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Warrington, Pat (PWARRING@EPDIV1.env.gov.bc.ca)
Tue, 06 Dec 1994 12:00:00 -0800 (PST)
RE seed germination. Many seeds from cold-temperate or boreal climates will
have a requirement for storage for a certain minimum number of days below
some defined temperature before they will germinate. This makes sense since
it stops them from germinating and dying before any cold period occurs, or
after only a few days followed by a warm spell, when there is still a long
period of winter ahead. Some seeds will also, or instead, require some means
of scarifying their seed coats or breaking them down enough to permit water
to enter. These processes normally take time which prevents germination too
soon or need some special conditions which result in the sseds being in a
favourable situation for survival after germination. Examples are: 1-the need
for acidic or alkaline treatments which necessitate passage through an
animals gut which also leaves the seeds surrounded by fertilizer when they
germinate; 2-the need for extensive abrasion of the seed coat by sand in the
river or along the sea shore which ensures transport for a long distance from
the parent plant and a wider distribution. Many seeds are normally eaten by
birds and require the abrasion of the seed coat in the crop and then benefit
by the deposition in a pile of fertilizer in an appropriate habitat. One
artificial way to mimick this is to stir seeds with an inert abrasive in weak
HCl acid solution to break down the seed coat, in the lab a mag stirrer is
often used for this purpose. Otherwise intractable seeds can be successfully
propagated this way. The best approach is to determine what normally happens
to the seed in nature and try to reproduce the functional aspects of this
natural treatment. Freeze/thaw cycles are probably simply cracking the seed
coat and letting water in, abrasion would likely have the same
effect.