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I have read a lot of good info regarding the benefits of the blue Action Spectrum. Unfortunality, most of the info is spread across a few threads, forums, web-pages, etc, etc. So I thought it would be a good idea to catalog the effects the blue spectrum light has on plants.
My goal is to list the positives/negatives of the blue and red action spectrum in regards to their interaction with plants*.
*not species/strain specific
Most of the best info I posted below is from this site (MrMistery you are amazing). Please read this for accuracy, am I missing something or should I remove/change something?
Plant Action Spectrum:
Action Spectrum: blue 425-500nm
Action Spectrum: red 650-700nm
PAR range 400-700nm
Blue Action Spectrum (425-500nm):
-preferred by chlorophyll b
-preferred less than, but nearly as much as red by chlorophyll a
-zeitlupe is a blue light receptor*
-phototropin is a blue light receptor*
-cryptochrome is a blue light receptor*
-zeaxanthin is a blue receptive pigment that opens stoma in daylight
-carotenoids absorb blue light and transfer the energy to chlorophyll b (helps offset lower efficiency of blue photon)
-wavelength is shorter and higher in energy, blue photons are absorbed less efficiently (lower action rate due to photons higher energy)
*The blue light receptors do a variety of the following:
mediate blue light-induced phototropism (circadian rhythms), chloroplast re-localization, opening of the stomatal aperture and stimulates proton pumps that drive protons out of the cells which starts off a whole set of reactions; electochemical gradients, osmosis of water, etc.
Red Spectrum (650-700nm):
-enables the conversion of starch into malate which keeps the stomata open.
-preferred by chlorophyll a, although blue is preferred nearly as much by chlorophyll a
-nearly all plants have a higher concentration of chlorophyll a than chlorophyll b
-wavelength is longer and lower in energy, red photons are absorbed more efficiently (higher action rate due to photons lower energy)
a) Does blue light contain the same amount of photons (PPF/PPFD) as red light?
b) What is the 'real world' difference between PPF and PPFD?
c) Are PPF/D and watts directly corralted? Will an increase in watts within an area also increase the amount of photons? As a corollary, could a plant even process the extra photons?
d) From what I've read it is PPF/D within PAR that really matters. So, at this time it seems the most beneficial light source would use the correct level of PPF/D with a focused wavelength ratio; blue to red action spectrum of 70/30. Would this be a fair and accurate statement?
Last edited by bta on Fri Jun 08, 2007 6:19 pm, edited 4 times in total.
just updated a few items:
a) Blue light receptors stimulate proton pumps that drive protons out of the cells which starts off a whole set of reactions; electochemical gradients, osmosis of water, etc.
b) Red light enables the conversion of starch into malate which keeps the stomata open.
c) The most beneficial light source would use the correct level of PPF/D with a focused wavelength ratio; blue to red action spectrum of 70/30. Would this be a fair and accurate statement?
This is fascinating! I'm working to develop a high power LED luminaire for propogation and plant growth to replace the high pressure sodium lamps (and others) commonly used.
LEDs are binned in wavelength groups and I want to get the right mix in a single luminaire in order to provide the best spectral output for plant growth/function.
The advantages are:
no infra red radiation
Can anyone help? I'm looking to run this as a research project in conjunction with a university/learning institution.
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