Auxin Induced adventitious root formation

Ross Koning Koning at ECSUC.CTSTATEU.EDU
Mon Nov 20 12:36:48 EST 1995


At 12:42 PM 11/17/95 -0800, Ethan Strauss wrote:
>Hello,
>We have just completed an experiment in an intro biology class trying
>to induce adventitious root formation in bean plants. The data seem to
>show quite nicely that IAA inhibits adventitous rooting.  Going back
>and rechecking my books I seems that this is not supposed to be so.

Ethan,

I'm not sure what your conditions are, but you are right
that auxins should stimulate rooting *at the right concentration*.

I have a course for non-majors where we sprout mung beans for
about 10 days in the greenhouse (could use lights too).  Then
we sever the shoots at a point 2 cm below the cotyledonary node.
The seedlings are stood in clear plastic cups, 10 per cup, with
20 mL of auxin solutions (I use 10-3 M, 10-5 M, 10-7 M, and 0 M
Indole Butyric Acid).  The seedlings in cups are placed a few
inches below a shop-lite (fluorescent fixture) with continuous
illumination.  The level of liquid in each cup is maintained at
the cotyledonary node by adding distilled water as needed.  After
one to two weeks, the root primordia have grown out a few mm.
The 10-3 M IBA is herbicidal (all of them die very obviously and
after severe epinastic responses).  The 10-5 M IBA usually induces
excellent rooting (40-50 roots per shoot).  Shoots in 10-7 and
0 M IBA generally have 5 roots or so and they are found only at
the cut surface.  The concentrations were chosen to show "too much
of a good thing," some "effective" dose, an "insufficient" dose,
and a no-dose control.  This works very well for me providing I
keep a close eye on the watering, and the light at a sufficient
level.  Student T-testing works out nicely for comparing any two
of the concentrations (experiment vs control).

ross

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 \ Ross Koning                                  \
  \ Biology Department                           \
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