I grow mostly by sunlight on my balcony. I've also got some white LM301B lights, which seem very popular among those growing by artificial light only. Greenhouse growers supplementing sunlight still seem to prefer red-blue. You could tell a story like "some intermediate wavelengths will improve yield, and you can get them either from white LEDs or from the sun", though I'm not sure how rigorous the evidence is for that.
I don't think there's much about plant hormone use that's specific to hydroponics. People use rooting hormone and foliar sprays of plant growth regulators and such, but they do that in soil too.
I don't think there's much about plant hormone use that's specific to hydroponics. People use rooting hormone and foliar sprays of plant growth regulators and such, but they do that in soil too.