> We are all aware that usually plants do better with natural sunlight
> than with artificial light.
I am one person, perhaps in the minority, that is not "aware" of this.
That is, I believe that I can grow most plants under artificial lights
and have them look just as good as those grown under sunlight provided
that other growing requirements are met also.
Many different kinds of artificial lighting are available, and the correct
combination can closely approximate the solar spectrum.
> A reasonable explaination for this is sunlight provides a wide
> spectrum of frequencies.
Plants grow well under solar illumination because they've evolved with
it (if you believe Darwin's theory). The details of which frequency
components most influence growth are complicated, and are worthy of a
literature search at the very least.
> ...ideal "black body" radiation provides all frequencies of radiation.
This statement is not complete. Yes, in the ideal case all frequencies
are present. But, they're not present in the same amounts. Energy
radiated by a black body for a given frequency is described nicely by
Planck's law-- a plot of the function resembles a steep hill. The top
of the hill corresponds to the frequency of highest radiated energy.
The frequency at which this peak occurs is a function of black body
temperature, so as the temperature goes up the center frequency goes up
also. I believe that the visible solar spectrum has maximum radiation
in the green.
> The heating of a ceramic rod closely simulates the frequency output of
> such a black body and therefore analagous to an ordinary tungsten
> incandescent light. Yet, most "grow" lights are flourescent.
You'd have to get that ceramic rod awfully hot in order for its radiation
to approximate that of an ordinary tungsten incandescent lamp.
If you know the frequency of maximum radiation of a fluorescent lamp
then you can calculate its effective black body temperature. That won't
tell you much--it's nice that fluorescents give off radiation in the visible
without getting that hot. According to Wien's law, if we assume the center
frequency of a fluorescent is in the green (~600 Tera Hertz) then its
equivalent Kelvin temperature is 5,796 degrees or 5,523 degrees C!
> If anyone could provide any information on the frequencies of light that
> plants utilize the most, I would most appreciate it. I am under the
> impression that it must be in the ultraviolet region.
There was a good article in Scientific American within the past two years
about the details of the chlorophyll-photon interaction. Sorry I don't
remember the precise issue right now; your question prompts me to search
for the issue again.. If I find it then I'll post the information.
Regards,
Perry Malouf