Thinking of a new light ..

[PetFlora]

My head hurts now

It would seem so, but to me that suggests there is something more than just umoles at play

 

[stardustsailor]

The answer is no.....
Actually ,we are both having lights that emit light of 25W radiant power ...

Pets light has ~112 umol/sec radiant photon flux ....
Mine has ~ 122 umols/sec radiant photon flux

Pet's light is covering an chlorophyll absorbance band ,that is not that much absorbed like the red and blue light are ...
But it emits photons that are used more efficiently from the photosynthetic systems ,regarding the utilisation of photon
energy and the transformance to matter ...

That band has highest Relative Quantum Efficiency ....

Let's put a ' constant ' here ..
We're gonna need it ...

For every molecule of CO2 absorbed and processed into carbonhydrates (or reverse ..For every O2 released ....Same thing ) ...100% of RQE is 8 photons ...( it will be even easier if we lower the standarts ..To be more sure ..10 photons ..
100% relative quantum efficiency ,for the stoner SDS, means that 10 of those photons are used to process a molecule of CO2 into CHO ....Sugar ...Energy & Matter ...
Lower efficiency means ,that more photons are needed to process a molecule of CO2 ....

How's that ?

Up till now ....

Same wattage ...
Different photon flux ...
Different total RQE of radiant light
Different total absorption of radiant light

And one constant ....

Oh ..
I got shit for brains ....

 

[stardustsailor]

Before I continue further ...
The umol math ,that this unit is relative upon ...
Is not based on Gaussian (and math ...) curve ,like the 'lumens vs Watt' conversion is ...
But linear ..
Radiometric ...




And the linear graph is this one :


As you can see ...
1 Watt of radiant light :
@ 700nm = ~6umol/sec
@600nm = ~5 umol/sec
@ 475 nm =~4 umol/sec ....


And here's the linear relativity of umols to wavelengths (or frequencies if you prefer )

 

[stardustsailor]

So 1000umols/sec with ....some 'other' 1000umols/sec ....
Can have ...

Quite a .....huge difference ...
In way many aspects ...( wls ratio: radiant power: RQE :absorption.......At least .....)
Which this fact alone ..
Renders ...
Umols/sec ...
Totally useless ...
Wayyyy relative unit ...
Can mean a lot of things ...
Those 1000umols may have powerful growing abilities or completely
no abilities at all ..or detrimental ..
( 2000 umols/sec of 517nm cyan-green light ..How's that sounding ? )

At least for the moment,being ....

Any ........comments ?

 

[MrFlux]

umol/J is the key. How much usable photons can you make with one Joule of energy.

 

[stardustsailor]

Well ..At least for output radiant power we still have the good ol' Joule/sec aka Watt .....
It's a starting point ...

Now ...
Back to light's ...misty fields ....


We have also a ' constant ' ..
100% of RQE is 10 photons ( aka quanta ) ....

RQE is also a constant byitself for every nanometer of PAR ...
Every single wl has it's own RQE .
A unitless constant ,ranging from 0 to 1 ...
( 0% -100% ) ...

And pretty much ...
we have an analytical table ...
Pretty useful
Averaged -normalised from specimen of over 2o different species of higher plants ...
Which actually had ,pretty much the same RQE / nm ....So ...
RQE is another ' constant' ....

 

[stardustsailor]

umol/J is the key. How much usable photons can you make with one Joule of energy.

????
Here's the 'juice' ..
Com' on ...
Continue ...
In what way usable ?

Very complex

1st level : Photosynthesis utilisation experimenta light GROWTH EFFICIENT ENERGY/NM unit ....

Total Radiant Power (P)
*
Spectral absorption % / nm (RSA)
*
RQE % / nm (RQE)
/
10 quanta per CO2 ....
-
(Photoinhibition/Photo saturation /photo degradation factor per nm/Watt (LDF)
*
Total illumination duration(T) )

( (P*RSA*RQE/10 - LDF)*T ) / nm

Appen:
Power
RelativeSpectralAbsorption
RelativeQuantaEfficiency
LightDegradationFactor
Time

At least.....

