# Light absorption - Lies from Sunmaster?



## peach (Feb 22, 2009)

I've been doing a ridiculous amount of reading around photosynthesis recently and noticed something. 

A lot of hydroponic sites show the following graph (or something very similar), which is from the Sunmaster website;







Here is the spectrum for chlorophyll (b is similar and the carotenoids aren't that far off, neither do you find much of them in leaves);







Why does their graph show plants as absorbing green, yellow and orange light almost as well as they do red and blue? It looks like they've drawn an almost straight line between the peaks.

The fact 99% of plant leaves are green should be a clue that's not right.

SunMaster are not the only people using this graph. I have seen it a lot of different places but the majority of them were selling lamps. I haven't seen it in any scientific literature. Neither are NASA's LED experiments using green, yellow or orange light sources. 

Here is the spectrum of the Sunmaster Super HPS. Compare it with their own graph of plant sensitivity and that of cholorophyll's absoprtion spectra;


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## Roseman (Feb 22, 2009)

Same way people pass around info about CFS vs HID Lights, or using mollasses, or all the other crap they post that starts with "I heard that............." 

People will repeat anything.


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## weedyoo (Feb 22, 2009)

Roseman said:


> Same way people pass around info about CFS vs HID Lights, or using mollasses, or all the other crap they post that starts with "I heard that............."
> 
> People will repeat anything.


i see this alot on this forum. or people mixing up info


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## Uncle Ben (Feb 23, 2009)

I have a saying about the social dynamics of the internet, "Someone says it, someone repeats, therefore if must be true." 

I did alot of research many years ago on HID lights, experimented alot, and found that you need to take spectral graphs with a grain of salt. Experience is what matters. For example, Osram used to have two 600W HPS, the regular and the Plant-A, the latter supposedly having more blue. The spectral graphs were the same. I had a link where someone said companies were falsely stamping their lamps as something they're not, rumors of premature failing, etc. If you can't trust the manufacturer to get it right, who can you trust?

Having said that, I have grown some really nice plants from start to finish with a plain jane HPS. You don't need this and that, conversion lamps, etc. unless you wish to contribute to the bank account of a hydro vendor. The best info I've seen on lighting is Jorge Cervantes' fairly new bible, the real thick one with alot of photos. He did the measurements of various kinds of hoods and lamps. You're buying light, so a well designed and well built hood is very important.

Good luck,
UB


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## mindphuk (Feb 23, 2009)

peach said:


> I've been doing a ridiculous amount of reading around photosynthesis recently and noticed something.
> 
> A lot of hydroponic sites show the following graph (or something very similar), which is from the Sunmaster website;
> 
> ...


Maybe because the first chart is total photosynthetic response and your second graph is chlorophyll A only.
If you look at the other photosynthetically active pigments. plants have additional pigments that participate in photosynthesis. These are indeed called antenna pigments. 

&#946;-carotene and the two xanthophylls also have conjugated double bonds and rings at either end, this gives the molecules the ability to absorb light. These are yellow-orange pigments and they absorb light in the blue and green areas of the visible spectrum. 







Although you are correct, that first chart looks wrong.
Here's a better one IMO


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## Uncle Ben (Feb 23, 2009)

mindphuk said:


> Maybe because the first chart is total photosynthetic response and your second graph is chlorophyll A only.
> If you look at the other photosynthetically active pigments. plants have additional pigments that participate in photosynthesis. These are indeed called antenna pigments.
> 
> &#946;-carotene and the two xanthophylls also have conjugated double bonds and rings at either end, this gives the molecules the ability to absorb light. These are yellow-orange pigments and they absorb light in the blue and green areas of the visible spectrum.


You make some good points. It's been a while, but I believe chlorophyll A is the most important of the pigments regarding carbo production and one that most folks concentrate on in their discussions.


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## doctorchaos555 (Feb 23, 2009)

Lets make an advanced organic chemistry thread.


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## born2killspam (Feb 23, 2009)

My guess is the manufacturers come up with their gas mixture, make the bulbs, get experimental spectral output, refer to the absorbtion spectra of the various pigments known to photosynthesis, and then model a theoretical plant with pigment proportions that would have a very impressive action spectrum match with their bulb, and print that action spectrum on the box.. Then they'd go back to their experimental spectrum, which would be a series of distinct spikes like the terpine absorbtion graphs Greenhouse Seeds posts on their strain.. And come up with some perverse d_lambda to integrate the energy over wavelength in order to make a pretty continuous spectrum that they can colour like a rainbow, and print that on the box.. (Pretty cynical huh?) 
I'd LOVE to see them print actual spectral output on boxes..
On the topic, heres a neat little toy/tool..
http://www.instructables.com/id/Naff-Movie-into-_DVD-Spectra_/


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## Jobo (Feb 23, 2009)

Its simple really, your trying to compare 2 graphs which arent displaying the same data.

