Lighting and Photosynthesis Facts

[Guest]

1 foot candle = 1 lumen / square foot
Noontime Tropical Sun at sea level = approximately 10,000 foot candles
100 watts of HPS roughly = 9300 lumens
100 watts of MH roughly = 9000 lumens
100 watts of CF roughly = 7000 lumens

The MH light spectrum is strongest between 420 and 510 nanometers.
The HPS light spectrum is strongest between 560 and 625 nanometers.
The average Compact Fluorescent spectrum peaks at 425, 475, and between 550 and 640 nanometers.

Peak energy absorption by chlorophyll takes place between 400 and 475 nanometers, and between 640 and 700 nanometers.

 

[bartender187]

Re: Lighting and Photosynthesis Facts

The MH light spectrum is strongest between 420 and 510 nanometers.

Haha..

bartender187

So theres not light our currently that has wavelengths between 640-700? It would be nice to see how a canabis plant would react to those wavelengths.

 

[Guest]

that part of the spectrum is covered... just not by the peak output...
Some horti. bulbs have slightly different peaks... if anyone knows the spectrum output of some common horti. bulbs feel free to post up...

 

[Einsteinguy]

Hortilux Eye

Hortilux Eye

Here is info on Bulb I use,
It is a Enhanced Spectrum HPS Grow Lamp
Hortilux Super HPS EN.
It has more Blue Spectrum 400-520 than normal HPS lamps

Einstein

 

[Fuzzy&Sauce BBG]

Grat3fulH3ad... Nice info... Here some more...

Hi
Einsteinguy


I Guess I need too show off my spec's too...

It's a Solar Max 1000 SUPERHPS..

FLOWERING
A maturing plant has dramatically different needs than a younger plant. As plants approach maturity they require less "Blue Light" and depend more upon radiation from the "Red" portion of the spectrum between 610 nm -
720 nm.
Now is the time to utilize the superior "Red Light" output of the SolarMax HPS lamp. The SolarMax HPS lamps have been engineered to constantly deliver 10% more targeted "Red Light" energy to the maturing plant to promote aggressive flowering.

FOR STRONGER, HEALTHIER, BIGGER PLANTS

In all stages of plant growth, plants need spectral energy (light) between 400 nm - 700 nm. This is technically known as "Photosynthetically Active Radiation" or "PAR".


VEGETATIVE
In younger plants it is the region between 380 nm - 520 nm that is the most crucial. This region is commonly referred to as "Blue Light".
SolarMax Metal Halide lamps are specifically designed to deliver "Blue Light" frequency in the PAR range to your plants - unlike conventional MH lamps. In fact SolarMax lamps deliver 30% more "nutritious" light radiation than standard lamps. The result - more vigorous, vegetative growth and stronger roots during the important early stages of a plant's development.

LAMPS TUNED FOR PLANTS!
SOLARMAX lamps are specifically designed for horticultural applications. ISO certified engineering and manufacturing processes assure high quality and optimized performance.
SOLARMAX grow lamps are designed with the grower in mind.

Reduces lamp sizes fit most horticultural lighting fixtures. Custom tailored spectral distributions. HIGHEST OUTPUT. All SOLARMAX lamps carry a full ONE YEAR WARRANTY



Here what you need for MAX Growth for VEG & Flower

These combined spectal distributions provide all the light engery needed for your plants!

Sauce

 

[Fuzzy&Sauce BBG]

I forgot...

I forgot...

Oh.. I forgot... Solar Max also has the highest PAR in today's lights... I think it is 450 are 480par.. I think.. I will have to look it up...



Sauce

 

[I.M. Boggled]

Bumpen up this ye olde thread

Bumpen up this ye olde thread

and adding a couple links.

Lumens and lux and PAR, oh my!

PAR figures are never quoted because they depend on the detailed illumination geometry, which varies from setup to setup.

The standard measure that quantifies the energy available for photosynthesis is
"Photosynthetic Active Radiation"
(aka "Photosynthetic Available Radiation") or PAR.

Contrary to the lumen measure that takes into account the human eye response, PAR is an unweighted measure.
It accounts with equal weight for all the output a light source emits in the wavelength range between 400 and 700 nm.
PAR also differs from the lumen in the fact that it is not a direct measure of energy.
It is expressed in "number of photons per second", whose relationship with "energy per second" (power) is intermediated by the spectral curve of the light source.
One cannot be directly converted into the other without the spectral curve.

