Re: HYB: cold stratification

From what I've read, I get the impression that some genetic mixes
require cold stratification, some require multiple years of cold
stratification, some don't require any.  The initial soak is to make
sure inhibitors present in the seed coat are removed (as was documented
in a recent bulletin article) and to make sure they don't dry out in the
fridge.

I haven't read anything that says they <require> being <frozen>, just
chilled below 40oF.

At one of our Region 7 winter potlucks or a regional meeting, I shared a
table with Mohr?.  He told me about experiments he and his father (also
a hybridizer and Univ Prof in ?Kentucky?) did back in the 60s? or 70s?
concerning cold stratification and germination.

They found they could simulate several winter cycles by chilling seeds
for a month, moving them to warmer temperatures to allow germination,
chilling for another month, etc in order to maximize germination  <and>
speed up time from seed to bloom.  That's where I got the idea for all
this shuffling around of pots and seeds I'm doing.

Their work was probably published in the AIS Bulletin.  I doubt it was
the source of the idea that cold stratification is necessary for
germination, but may give some documentation of it.

In my own experiments, I didn't get much germination after just one
month of continuous chilling, and not a whole lot after two months, but
it went up quite a bit after 2 1/2 to 3 months.  The Spoons recommend 3
months.  After the initial chilling of more than 2 months, more seeds
seem to readily germinate  with less chilling in subsequent cycles.  (no
data, just my impression)

But those are with most of the genetic lines I'm using - who knows what
other lines might do.  .....and then there is that cross that had a seed
germinate in an outdoor pot here in July.

Now that I have a 'wine cooler' with a glass door where I can see what's
going on, I may do another experiment to see if I can get soaked seeds
to germinate without chilling by keeping temperatures below 60oF.

--
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.korrnet.org/etis>
American Iris Society web site <http://www.irises.org>
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