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Old 01-06-2013, 10:29 AM   #16
-Az-
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Default Red to Far Red Ratio

Nick,
what are your thoughts on the red to near red ratio?

i think I read somewhere in can be used as a way to measure PUR.

more importantly, i've just been doing some reading on phytochromes and was interested in this.

"Finally, phytochrome allows plants to detect the spectral quality of light, a form of color vision, by measuring the ratio of Pr to Pfr. When a plant is grown under direct sun, the amounts of red and far-red light are approximately equal, and the ratio of Pr to Pfr in the plant is about 1:1. Should the plant become shaded by another plant, the Pr/Pfr ratio changes dramatically to 5:1 or greater. This is because the shading plant's chlorophyll absorbs much of the red light needed to produce Pfr and absorbs almost none of the far-red light used to produce Pr. For a shade-intolerant plant, this change in Pr/Pfr ratio induces the plant to grow taller, allowing it to grow above the canopy."
McGraw-Hill Encyclopedia of Science and Technology

mmmm
does this mean with 2%far red we should only have equal 660nm.
if we increase both to the 20-40% range would that be detrimental.
maybe a balance. down to 7-15% for both.

what does every one think??
I'd be keen to hear your thoughts Nick.
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