Re:HYB: backcrosses, etc..

Anecdotal examples....
I was able to get seeds pretty easily from pallida (diploid) crossed
with various tetraploid TBs.  I used a lot of pollen, put it on several
times/day and didn't expect a high rate of takes.  I got as many takes,
always full seed pods, from those pallida crosses as I do between modern
tets (poor rate of success for everything here).  My bigger problem was
having any pallida bloom - usually frozen out.

Seed germination was also pretty high.  I don't know the chromosome
count of the F1s.  One of the crosses has produced several 'bee' pods
with viable seeds, none have produced pods from intentional crosses.  At
least one of the bee pod seedlings is pod fertile with tet TBs.

<And on another note, "TWOI" I think, mentions that in crosses of
                       diploid seed parent x tetraploid pollen parent
that 40% of the
                       resulting seeds grow up to be tetraploid, because
irises have what's
                       known as a "triploid block". This block prevents
the formation of
                       many of the possible triploid embryos, which
gives you a better than
                       expected ratio of tetraploids to triploids.
Theoretically there would
                       have been very few (relatively speaking)
tetraploids from such a
                       cross. On the down-side I don't think there are
usually many (if any)
                       seeds that form at all from this type of cross.
You have to be really   persistent.                       Tom>

--
Linda Mann east Tennessee USA zone 7/8

Tennessee Whooping Crane Walkathon:
<http://www.whoopingcranesovertn.org>
American Iris Society web site <http://www.irises.org>
iris-talk/Mallorn archives: <http://www.hort.net/lists/iris-talk/>
iris-photos/Mallorn archives: <http://www.hort.net/lists/iris-photos/>




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