The reason for expressing PAR in number of photons instead of energy units is that the photosynthesis reaction takes place when a photon is absorbed by the plant, no matter what the photon's wavelength (or energy) is (provided it lies in the range between 400 and 700 nm).

again, for clarity:
The reason for expressing PAR in number of photons instead of energy units is that the photosynthesis reaction takes place when a photon is absorbed by the plant, no matter what the photon's wavelength is.
http://www.icmag.com/ic/showthread.php?t=17118&highlight=par

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Understanding Transpiration and Photosynthesis ( fyi )
http://www.icmag.com/ic/showthread.php?t=6913

IMB

 

[Grat3fulh3ad]

Wow that is old... great bump boggled...

 

[Guest]

and adding a couple links.

Lumens and lux and PAR, oh my!




again, for clarity:
The reason for expressing PAR in number of photons instead of energy units is that the photosynthesis reaction takes place when a photon is absorbed by the plant, no matter what the photon's wavelength is.
http://www.icmag.com/ic/showthread.php?t=17118&highlight=par

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Understanding Transpiration and Photosynthesis ( fyi )
http://www.icmag.com/ic/showthread.php?t=6913

IMB

good info

 

[Grat3fulh3ad]

an
again, for clarity:
The reason for expressing PAR in number of photons instead of energy units is that the photosynthesis reaction takes place when a photon is absorbed by the plant, no matter what the photon's wavelength is.
http://www.icmag.com/ic/showthread.php?t=17118&highlight=par

you can slam photons of the wrong wavelength against chlorophyl molecules all day long without directly photosynthesizing, photons with wavelengths around 500 nanometers are reflected by chlorophyll, not absorbed by it.

wavelength matters very much, and outside of specific wavelengths accessory pigments have to capture the energy from the photon and transfer that energy (at a net loss) to the chlorophyll. Also photons with shorter wavelengths carry more energy.

Also of note... The term is PAR... Photosynthetically Active Radiation... So, even though it is measured in terms of number of photons per second, every photon striking the leaf is not part of the measurement, ONLY the photosynthetically active wavelength photons... Your assumption that wavelength is irrelevant, is based on a misinterpretation of what you posted.

 

[yukino_asano]

This thread rules. Thanks for posting.

 

[knna]

you can slam photons of the wrong wavelength against chlorophyl molecules all day long without directly photosynthesizing, photons with wavelengths around 500 nanometers are reflected by chlorophyll, not absorbed by it.

wavelength matters very much, and outside of specific wavelengths accessory pigments have to capture the energy from the photon and transfer that energy (at a net loss) to the chlorophyll. Also photons with shorter wavelengths carry more energy.

Also of note... The term is PAR... Photosynthetically Active Radiation... So, even though it is measured in terms of number of photons per second, every photon striking the leaf is not part of the measurement, ONLY the photosynthetically active wavelength photons... Your assumption that wavelength is irrelevant, is based on a misinterpretation of what you posted.

PAR is defined precisely for the range of wavelenghts used actively for photosynthesis, mostly caracterized as the 400-700nm range (wich aditionally, is pretty similar to human's perception window). PAR only takes account of photons in that range, and all of them (any wavelenght between 400-700nm) counts.

Although there is differences on how each wavelenght in this range promotes photosynthesis, these differences are generally relatively small. Max difference in this range is about half the efficacy (between max photosynthetic efficacy and minimun, respectively 670nm and 550nm). For wide spectrum lamps (all except leds and LPS) differences are lower, most lamps used for growing ranges from 75 to 85% efficcacy related to 100% at 670nm.

This difference of efficacy due to wavelenght is way lower than the differences in efficiency (photons emited per watt consumed) between different bulbs. So due that the total amount of PAR photons is the best sigle parameter to determine the efficacy of a bulb for growing. Wavelenght isnt irrelevant, but its a lot less important than most people tend to think.

Anyway, the efficacy of a bulb for growing is determined by the mix of two factors: PAR photons emited (per watt) and spectrum. But the baseline is the total amount of PAR photons, wich is corrected by the spectrum efficacy.

Spectrum efficacy is determined by two factors, too: ability to promote photosynthesis of each wavelenght and how much photons of each wavelenght are absorbed by plants.