2nd level ....Photomorphogenesis and direct/indirect effects on Photosynthesis ..
aka
Go back to 1st level after digging to some really thick science bio- math shit...
(which I'm digging ...shit for brains ..shit digging ...)

 

[guod]

umol/J is the key. How much usable photons can you make with one Joule of energy.

usable photons // unkown term or not specified
spectrum or wavelength missing
....
misson impossible

 

[stardustsailor]

Hey...
Yes ...
I can go further only inside my mind if you like ...
But ...
You know what ....
Actually ,the only useful and meaningful unit at the moment is radiant light power ...
With that in hand,we also know/can calculate the electrical efficiency of a light / led ....

The real stuff ...
The growth efficiency ...
It's another ...'unit' ...

It needs many brains ,around here to work ,to agree ,to R&D about it ...
To search further ...
As we all do here ...
In fact ..
The led section here ...
The level of R&D of it's members ,was always far beyond ....
Even from many brands or actual science reports ...


I threw an idea to the table ...
A thought ...
A truth...

My mind ...
Your Arena ...
Enter ....

 

[stardustsailor]

usable photons // unkown term or not specified
spectrum or wavelength missing
....
misson impossible

Spectrum or wavelength ,there every where ...
RelativeSpectralAbsorption
RelativeQuantaEfficiency
LightDegradationFactor

Complex math needed..Guod needed ...
Math for emission curve.
You can make it .
I can't...
I'm not good at (higher) maths.
You're .
Spreadsheet...
You can !


If anyone can ,that is you ,you ......

Nothing's impossimble.
Nothin'.

 

[stardustsailor]

usable photons // unkown term or not specified
spectrum or wavelength missing
....
misson impossible

Make one !


Others who invent units ,what more special have than you or me ,that we do not have ?
Meat ,bones,brains ...
Same as we are ...

Work,is needed ....
Team-work !!!

 

[stardustsailor]

More brain mass ,brother ,in action ..

 

[MrFlux]

Usable to me is anything between 400-700nm. As a second consideration I look at the amount of blue (using 420-480nm as blue). This is a very simple model. The attraction is that it can actually be used for comparisons and decisions.

 

[stardustsailor]

I'm tired for today ...
Searching is a part of my life ...
Gives me purpose ..
I'm not competing Guod,PSUAGRO,Fran or any other else here ...
I'm here 'cause ....

I feel alive ...

Guod ...We can do it ...
Easily ...
All of us ...
We have to set some 'agreements ' or ' common accepted facts' ...
And we need an analytical table of relative absorption (* a general one ..that;s one of the kind of 'agreements' we have to set ..)

Of alive plants ....
Not of solutions ....

 

[stardustsailor]

Usable to me is anything between 400-700nm. As a second consideration I look at the amount of blue (using 420-480nm as blue). This is a very simple model. The attraction is that it can actually be used for comparisons and decisions.

It's not that simple ...
We 've to leave at present photomorphogenesis outside of the math...

The idea is to 'find' an ideal .....spectrum ...vs power ...graph ...of the most efficiently (possibly ) used light for photosynthesis,alone ....
With some constants taken into account ...
Known constants ,thay we know and neglect ....
And never talk about ..And they are of the most importance ones ...

And then start talking about the ideal veg-clone-mum-flower -etc specific spectrum ..
Oriented ..Targeted....


Firstly the basic ideal ...
The ideal ( most efficient) basic light fuel mixture ....

And we 've what we need ,in order to do that .....
Ok ..
More or less...
We can find more ....
We know( & can search further) the exact the absorbance / reflectance of mj plants ....

More factors ...
Regarding use and effects of light ...


We're taking things way ahead ,anyhow ...
All of us here ...
Sometimes ,someone's got to push a bit or start making noise ...
But ..

We're doing some pretty good shit,all of us ...
Regarding Leds ...
Pioneers ...


I'm fucking high .....

And tired...

