Re: HYB: seed germination
iris-photos@yahoogroups.com
  • Subject: Re: HYB: seed germination
  • From: c* s* <c*@yahoo.com>
  • Date: Wed, 2 Nov 2011 09:30:01 -0700 (PDT)
 

I would hazard a guess that the temperature swing is important, but not as much as the length of the daily temperature cycle. As we head into fall and the days shorten, the cooler part of the cycle is longer - even a seed underground can detect this and react the same way plants do to shorter days.

Fall is very warm here in CA, but many trees are losing their leaves anyway.  A line of London Plane trees near my office is dropping leaves now, but the parts of the trees which are right next to the street lights will hold their leaves well into the winter - proving that the 'decision' to drop a leaf is not made by some central reaction inside the tree, or by the ambient temperature, but by each individual leaf and it's detection of the photo period.

Chad Schroter
Los Gatos CA Zone 9

From: Donald Eaves <donald@txol.net>
To: iris-photos@yahoogroups.com
Sent: Tuesday, November 1, 2011 5:58 PM
Subject: [iris-photos] HYB: seed germination

 
The several hundred seedlings that sprouted and normally would have been
lined out remain in the seedling pots. Can't dig here without water. Those
seeds had the best germination of any seeds I've ever planted, percentage
wise. They are also having the best subsequent fall - or late - germination
I've ever had. I'm now looking at hundreds of the little fellows that may
spend their entire life stuck in a pot. I'm convinced now that germination
isn't entirely tied to temps. Germination came to a complete halt in April
when the temps got consistantly warm, but the fall germination started at
the end of
Augst when the temps were consistantly warmer than when they shut off. I
think the seeds must track the trend of the ongoing temps, which is not
quite the same as being dependent on the actual temp. That means they shut
down when the temps are continually rising, but reactivate when those temps
start going lower. Otherwise they wouldn't be starting so early. In any
case, a month or so ago when I counted there were nearly 70 new plants, so
I'm probably close or past a hundred or so now. They keep coming. The
photo is of a cross where there was only one seedling at the end of spring
and now has twelve in the fall, the newest showing up today. Seen a lot of
that this fall in the pots. Seven pods that had no germination at all now
have seedlings. I really wish now I hadn't dragged out any of the stored
seeds and planted them. I'm not at all sure even with some rain and
moisture I'll be able to manage the number of seedlings I have.

Donald Eaves
d*@txol.net
Texas drought zone, USA


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