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spectral absorption by plant chloroplasts

     I think it is fairly important that when we discuss the light 
     absorption of plants for the purposes of photosynthesis we keep in 
     mind several points:
     1) only light energy (photons) of specific frequencies are absorbed by 
     plant chloroplasts. I don't have information on how wide these 
     absorption bands are or how efficiently plants use them. Highly 
     evolved plants (macrophytes) are able to utilize dozens of spectral 
     bands. My understanding is that there are several pigments which 
     absorb and chemically assist in converting energy for the 
     photosynthesis process. I'm very curious to learn how this works. 
     Perhaps somebody could enlighten us further!?
     2) the terms red, green and so forth are too imprecise to be of much 
     use in technical discussion. These refer to wide bands of frequencies 
     which correspond to human visual responses. These "colors" of light 
     are unique to the human perspective and we should try to avoid making 
     generalizations if we want to be precise.
     3) sunlight is a composite of light radiation of a very wide spectral 
     range. Fluorescent and gas emission type lights emit light radiation 
     in just a few bands. Incandescent lights, while less efficient at 
     energy conversion, have a much wider spectrum. This wider spectrum can 
     be used more effectively by plants than narrow bands which do not 
     correspond to the absorption bands of plant pigments.
     4) points 1 & 3 notwithstanding, plants are able to grow quite 
     satisfactorily using ordinary cool white fluorescents. There is 
     sufficient radiation in the important bands. I don't know if specific 
     types of fluorescent lights are more cost effective for growing plants 
     than others. We do need a balance of light in several spectra in order 
     for us humans to perceive the colors of the plants naturally or as we 
     would under sunlight.
     This is a summary of points that have all been made but I'm hoping to 
     elicit some useful data.
     Q: What are the spectral absorption bands for aquatic plants? Do these 
     bands vary between plant types? Have they been mapped precisely?
     Q: How well do scientists understand the mechanics of light energy 
     conversion with respect to the helper pigments?
     Q: How well do the so called "grow lights" match the spectral needs of 
     aquatic plants? If we value faster growth, are these bulbs a good 
     investment as opposed to simply more wattage? (hint: show the math)
     Steve in Vancouver BC