Photon's absortion by plants is pretty high for blue (430-490nm) and red (630-700nm) photons, over 90% at moderate irradiances (concentration of light at plants: PAR uE/m2; uE=micromol of photons), while its lower for other wavelenghts, specially green (around 550nm). Lower not mean 0, as green photons are still well absorbed, at a minimun of around 75% for cannabis.

Efficacy promoting photosynthesis of absorbed photons is almost flat for shorter wavelenghts (400-565nm), and raising from that point up the 670nm max. From 610 to 680nm, efficacy of photons is the highest.

If you want detailed info about plants lighting, check the link on the thread linked by I.M. Boggled, this NASA workshop and this external thread, wich quantifies all those parameters for cannabis.

Peace, knna

 

[Grat3fulh3ad]

PAR is defined precisely for the range of wavelenghts used actively for photosynthesis, mostly caracterized as the 400-700nm range (wich aditionally, is pretty similar to human's perception window). PAR only takes account of photons in that range, and all of them (any wavelenght between 400-700nm) counts.

Although there is differences on how each wavelenght in this range promotes photosynthesis, these differences are generally relatively small. Max difference in this range is about half the efficacy (between max photosynthetic efficacy and minimun, respectively 670nm and 550nm). For wide spectrum lamps (all except leds and LPS) differences are lower, most lamps used for growing ranges from 75 to 85% efficcacy related to 100% at 670nm.

This difference of efficacy due to wavelenght is way lower than the differences in efficiency (photons emited per watt consumed) between different bulbs. So due that the total amount of PAR photons is the best sigle parameter to determine the efficacy of a bulb for growing. Wavelenght isnt irrelevant, but its a lot less important than most people tend to think.

Anyway, the efficacy of a bulb for growing is determined by the mix of two factors: PAR photons emited (per watt) and spectrum. But the baseline is the total amount of PAR photons, wich is corrected by the spectrum efficacy.

Spectrum efficacy is determined by two factors, too: ability to promote photosynthesis of each wavelenght and how much photons of each wavelenght are absorbed by plants.

Photon's absortion by plants is pretty high for blue (430-490nm) and red (630-700nm) photons, over 90% at moderate irradiances (concentration of light at plants: PAR uE/m2; uE=micromol of photons), while its lower for other wavelenghts, specially green (around 550nm). Lower not mean 0, as green photons are still well absorbed, at a minimun of around 75% for cannabis.

Efficacy promoting photosynthesis of absorbed photons is almost flat for shorter wavelenghts (400-565nm), and raising from that point up the 670nm max. From 610 to 680nm, efficacy of photons is the highest.

If you want detailed info about plants lighting, check the link on the thread linked by I.M. Boggled, this NASA workshop and this external thread, wich quantifies all those parameters for cannabis.

Peace, knna

So, this is wrong?



Photons of wavelengths between 500 and 600 reflect from chlorophyll.
Period.
90% of photosynthetic activity takes place in the narrow bands I've already stated. Outside of those bands, other chemicals have to transmit the energy and there is a loss in efficiency. Just because a photon can be absorbed by a plant does not make it cost effective to produce that color photon when compared to the net gain from adding that wavelength to the spectrum your garden is exposed to.

 

[Grat3fulh3ad]

Or... how about this one...
You can raise cannabis very well with absolutely no green photons at all.
With only green photons, cannabis dies.
'nuff said about the usefulness of green photons.

 

[knna]

So, this is wrong?



Photons of wavelengths between 500 and 600 reflect from chlorophyll.
Period.
90% of photosynthetic activity takes place in the narrow bands I've already stated.
Period.

Before answering that way you should inform yourself of your sources of info and what it means.

What you posted is a graph of chorophills absorbance in lab, wich is anything but representative of how plants photosyntethize. If you had read some of the links i posted, you had realized it.

Before answering so drastic, check the studies about alive plants photosynthesis and then talk.

BTW, the most complete studies about were performed by Inada and McCree on the 70s. Their results are widely accepted as correct for all botanist, replicated numerous times and detailed for specific vegetal species.

For example, the MC Cree curve shows the amount of photosynthesis (O2 delivered or CO2 consumed) per absorbed photons per unit energy:



The Inada curve shows the net photosynthesis per unit energy:




About absorbance of photons depending of its wavelenght, we have avalaible very detailed studies over cannabis courtesy of US Goverment (they like to detect it from air, you know, so they need very precise data about), performed over several strains of cannabis. I post just one of their graphs, so you can take an idea of how cannabis absorb light:

 

[knna]

Or... how about this one...
You can raise cannabis very well with absolutely no green photons at all.
With only green photons, cannabis dies.
'nuff said about the usefulness of green photons.

