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Plant Hormones

How does one make a plant hormone?  Don't pay her!  A little plant bio
humor, but really folks, auxin, or indole-3-acetic acid (IAA), is a
naturally occuring plant hormone that promotes adventitous root
formation and root elongation, but only in extremely low concentrations.
An exogenous supply of auxin actually stimulates many kinds of plant
cells to produce another hormone called ethylene, which inhibits root
growth.  Synthetic auxins, NAA are more effective in root initiation and
are used in the nursery industry for cuttings.  Another effect of auxin
is to prevent or slow down lateral bud development, a function called
apical dominance.  Everyone knows that when you prune the apex of a
plant you get more branching.  The growing tip, or meristem, produces
auxin and transports it through the stem.

Zeatin is part of a larger group of compounds called cytokinins that
promote cytokinesis, or cell division, and the production of larger
cells, cell expansion.  Cytokinins have also been shown to delay leaf
senescence, the yellowing and dropping of mature leaves.  The cut flower
business uses this plant hormone to extend the life of cut flowers!
Cytokinins also promote lateral bud development, or branching.

There are many other plant hormones known, such as ethylene, produced by
ripening apples and gibberellin, which promotes stem elongation, and
seed germination.

How these hormones from Azoo work on aquatic vascular plants is unknown
to me, but I would probably give the zeatin a try to see if I can get
lusher growth.  Thanks for bringing up the subject of plant hormones,
they and amino acids for protein synthesis often get little review in
our discussions of plant nutrients.

Gilbert E. Martinez

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