No, not really.
You can buy plant horomones and dump the cemicals on aquatic plants, I've never seen any results on growth that I could attribute to them on submersed plants.
Some companies add them to their traces, or suggest them for after trimming etc, but if you buy some SuperThrive, common for the last 50 years at most any garden center, Home Depot etc, add those, you see no effect. If you use specific bio grade hormones, the same similar result occurs.
Most hormone responses are temporary, they also are externally applied, plants already have their own internal endogenous hormones they use to control growth signalling.
The only verified response was with flowering in some species of emergent gowth Crypts, see Kane et al for that reference. I also was able to induce the same response(and only 1X after treatment) in the species. Still, not much use for aquatic plants, the hormones are quiclyk washed away and are gobbled up by bacteria. So internal endogneous hormones seem to be the only real influnce.
While you see changes in bio lab, you likely will never see any in an aquarium trying to produce only vegetative growth, but you are welcomed to try with various products such as Super Thrive, Root Hormone etc. You an dip the ends of stems to try and get better rooting after cutting, I never found any difference. I tried to measure root biomass dry weights as well in 8 common aquarium species.
No significant differences vs a control for root hormone.
I think folks get a bit excited by plant hormones, but the reality is that in order to have a certain amount of heighten growth, they still need a source of light and source of carbon(CO2) and nutrients, as well as the time to do so.
So the plant still has to allocate those nutrients in response to the hormones, and if they are lacking, no response will be seen.
So there's a few things going on that the proponents often do not tell you.
For things like fruit production/grapes, control of flowering etc, they work well and are worth while for agriculture/horticulture. But would you spray 30,000$ worth of Gibs on your vinyard before harvest to fatten up the grapes if you knew there was going to be a heavy rain latrer than afternoon?
Probaly not.
Same type of thing here except even worse.
No fruit, no flowers, no reason and the water will wash the chemical away much faster and dilute.
Regards,
Tom Barr