 

[stardustsailor]

Action spectrum of plants and RGB output

Not all incident radiation is absorbed by actively photosynthesizing leaves. Depending on wavelength,
light incident on a leaf may be reflected, transmitted through the leaf or absorbed by the light harvesting complex to drive the light reactions. The proportion of light absorbed at any particular wavelength varies between and within species, and frequently between individual leaves in a plant canopy, dependent on canopy position
and the history of the leaf. Absorbed light drives the light reactions and variations in the amount of absorbed light
alter the overall carbon assimilation rate. For many higher plants, much of the photosynthetically active radiation (light with wavelengths between 400 – 700 nm) is absorbed with peaks near the absorption peaks of
chlorophyll a and b ( a: 430 and 660 nm; b: 455 and 645 nm). As a result, light with wavelengths in the red and blue region of the spectrum typically drive photosynthesis more efficiently than other wavelengths. On a
quanta basis, red and blue often drive the same amount of photosynthesis since the extra energy in blue light is quenched by non-photochemical processes (e.g. heat; Blankenship, 2002). However, because other
wavelengths of light are absorbed and are equally capable of driving photosynthesis, it is important to not only describe an absorption spectrum, but also the photosynthetic action spectrum for the absorbed light.
Action spectra describe the amount of CO2-fixed or O2-released at a particular wave-length across the absorption spectrum for a leaf. As is the case for absorption spectra,action spectra vary greatly between species

(McCree, 1972).

For many C3species, there is greater assimilation when plants are
illuminated with red light and to a lesser extent blue light than when illuminated with green light.



The 6400-18 Red, Green, Blue (RGB) Light Source is a composite LED source comprised
of multiple diodes embedded within a tile.

The LED wavelength peaks of this commercially available tile are 460, 522 and 635±5 nm,
corresponding to light in the blue, green and red regions of the light spectrum respectively.
Apparent white light is achieved by providing equal quanta of each LED color.
This is not a broad-spectrum white such as solar radiation, but rather it is the composite
of all three LED colors. The LED tile used in the RGB Light Source achieves white light†levels of 2000μmol m-2s-1with a spatial uniformity of±10% over 90% of the output area.









Plant response with RGB output



Each LED color in the RGB Light Source can be controlled independently.
Due to this independence of control, one natural experiment is to examine the photosynthetic
response to each LED color.

Light responses at each color were measured on 6 to 8 week old Arabidopsis thaliana plants using the
6400-17 Whole Plant Arabidopsis Chamber.
A combination of clay capping of the planting medium and slight overpressure were used to suppress CO2 flux from the planting medium (see Application Note #4: Using the Whole Plant Arabidopsis Chamber Effectively). Photosynthetic responses were measured at 600μmol mol-1CO2 and 50 – 70% relative humidity at approximately 25°C. The plants were light acclimated under 600 μmol m-2s-1white light until photosynthesis and transpiration were at steady state.
Light responses were measured from high to low in a single color chosen at random. Plants were again acclimated to 600μmol m-2s-1 white light and the response was then repeated with a different color.The photosynthetic responses to light for the different colored LEDs were similar (Figure 1).

Based on the action spectrum discussed above, red light was expected to have the greatest assimilation rate at each light intensity and green would produce lower assimilation rates.



However, there was no differencebetween the photosynthetic responses to each of thecolors, which was surprising based on previous studies .............(McCree, 1972).......was measured on single leaves from 6 to 8 week old plants. Chamber environmental conditions were as noted above. There were no significant differences in the photosynthetic response under different colored light (Figure 2A). The absorbed light was calculated from absorption spectra for Arabidopsis (see below).The quantum yield was calculated for each color and there was no difference in the rates between colors(Figure 2B)




To eliminate any enhanced assimilation effect o fgreater light absorption by the overlapping leaves of
the rosette, photosynthetic responses to different colors of light were measured on individual leaves.

