HYB: germination - thoughts from an outsider

I have really been enjoying the posts on germination.  Although I am
relatively new to iris, I have germinated a lot of rose seed.  Roses seed is
also hard to germinate and rates are often low, even among the professional
breeders. However, there are some interesting similarities.   Most of the
professional and hobbyist hybridizers use a "burrito" method of some sort for
rose seed.  It is commonly accepted that there are multiple mechanisms that
inhibit germination in roses: water soluble germination inhibitors, water
impermeable membranes and temperature (chilling) requirements.  It also
commonly accepted that the material of the seed pod (which rose breeders call
hips) contains germination inhibitors and must be separated from the seed as
soon and as completely as possible.  Rose seed are so hard that often a
blender is used to mince the hips and nick the seeds, which are then separated
from the pulp with a sieve under running water.

Since we all agree that there
are multiple germination inhibition systems at work in iris, and that these
are genetically controlled like all other traits, why would we not expect that
different crosses have different levels of the different  inhibitor systems
and different requirements to germinate?  In fact, I believe that we can
select for breeding lines that germinate under the system we use, just as we
select for any other trait. 

As for second year germination, I suspect this
is a system that nature (evolution) has selected for because it has advantages
in the long term survival of a species.  If some of your seeds do not
germinate the first year, you have an advantage if some disaster or
environmental condition wipes out the crop of seedlings that year.  This was
proven in an insect system some years ago.  A pest called corn rootworm
attacks the roots of corn in the immature stages. The adults lay their eggs in
corn fields to hatch the following year.  Farmers would rotate soybeans with
corn to stave the immature rootworms the following year.  After this
successful approach was used for years, some fields that had been in corn,
then soybeans, then corn again developed rootworm problems.  It was found that
the farmers had been selecting for a strain of rootworms that laid eggs that
did not hatch the first year. My point: using seedlings that required two
years to germinate may be
 selecting for iris lines that have seeds that need two years to germinate.
Is that bad? No, but it does mean that it may require more work (burritos
chilled, warmed, chilled and warmed again; and again??)

The great news is
that all this is FUN, or we wouldn't be doing it.  Most of us will never make
any real money breeding iris, but it sure is fun.  We all want to see as many
seedlings from each cross as we can, after all; plant breeding is always a
numbers game.  The more seedlings that bloom, the greater the chance the
flower we have been seeking is there.  So whatever I can learn from these
discussions that will help me do this is just great, thanks to all who take
time to contribute.

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