https://en.wikipedia.org/wiki/Photomorphogenesisen.wikipedia.org/wiki/Photomorphogenesis
In developmental biology, photomorphogenesis is light-mediated development, where plant growth patterns respond to the light spectrum. This is a completely separate process from photosynthesis where light is used as a source of energy. Phytochromes, cryptochromes, and phototropins are photochromic sensory receptors that restrict the photomorphogenic effect of light to the UV-A, UV-B, blue, and red portions of the electromagnetic spectrum.[1]
The photomorphogenesis of plants is often studied by using tightly frequency-controlled light sources to grow the plants. There are at least three stages of plant development where photomorphogenesis occurs: seed germination, seedling development, and the switch from the vegetative to the flowering stage (photoperiodism).[2]
Most research on photomorphogenesis comes from plants, it occurs in several kingdoms: Fungi, Monera, Protista, and Plantae.[3]
OK I am not an academic but this is significant information for a horticulturalist. The above information is dated and almost laughable in the light of current knowledge but the meat of this is. Some plants can be controlled during germination growth and flowering by altering the day length. This transends the academic because whole industries survive due to manipulation of the phytochrome machanism in plants. There would be no poinsettias for Christmas sales without night shades on the benches to reduce the day length. Chrysanthemum's are timed for market with night shades also. This has been known for some time but I think I was one of the first to experiment with altering both day length, and spectrum while doing my first tissue culture experiments. We used many types of lighting metal halide, sodium vapor, florescent, and incandescent in various mixes. We had access to some experimental bulbs from GE who also provided us with some spectral analysis and metering devices. We found that significant changes in some plants with increase or decreased 810-820 nano meter light sources. This is now better understood and manipulation of both frequency and day length is understood for many plants. There has been significant research on this more recently as to the effect of city lights on vegetation and trees especially with sodium vapor bulbs with high far red output..
Note: In 1976 I planted over 100 Platinus Acerifolia's (200lb root ball) for the city of Albany as they are supposedly light pollution resistant.
At the time I discovered this I was increasingly involved with growing a commercial gesneriad crop and all the spectra experiments on them provided little change. For example of the fourteen different florescent tubes we tried the "Cool White" (the cheapest) was as good as any. Now, many years later, I realize my experiments were unsuccessful with the gesneriads because they tolerate conditions that would kill other species. Such species as chrysanthemums would have shown more profound effect. Many short day blooming plants can be brought into bloom under lights with 11 hr day length. I have found that the gesneriads bloom on either long or short day but grow best on 14 hrs.