jackrowe at compuserve.com
Sat Nov 1 13:51:50 EST 1997
I can believe that to-us subtle changes in light frequencies can have an
effect on seed germination... what appear to be small initial influences
can often result in profound changes in outcome. This mechanism might
prevent weed seeds (which are often impressively-long-lived) from
germinating before the canopy is opened above them or they are carried on a
hog snout out into the open and replanted.
A lot of weed seeds have two dormancy requirements. The first is a ripening
or maturation stage, which they spend underground or out of the light. The
second requirement can then be satisfied by exposure to light. This is true
of a lot of amaranthus', for instance, and Chenopdiums. This is the reason
for the common name "pigweed", historically applied to both these genera...
these plants are often germinated by rooting pigs, who expose mature seeds
to light in the course of their rooting and so cause their germination.
These are called weeds of disturbed soil and they tend to be fast-growing,
tolerant of poor soil, and fast to produce huge quantities of tiny seeds.
In the case of the two I mentioned, good eatin', too.
This makes a good argument for constant-mulched, no-till gardening, as does
the erosion cited by Dan, as does simple ergonomic sanity. Rodale Inst., by
the way, has found a great decline in the germination of weed seed
resulting from soil disturbance, if weeding and/or digging is done at
night, and soil thus disturbed is re-mulched before daylight returns.
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