Mayor McCheez
New Member
Hi I am currently researching the topic of LED grow lights. I thought I'd share what I've learned so far:
I checked out a few books on the topic of photosynthesis. Chlorophyll a is not the only photosynthetic pigment found in plants (carotenoids, chlorophyll b, etc.) A quick and easy way to check out the TOTAL photosynthesis is to look at a plant's photosynthetic action spectrum. You can run a google image search for this. It will get you a rough idea, but there's more.
Chlorophyll concentrations vary from plant to plant, as well as from strain to strain.
The books I've seen explain how to do a detailed chemical analysis to find the concentrations of each pigment, but doesn't look simple enough to do without a full-blown lab. Though, I have seen devices for sale online which claim to measure chlorophyll a content via light sensors.
In addition, the rate of photosynthesis (essentially the rate of plant growth) can be affected by CO2 levels, temperature, and light irradiance (brightness).
"* At constant temperature, the rate of carbon assimilation varies with irradiance, initially increasing as the irradiance increases. However at higher irradiance this relationship no longer holds and the rate of carbon assimilation reaches a plateau.
* At constant irradiance, the rate of carbon assimilation increases as the temperature is increased over a limited range. This effect is only seen at high irradiance levels. At low irradiance, increasing the temperature has little influence on the rate of carbon assimilation."
-https://en.wikipedia.org/wiki/Photosynthesis#Factors
So, not only do we need to establish general wavelength specs for our lights, but specific experiments conducted on an individual strain will tell us the ideal temperature, CO2, and irradiance.
Here is a good all-purpose plant action spectrum:
Here's my analysis of this spectrum. I'm using this as a general guideline for choosing percentages of each wavelength:
% of my total array - wavelength (nm)
5.7% - 400
6.4% - 414.3
7.0% - 428.6
7.1% - 442.9
6.8% - 457.1
6.1% - 471.4
5.9% - 485.7
5.7% - 500
3.2% - 514.3
2.6% - 528.6
2.1% - 542.9
1.8% - 557.1
1.9% - 571.4
2.1% - 585.7
2.7% - 600
3.1% - 614.3
3.9% - 628.6
5.0% - 642.9
5.6% - 657.1
5.7% - 671.4
6.4% - 685.7
2.1% - 700
0.7% - 714.3
If you guys have a better action spectrum, PLEASE tell me.
Also, does anyone have any info regarding the specific action spectrum for herb?
And maybe you guys know the lumens/candelas/einsteins of photons requirements for the plants? I need more information about how much of each wavelength is required. I have the percentages, but not the specific amounts per plant.
Thanks,
McCheez
I checked out a few books on the topic of photosynthesis. Chlorophyll a is not the only photosynthetic pigment found in plants (carotenoids, chlorophyll b, etc.) A quick and easy way to check out the TOTAL photosynthesis is to look at a plant's photosynthetic action spectrum. You can run a google image search for this. It will get you a rough idea, but there's more.
Chlorophyll concentrations vary from plant to plant, as well as from strain to strain.
The books I've seen explain how to do a detailed chemical analysis to find the concentrations of each pigment, but doesn't look simple enough to do without a full-blown lab. Though, I have seen devices for sale online which claim to measure chlorophyll a content via light sensors.
In addition, the rate of photosynthesis (essentially the rate of plant growth) can be affected by CO2 levels, temperature, and light irradiance (brightness).
"* At constant temperature, the rate of carbon assimilation varies with irradiance, initially increasing as the irradiance increases. However at higher irradiance this relationship no longer holds and the rate of carbon assimilation reaches a plateau.
* At constant irradiance, the rate of carbon assimilation increases as the temperature is increased over a limited range. This effect is only seen at high irradiance levels. At low irradiance, increasing the temperature has little influence on the rate of carbon assimilation."
-https://en.wikipedia.org/wiki/Photosynthesis#Factors
So, not only do we need to establish general wavelength specs for our lights, but specific experiments conducted on an individual strain will tell us the ideal temperature, CO2, and irradiance.
Here is a good all-purpose plant action spectrum:
Here's my analysis of this spectrum. I'm using this as a general guideline for choosing percentages of each wavelength:
% of my total array - wavelength (nm)
5.7% - 400
6.4% - 414.3
7.0% - 428.6
7.1% - 442.9
6.8% - 457.1
6.1% - 471.4
5.9% - 485.7
5.7% - 500
3.2% - 514.3
2.6% - 528.6
2.1% - 542.9
1.8% - 557.1
1.9% - 571.4
2.1% - 585.7
2.7% - 600
3.1% - 614.3
3.9% - 628.6
5.0% - 642.9
5.6% - 657.1
5.7% - 671.4
6.4% - 685.7
2.1% - 700
0.7% - 714.3
If you guys have a better action spectrum, PLEASE tell me.
Also, does anyone have any info regarding the specific action spectrum for herb?
And maybe you guys know the lumens/candelas/einsteins of photons requirements for the plants? I need more information about how much of each wavelength is required. I have the percentages, but not the specific amounts per plant.
Thanks,
McCheez