New Theory on Plant Hormones

Lorine S Horvath lhorvath at plains.NoDak.edu
Mon Jun 30 21:51:04 EST 1997


    Interesting!  Perhaps you can help me explain (and perhaps make some
suggestions as to how to test the explination) an observation on root bud
growth in leafy spurge (Euphorbia esula).  Under normal growing
conditions, the root buds (which appear to be fully formed axilary buds
compleat with leaf primordia) remain dormant.  However, when the root is
separated from the arial plant parts, they grow.  Also, if the plant is
stripped of both leaves and all other axillary buds (from the stem and
crown), the root buds also grow.  However, if one strips only the buds, or
only the leaves, the root buds remain dormant.  If one removes all of the
buds and all but 5-7 leaves, the root buds are induced to grow, but they
grow very slowly, and look like they are experiencing too much ABA (or too
little GA).  Finnally, if the plants are placed in the dark, and they have
their stem and crown buds removed, but all of the leaves are left intact.
the root buds grow. Darkness has no effect on bud dormancy if the leaves
are removed, but the stem and crown buds remain intact ( the stem buds
elongate, and the root buds remain dormant with or without light).  The
last kicker is that if both leaves and crown and stem buds are left intact
in the dark, the root buds initiate growth but not as often (fewer growing
buds) and are somewhat smaller, but do not appear to be stunted (ie they
look like normal not like they are experiencing too much ABA).  What do
you think is happening here?

Dave Horvath
USDA/ARS/BRL
Fargo ND



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