Hmmmm...have you checked it?

I havent, but i know cannabis grows below LPS, wich is monochromatic at 589nm (yellow), close to 555nm of green light.

Anyway, most plants grow better receiving light along the full PAR range, being best combinations specie's dependent. Read this article about this topic and realize things in real live are way more complex than you think:
OPTIMIZATION OF LAMP SPECTRUM FOR VEGETABLE GROWTH

Peace and good growing

 

[Grat3fulh3ad]

Even with that all being true,
Light at around 500 nm is used the least efficiently, and if that were the only lighting a plant got it would die. Regardless of those facts, a plant will thrive equally well with or without photons in the green portion of the spectrum. But will not thrive equally well eliminating the red and blue portions of the spectrum. Sure plants can use (less efficiently) those wavelengths between 500 and 600, but they do not need them.

Also, the charts you are using simply are a measure of absorption based on the percentage of change in wavelength, and simply chart efficiency of absorption of a particular wavelength. They do not say anything at all about how the plant uses that radiation or how efficiently that radiation is transmitted into photosynthetic energy.

Photosynthesis takes place in chlorophyll. Therefore the radiation which directly affects the chlorophyll is most efficiently used. Other wavelengths of radiation act on other chemicals, carotenoids, phycoerythrin and phycocyanin. These chemicals absorb a photon and transmit a portion of the energy to the chlorophyll.


The radiation which acts on these chemicals, while absorbed by the plant at only slightly reduced efficiency, further looses its effective impact in the transfer.

The charts which show how effectively radiation is absorbed, do nothing to show how radiation is utilized to build the plant.

If one is analyzing the cost effectiveness of producing a photon, I maintain it is more efficient to produce the photons which do the lion's share of the good.

 

[Grat3fulh3ad]

Hmmmm...have you checked it?

I havent, but i know cannabis grows below LPS, wich is monochromatic at 589nm (yellow), close to 555nm of green light.

Anyway, most plants grow better receiving light along the full PAR range, being best combinations specie's dependent. Read this article about this topic and realize things in real live are way more complex than you think:
OPTIMIZATION OF LAMP SPECTRUM FOR VEGETABLE GROWTH

Peace and good growing

The thing I find most interesting in the paper you linked to, is that the ideal ratio of irradiance in the three PAR ranges was so vastly different for tomato and cucumber...


2 blue:4yellow/green:4red in cucumbers

and

1blue:1.5yellow/green:7.5red in the tomatoes

but across the charts, the one aspect of range of PAR which had the greatest effect was the red (600-700nm) range...

What would really be interesting would be to see the same charts for cannabis, but to better gauge effect there should be three charts in which only one PAR range varies in each chart...



**EDIT** also of note... LPS lighting is nearly monochromatic, averaving 589, but actually ranges from just below 580 to nearly 600.

 

[messn'n'gommin']

That the carotenoids capture photons in the green and yellow wavelengths to make them available to the chlorophyls at less than 100% efficiency, is a given. But, the assertion that it is not cost effective for the carotenoids to do so, contradicts natures aversion for wasting energy on non-productive behavior. If there is no benefit to be derived from a specific response then that response is either evolved away or survival becomes less likely. Four aspects of lighting in a controlled environment is quality, intensity, timing, and duration. Can someone grow vegetable matter with lights in either, primarily, red or blue? Sure! It was done yesterday, it will be done again tomorrow. But, restricting the quality of light can only hamper growth not improve on naturally evolved photosynthetic responses, and that includes UVR and IR.

Namaste, mess

 

[Grat3fulh3ad]

Noone is talking about 'restricting light'... I'm only talking about the efficiency of generating light... Is it worth the electricity dollar to generate green photons, when the same dollar could be spent generating more useful light? Is not a dollar spent generating the most efficiently used portions of the spectrum?

Any of you who think it is only about number of photons, and nothing about spectrum need to try growing with mercury vapor lights side by side against growing with proper lights. That should easily prove that not all photons are created equal.

p.s. If you find a lamp that provides all the forms radiation which involve photosynthetic response including uv and ir... please let us all know...