Plant Hormones

Superglue

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Aug 14, 2008
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Awhile back, in one of my bio labs, my class studied certain plant hormones and the effects they produce when introduced to the plant in certain concentrations. It was pretty amazing to see the changes that these hormones induced in the plants. My question is, does anyone know if many of the popular known aquatic plants respond to plant hormones like gibberellic acid, auxin, and cytokinins?
 

Tom Barr

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Jan 23, 2005
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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
 

Superglue

Junior Poster
Aug 14, 2008
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Thanks for the info Tom. Yeah, in the lab we applied the hormones directly on the apical meristems of terrestrial plants, not aquatic plants. I was thinking I could have just dosed a certain amount for aquatic plants to try it out, but I didn't factor in the bacteria eating the hormones, hormone degradation, etc. I wanted to see if there was a way to make my plants grow faster when coupled with all the normal stuff (Co2, lights, ferts, etc). Oh well.