PPFD and umol/s, and I didn't have to wear any glasses except regular UV sunglasses. My opinion is that the more even the coverage and the more umol/s at specific distances, the more productive your lighting setup will be. You really have to dig into the specs for any lights to find out how much light drops off beyond the few square feet directly beneath them and the intensity of the umol/s at specific distances. Not all are created equal. Beyond this its gets a little too scientific for me_ I'm sure danofdanger and soilscience can add to that. Hope that helps.
 
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