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I have a plant on my desk, and it got me to wondering: Can my plant use the light from my monitors to photosynthesize? If so, what light (apart from green light, to a degree) can't plants use to perform photosynthesis?

I know that plants have the photosynthetic pigments to absorb many different wavelengths of light (primarily red and blue) but would there be certain types of light it can't use?

(The specific plant by the way is Schlumbergera truncata)

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Chlorophyll can use a quite broad range of light for photosynthesis, the only range where it is not working is approximately between 500 and 620nm. See this adsorption spectrum of chlorophyll (from the Wikipedia article on Chlorophyll):

enter image description here

The lack of chlorophyll to absorb light between 500 and 620nm (roughly) results in the green color of leafs, because this light is reflected. Besides the wavelength also the energy of the light is important, so plants will grow better in sunlight than in the light of your monitor. This link about the maximum effectiveness of photosynthesis is also interesting.

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    $\begingroup$ I like this image because it also shows why chlorophyll is green. $\endgroup$
    – daniel
    Commented May 8, 2014 at 16:31
  • $\begingroup$ Would I be right to assume, then, that the monitor's red and blue pixels would be useful for the plant, while the green would not? (granted, a monitor produces so much less light than the sun that having it nearby isn't doing much for the plant...just theoretical) $\endgroup$
    – Tim S.
    Commented May 8, 2014 at 17:29
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    $\begingroup$ Theoretical, yes. And this is what special growth lamps for plants do. They leave out parts of the spectrum. The Wikipedia article I linked contains a photo of such an installation. $\endgroup$
    – Chris
    Commented May 8, 2014 at 17:50
  • $\begingroup$ "Besides the wavelength also the energy of the light is important" - wavelength defines the energy of light and vice versa. What you wanted to say was the intensity of light field. $\endgroup$ Commented Dec 27, 2015 at 11:28
  • $\begingroup$ It might also be of use to know that plants 'use' certain wavelengths of light as a sort of sensory input, in addition to providing the photosynth energy . The same can be said for light-dark cycles. Plants know when winter is coming as the days get shorter. today.duke.edu/2015/07/plantlightsensors Phytochrome en.wikipedia.org/wiki/Phytochrome Phototropism en.wikipedia.org/wiki/Phototropism $\endgroup$
    – DonJulian
    Commented Dec 27, 2015 at 14:06

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