Date: Sun, 29 Oct 2000 16:05:39 -0500 From: psher001@odu.edu To: cp@opus.hpl.hp.com Message-Id: <aabcdefg3151$foo@default> Subject: Re: pitcher plant stratification and germination
Hi Folks:
There have been some interesting comments here on Sarracenia germination.
Ross' comments below (#1) are very interesting. So far we have found that
freezing by itself does nor break dormancy in Sarracenia seed. Last year we
had several of our cooperating schools perform investigate freezing and
moisture as treatments to break dormanmcy in S. flava. Neither treatment
alone, or in combination, resulted in greater germination than controls. In
fact in one school experiment the tried and true method of cool
temperatures (4C) combined with moist soil was the only method that
successfully broke dormancy.
How long was Ross' seed in the capsule outside? Did it pre-stratify prior
to harvest (hence the breaking of dormancy was not due to the freezing
treatment)?
Giberellic acid (GA) breaking dormancy in Sarracenia seed makes sense and
we will have our elementary students duplicate this experiment. We worked
with a girls school last year and they looked at GA to break dormancy in
Sarracenia seed. Unfortunately they obtained the sticky paste instead of a
water soluble powder for the experiment. I was therefore not satisfied that
the failure of this GA to break dormancy wasn't attributable to the method
of GA application.
In item 2 below it sounds like your cold house IS providing the necessary
stratification temperatures (since you mention very chilly outside
temperatures). I don't see how this observation supports the conclusion
that no stratification is needed. Could you provide a little more detail of
when the seeds were harvested, when sown, temperatures, and time to
germination?
Please see our PROPAGATION section at www.pitcherplant.org for new
techniques on sowing and germinating Sarracenia seeds. There is no need to
use the refrigerator to break dormancy in Sarracenia seed if you follow
this technique. If you sow in mid-winter as suggested, or allow enough time
for the seeds to properly chill (ca. 4 weeks at average of 45F) you will
get excellent germination and survivorship. Our overall average germination
on thousands of seeds sown from different crosses is 48%. Please note that
with this technique in one fell swoop you sow, stratify, germinate and
raise the seeds in the same pot. Tented pots with seed are placed outside
in mid-winter and the moist soil is kept constantly damp by being placed in
trenches, tubs, or whatever that maintains the water at 1/3 pot height.
This is a great increase in efficiency for Sarracenia growers. The tent
prevents rain from knocking the seeds about in winter (preventing loss) and
also protects the delicate seedling during germination.
Finally, we sorely need more rigorous, published work on germination
techniques and Sarracenia seed ecology. We have a numbwer of projects
undwerway that should address many of these issues but keep the comments
coming.
Sincerely,
Phil Sheridan
Director
Meadowview Biological
Research Station
Topic No. 1
Date: Thu, 26 Oct 2000 14:07:03 +1000
From: "Ross Rowe" <Ross.Rowe@ea.gov.au>
To: <cp@opus.labs.agilent.com>
Subject: Cold treating Sarracenia seed
Message-ID: <s9f83a93.043@parkes07.ea.gov.au>
My experience has been:
1. Stratification for 6 weeks in the fridge is a waste of time and
space compared to 36 hours in the freezer. Put the seed in paper
packets, immerse in a container of water and freeze, defrost,
allow
packet to dry out for easy separation of the seed and sow.
Germination is excellent, fuss is minimal. Works the same for
Darlingtonia. Obtained similar results soaking the seed overnight
in
10% solution of gibberelic acid instead of stratifying/freezing.
2. fresh seed germinates well without stratification (a few
stragglers
appear the following spring). The context is an unheated
glasshouse that
does not freeze - external temps of minimum c. -6 degrees C, max
day
temps 10-15 during winter. The seedlings are well ahead of
waiting for
germination the following spring.
Ross
Canberra, Australia
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