Re: HYB: Long Question about Rebloom

Like you, Tom, I was pleasantly surprised to see rebloom in some
seedlings where I didn't expect it.  I asked some questions about it
here and will share what I got from the discussions, plus what I think
I've read in the Bulletin, Tall Talk, & the RIS.  Hopefully to be
corrected by those who know a <lot> more about the subject.  I think the
discussion here was two years ago.

Various types of rebloom are thought to be  'failures' in some part(s)
of the physiology of the plant that would normally tell it not to bloom
any time other than spring.  It's not know for sure whether or not those
'failures' are in one trait or several combinations of traits (enzymes &
all that complicated stuff that genes do with hormones in response to
changing light levels with changing seasons etc), but some folks think
that there are not only several different types of those genetic
failures around in modern irises, but that it's an 'easy' failure (i.e.,
can arise spontaneously as a 'new' failure, hence rebloom in seedlings
from non-reblooming parents).

If you have the same <type> of genetic 'mistake' that causes rebloom in
<both> sides of the pedigree, the likelihood of getting rebloom
seedlings is higher than if you have two different types of mistake.

So, like a recessive trait, the probability of getting rebloom <is>
higher when both parents are rebloomers or have rebloom ancestors,
depending on how well the mistakes match up.  I have no idea if there
are "dosage" effects that go along with the different types of rebloom
'mistakes' (i.e., if you will never get rebloom unless you have 4 sets
of mistake A, but can get rebloom with 2 doses of mistake B combined
with 2 doses of mistake C).

Then throw in on top of that all the peculiarities of how various
individual cultivars respond to temperature, humidity (?), moisture
supply, and nutrient availability, and it can make it really hard to
predict whether or not a particular seedling will rebloom.

Was that helpful?  Somehow, I bet it isn't ......

And of course, what I said applies to TBs with 4 sets of chromosomes,
not the two you are working with in diploids.  Your work with diploids
might sort some of this stuff out as to how many doses of mistakes it
takes to get 'repeat' bloom vs everbloom vs spring/fall bloom.
--
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>
talk archives: <http://www.hort.net/lists/iris-talk/>
photos archives: <http://www.hort.net/lists/iris-photos/>
online R&I <http://www.irisregister.com>

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