The first is sensitivity to light, which is not necessarily the same as light absorption, which is what is displayed in the second.


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## Uncle Ben (Feb 24, 2009)

The first two graphs in post #1 are based on PAR, the 3rd one is based on visual.

Yes, certain gases are your friends. 

TEXAS, where farting is considered a sport,
Tio Bendejo


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## peach (Feb 25, 2009)

mindphuk said:


> &#946;-carotene and the two xanthophylls also have conjugated double bonds and rings at either end, this gives the molecules the ability to absorb light. These are yellow-orange pigments and they absorb light in the blue and green areas of the visible spectrum.


I know there are accessory pigments, but they're usually swamped by chlorophyll A, which is by far the most dominant pigment in most green plants.

I agree that the second graph looks more realistic; it's basically chloro a & b with carotene.



Jobo said:


> Its simple really, your trying to compare 2 graphs which arent displaying the same data.
> 
> The first is sensitivity to light, which is not necessarily the same as light absorption, which is what is displayed in the second.


I spotted that. What bothers me is the weighting they're putting on things like carotenoids for response. It looks more like they've compiled all the pigment response curves into one graph,

Does anyone have any links to lab work demonstrating that yellow, orange and green are so important for growth?

Surely if they were so vital, it'd be kind of easy to find quite a lot of information on the need for providing it.

According to NLite, yellow light promotes chlorophyll synthesis. I will investigate.

I'm willing to stay open minded on it but it's worth noting that the emission spectrum of HPS (without any tweaking to be better for plants), naturally produces a really huge peak around the yellowy area. So it would be in their interests to suggest it's necessary.

Sodium discharge spectrum;








Protochlorophyllide oxidoreductases might be worth looking at. I'm trying to find their activity spectrum. The enzyme can break down protochlorophyllide into chlorophyllide, which seems to be a precursor of chlorophyll synthesis. It happens only in the light for plants that flower, as cannabis does.

"That which remains of a chlorophyll molecule when the phytyl group is removed.


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## Brick Top (Feb 25, 2009)

One thing to consider is called marketing. Each company will attempt to make their product appear to be the wonder product of the ages, the product that does it all and does it the best so do not be at all amazed if some information given is slightly embellished for reasons of marketing.


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## weedyoo (Feb 25, 2009)

Uncle Ben said:


> I have a saying about the social dynamics of the internet, "Someone says it, someone repeats, therefore if must be true."
> 
> I did alot of research many years ago on HID lights, experimented alot, and found that you need to take spectral graphs with a grain of salt. Experience is what matters. For example, Osram used to have two 600W HPS, the regular and the Plant-A, the latter supposedly having more blue. The spectral graphs were the same. I had a link where someone said companies were falsely stamping their lamps as something they're not, rumors of premature failing, etc. If you can't trust the manufacturer to get it right, who can you trust?
> 
> ...


good points i avoide buying any thing at "hydrostor"

shows people just want to profit


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## peach (Feb 25, 2009)

From what I can find so far, it seems chlorophyll synthesis is actually stimulated by some band of light from the normal blue chlorophyll peak to somewhere in the middle of green, which is thought to be due to carotenoids.

Remember that despite being orange / yellow, carotenoids actually absorb greeny blue light. There's also tens of times less of them in a normal chlorophyll system, if not a hundred or so times. So they're not an adequate explanation for why that gigantic yellow orange peak is a good thing.

I do suspect a very strong marketing element at play. Nlite says yellow light is needed because it improves chloroplast synthesis (well, the two scientific documents I've found claim it's actually blue > mid green light that does this) and to 'increase lumen rating' (great, but what do lumens have to do with par watts? nothing, they're a massive figure to stick in a beginners face and say 'highest lumens out there!'). Again, from a bulb that inherently emits a huge quantity of yellow light. Hmmmmmmmmmmm


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## born2killspam (Feb 25, 2009)

> Remember that despite being orange / yellow, carotenoids actually absorb greeny blue light.


Its obviously in their best interest to make a decent colour spectrum for whatever purpose.. They'll obviously make as good of choices as any as far as anything feasible goes.. But when the science is over, the perversion of science for marketing begins..


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## GreenHog (Feb 25, 2009)

It looks like Sunmaster used the graph for solar output not photosynthetic absorption.


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## Uncle Ben (Feb 26, 2009)

Use a regular HPS from start to finish and don't worry about it. I have, and they were some of my best gardens too. "Color corrected" lamps, conversion lamps, etc. is all marketing hype. 

Join the real world and experiment with only HPS on one garden and only MH on another. 

UB


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## born2killspam (Feb 26, 2009)

I've done that, and found the buds grow a bit differently.. MH yielded lighter, but probably nicer buds.. HPS were denser, but not quite as aromatic.. HPS yield was about 1.25x heavier..
It played out roughly the same way with NL5 and Seedsman's Skunk1.. Most of the time I ran both types above the same table..


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