LED Lights Used in Plant Growth Experiments for Deep Space Missions

Discussion in 'Planted Tank Equipment' started by Greystoke, Sep 13, 2012.

  1. Greystoke
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    Greystoke Specialist

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    I came across this article recently: http://www.nasa.gov/centers/kennedy/home/plant_growth.htmlLED Lights Used in Plant Growth Experiments for Deep Space Missions[/url]

    It does NOT provide much useful information other than the fact that the plants are grown under a combination of RED and BLUE LEDs. (our famous RED/BLUE ratio ?)
    (Perhaps these people should have talked to us first :thumbsup:)
     
  2. tyronegenade
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    There have been some experiments on orchids using combinations of red and blue LEDs. I forget what the ideal ratio was but it doesn't matter much to us. We want an aesthetically pleasing tank which needs more than red and blue LEDs.
     
  3. Greystoke
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    But of course . . . but that doesn't take away the necessity to maintain a suitable RED/Blue ratio.
    (or does - besides the ratio - the absolute content of the RED and the BLUE make a difference? I suspect it does.)
     
  4. tyronegenade
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    Well, we have the % R, B and Y light in your data sheet, and we know just how many quanta of light is emitted per wavelength so once can calculate that from your database.

    I did some (inaccurate math) where I multiplied the % B by the average PAR per lamp and added it to the % R multiply by the PAR and got the following ranking:
    sunlight: 0.8
    GMANN PWRCHROME Aquaflora T5HO: 0.90
    Arcadia Plant Pro T8: 0.77
    GMANN PWRCHROME Midday T5HO: 0.77
    Sylvania 865 T8: 0.75
    Lumilux 880 Skywhite T5: 0.75
    Hagen Life-Glo T5HO: 0.71
    SERA daylight brilliant T8: 0.71
    Sylvania AQUASTAR T5: 0.70
    Lumilux 880 Skywhite T8: 0.70
    Hagen Life-Glo T8 0.70:
    Lumilux 830 Warm White T5HE: 0.68
    Philips TL-D 90 De Luxe 965 T8: 0.67
    Philips AQUARELLE T8: 0.67
    Arcadia Original Tropical T8: 0.66
    Lumilux 840 Cool White T5HE: 0.66
    BOYU Floral Light T8: 0.65
    Lumilux 865 Cool Daylight T8: 0.62
    Osram Natura T8: 0.60
    Lumilux 830 Warm White T5HO: 0.59
    Lumilux 830 Warm White T8: 0.59
    Sylvania GRO-LUX: 0.59

    How interesting that some of our favourite tubes group together! Seems the amount of R and B is important.
     
  5. Greystoke
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    Greystoke Specialist

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    I'll have to get my head around this one first. :scratch:
     
  6. Greystoke
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    Let's see now,
    % R x PAR is a subtotal of PAR. Let's call it PAR[sub]red[/sub], and in a similar fashion you get: PAR[sub]blue[/sub]
    ADD them together, you should get something that is probably related to PUR, but it's more directly related to the absolute amounts of RED and BLUE in the spectrum, which are required to get good growth.

    Very clever :thumbsup: So what should we call this?
     
  7. tyronegenade
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    tyronegenade Specialist

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    I'm not sure.

    I think a better measure would be to take the W/nm on your charts and integrate them for the blue and red ranges and then add these.

    We can calculate the number of photons of red and blue light by:
    1. multiplying Plank's constant by the speed of light (h x c)
    2. Dividing this by the wavelength (HC/λ)
    3. Dividing the wattage for each nm band by the answer from (2) (Wλ/HC)

    The important point is not the %R or B but exactly how many particles of blue (300--400 nm) and red (600--700 nm) light are emitted by the lamp. It is the quanta of light which the plants use.
     
  8. R.C.
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  9. Greystoke
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    @Tyrone: I can do those converts, and I'll give you a shout when ready.

    @R.C.: Indeed, but they say that the old Blue LEDs weren't very good. They seem to be a lot more successful these days.
    I am interested in this development to see if we can get more info about the R & B quantities for our own benefit. At this point in time all we have is the R/B-ratio (≈0.92), but there must be more to it.
     

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