Hormone Absorption

John E. Silvius SILVIUSJ at CEDARNET.CEDARVILLE.EDU
Sat Nov 20 12:06:53 EST 1999


REGARDING UPTAKE AND TRANSPORT OF Gibberellic Acid:

John E. Silvius
Professor of Biology
Box 601
Cedarville College
Cedarville, Ohio   45314
E-mail:   silviusj at cedarville.edu 
http://www.cedarville.edu/dept/sm/jes_www.htm

>>> "David W. Kramer" <kramer.8 at osu.edu> 11/19/99 01:04PM >>>
 Would we get the same effect if we "watered" the plants with the GA
solution, applying it to the soil?  [I'll try this next quarter but
thought some of
you might have the answer!]

REPLY:   We have no experience with pea, but with dwarf corn, we have
used both foliar (adding down into the whorls) and soil applications
(around the base of the plants where adventitious roots are forming). 
 We have not actually checked whether base-of-plant applications alone
are sufficient, but I have suspected that there must be some uptake
from roots.   [Will have to check this for sure.]

>>> "David W. Kramer":
How do the pea plants actually absorb the GA?  The stems and leaves
have a heavy cuticle so I assume it enters via stomata on the leaves
and stems but what then?  Does it enter cells by active transport?
simple diffusion? some other mechanism?  Is it transported in the
xylem or phloem or by other cells?

REPLY:  Hopkins (Introduction to Plant Physiology, 2nd ed), page 350
suggests that GA may be synthesized in root tips and may be
translocated in the xylem.   Sounds like a good use of a hydroponic
system with pea and corn.  






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