Re: Propagation/Germination
- Subject: Re: Propagation/Germination
- From: T* &* M* R*
- Date: Fri, 20 Jul 2001 08:43:31 +1200
Barry Garcia wrote:
>
> Actually, the seed was found in a dry lake bed that was once a lotus pond,
> cultivated by Chinese buddhists. The seed was actually 1,288 years old!
>
> here's a quote from an article about it:
>
> The researchers cited several reasons for the seeds' longevity, including
> a thick shell that protected the seed from air and water and the presence
> of L-isoaspartyl methyltransferase enzyme, identified in the 1980s by UCLA
> biochemistry Professor Steven Clarke as the first protein-repair enzyme....
Thank you Barry
My mental computer is not as sharp on details of this kind as it once
was, but in any case I don't think I ever saw that interesting full
report of the find which you quote.
I wonder if other "hard" seed's coats contain the same or similar
enzymes. I think if they do they must usually break down much sooner in
most cases, as the span of hard seed dormancy in clover would be more in
the range of 5-25 years if I remember correctly rather than a thousand
or more, and in that case anyway a few seeds naturally break dormancy at
regular intervals.
One of the other mechanisms nature uses to save seed from germinating in
unsuitable conditions is the need most have for light stimulation to
break dormancy. Only the merest flash of light is necessary to trigger
the process for many, so even surface hoeing can be enough to stir weeds
into action. In any case for many kinds thay do not really need to be
brought right to the top, the light penetrating down to about one inch
below the surface being apparently often enough to do the job. The fact
that they will not germinate if much more than an inch below the surface
is obvously a safety mechanism to prevent deeply buried ones expending
all their energy before they can get a shoot above ground.
There are some plants we grow in our gardens (Impatiens is one) which
will only germinate if the seed is right at the surface in full light.
Interestingly, at least the majority of these light-sensitive seeds are
very tiny and perhaps their limited food reserves would not be enough to
let them struggle up through even an inch of soil before they can unfurl
their leaves and make some more energy food.
Rothamstead Agricultural Experimental Station in England had (?has) an
experiment running to test the longevity of buried seeds of various
weeds and when I last heard details had already found that some species
could easily lie dormant a hundred years buried in the soil and still
germinate successfully when brought to the surface.
The fact that they leave old buried seeds still buried and bury new ones
with mulch is very a good argument for using no-till methods for weed
control in both agriculture and horticulture (apart from that system's
major advantages in promoting good soil structure). A dollop of new
mulch will often prevent even new seeds which blow into the bed
receiving the light they need to grow and can also smother young
struggling seedlings.
Moira
--
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand, SW Pacific. 12 hours ahead of Greenwich Time