The RGB Light Source was placed over a standard clear-topped2×3 cm chamber and the photosynthetic assimilation
The leaf-level photosynthetic light response of field-grown soybean leaves was also investigated. Individual soybean (cv.U98-311442) leaves were mea-sured following the same protocol with a 2×3 stan-dard chamber except that [CO2
] was controlled at 380μmol mol-1and light intensities were higher. The different light colors drove photosynthesis at similar assimilation rates (Figure 3)
The similarity in photosynthetic responses at different colors of light for the two species suggested that the absorption should be similar.
The absorption spectra of Arabidopsis and soybean were measured from 400to 700 nm in 1 nm increments using a spectroradiometer (LI-1800 Portable Spectroradiometer, LI-CORBiosciences, Lincoln, NE) and integrating sphere
(1800-12S External Integrating Sphere, LI-COR Bio-sciences). Arabidopsis absorption was greatest in the
blue and red wavelengths and was 30% lower in thegreen wavelengths (Figure 4). Soybean had much
stronger absorption across all wavelengths and did not have such a large decrease in the green wavelengths

However, the LED output in combination with the absorption spectra show that light absorption was
similar for each LED color type.

With similar light absorption, the lack of a difference in the photosynthetic responses to color is clear.

For both Arabidopsis and soybean, the red LED output (peak 635 nm) is not centered on the absorption peak (approximately 680nm) .

Additionally, there is substantial absorption of the green LED as it overlaps into the blue and red. The calculated weighted absorption (αw) is the product of the leaf absorption (α) and the LED quantum output(Q) from wavelengths (λ) 400 to 700 nm and is normalized to (see pdf )

The αwfor soybean differed by only 6% and the difference between green and red αw
was only 9% forArabidopsis (Table 1).
Although there is a larger difference between the green and blue LEDs (23%),
significant overlap in output spectra and the lower efficiency of blue light conversion to reducing power
decreased the effective difference in αw between these colors.

The lack of significant differences in absorbed light for the different LED colors resulted in similar photosynthetic rates
Conclusion

The three colored LEDs’ output spectra are absorbed by plant species differently.

Because of plants’ ability to capture much of the PAR spectrum and the bandwidth of the LED output, most of the light striking the leaf is absorbed and used in photosynthesis.

When examining the photosynthetic response to light, it is important to normalize the light to the plant’s absorption.
....................................................................................................................









When used in concert, the three LED colors give an apparent white light well suited for many photosynthesis studies.
The 6400-18 RGB Light Source delivers white light that is near solar irradiance levels without the heat generation associated with broad spectrum sources.


http://www.licor.com/env/pdf/photosynthesis/AppNote5.pdf

 

[Mohican]

I can take over.

This subject is related and makes me wonder how high altitude spectra differ from sea-level spectra.

The ground level spectrum also depends on how far the sun's radiation must pass through the atmosphere. Elevation is one factor. Denver has a mile (1.6 km) less atmosphere above it than does Washington, and the impact of the time of year on solar angle is important, but the most significant changes are due to the earth's rotation. At any location, the length of the path the radiation must take to reach ground level changes as the day progresses. So not only are there the obvious intensity changes in ground solar radiation level during the day, going to zero at night, but the spectrum of the radiation changes through each day because of the changing absorption and scattering path length.

With the sun overhead, direct radiation that reaches the ground passes straight through the entire atmosphere, all of the air mass, overhead. We call this radiation "Air Mass 1 Direct" (AM 1D) radiation, and for standardization purposes we use a sea level reference site. The global radiation with the sun overhead is similarly called "Air Mass 1 Global" (AM 1G) radiation. Because it passes through no air mass, the extraterrestrial spectrum is called the "Air Mass 0" spectrum.


So my next question is - what is the exact spectrum seen by a plant from sunlight at sea level?

Can't find a good example but I did find this chart of photosynthesis by different spectra:




On this site: http://plantphys.info/plant_biology/photopart.shtml


I am on a knowledge hunt now!

 

[Mohican]

More great basic info (terpene involvement!):

http://plantphys.info/plant_physiology/light.shtml

 

[stardustsailor]

PSU .....

http://www.licor.com/env/pdf/photosynthesis/arabidopsis-brochure.pdf

http://www.licor.com/env/products/photosynthesis/chambers/6400-18.html

Here's some pretty serious scientific testing toys ...
(Not grow lights ....)
....

Truth Analysers ....

In order to build fine led grow lights ...

Like yours ....

 

[stardustsailor]

Power Consumption : ≤ 45 W at 2000 μmol m-2s-1(white light) at 25°C

(How's that possible ? )



Distance ......



So,that 's how useful are the umols/sec....
And the green light ...
Maybe .....

Who knows ?