Getting away from PPF for a moment, we were told by a grower that the plants had to be in a dark environment for 12 hours a day.
Btw, a "dark environment" to plants but one visible to cameras and humans alike can be provided by green-only illumination.
Since chlorophyll appears green, therefore it reflects green.
Green spectrum lightning allows workers to keep working during dark periods and is available at grower's marketplaces.
Now if somebody were to replace the security cameras IR led ring with the correct frequency spectrum green leds, that would be a camera that could possibly generate some interest from growers :)
NOTICE: This comment was moved from an existing discussion: Do Cannabis Greenhouses Require 940nm IR Illumination?