Re: HYB: Muliple Pollinations

From: "Paul Tyerman" <tyerman@hotmail.com>

><
>
>Yes, the tale has made the rounds that you only have to pollinate only one
>stigmatic lip in order to get a full pod. I haven't tested that theory,
>myself.   After dissecting both flowers and developing ovaries, I have my
>doubts -- but that is certainly NOT the same as proof.
>

From my knowledge of botany, multiple style arms link to individual ovaries. 
  In other flowers where there are multiple ovaries there is a carpel 
segment for each ovary and these are directly linked.  From this I would 
assume that each style arm for an iris would have to be linked to its own 
ovary (i.e each style arm would be linked to just one of the 3 segments of 
the seed pod).  This would be a single connection based on the makeup of the 
flower and there would be no crossing over of pollen between the ovaries 
after contact with the stigmatic lip.

I'd heard myself that putting 3 different parents onto the different style 
arms would produce seedlings with characteristics of all 4 parents.  I 
hadn't thought anything of it until reading this conversation.  Now.... 
looking back at my botany training.... it certainly doesn't seem possible 
with the basic botanical structure.

>The old-timers who deliberately made multiple pollinations of rare flowers
>were careful to use a different stigmatic lip for each type of pollen.
>I've tried this myself with wide crosses, using not just different
>cultivars but different types as the pollen parent.  With these
>experiments, I count myself lucky to get even one seed in one chamber and
>have never found seeds in more than one chamber.

I think this is most likely to be a product of the fact you choose wide 
crosses.  As far as I can see there should be no reason why this method 
would be any more unsuccessful than putting one parent onto the three 
stigmatic lips, given that they produce three totally separate sets of 
seeds.

>IF it happened, though,
>I'd expect the different chambers to be associated with different crosses.
>I've never had any problems identifying papa, simply because I choose my
>candidates very carefully.  If the pod parent is a halfbred, and I cross a
>1/4-bred, a 3/4-bred, and a tetraploid aril onto it, the resultant
>seedlings are likely to be quite different.
>

Has anyone out there actually tried this?  My knowledge of genetics in 
irises just plain isn't up to trying this.  So far I've only had a couple of 
different crosses flower and they were basically purple and basically 
orange........ I suppose choosing different parents with a solid background 
in a different colour would give at least some idea of this, but I think 
someone with a bit more expertise needs to try this and come up with 
results.

Anyone out there tried it and can tell us?  I'd be fascinated to find out.

Anyhow, enough of me clogging the airways.  Anyone elses thoughts are 
welcome!!

Cheers.

Paul Tyerman (Australia)..... where Winter has finally taken a bit stronger 
hold.... it has been exceedingly warm here for our winter (and Yes, compared 
to many of you our winter is positively tropical..... but it isn't to us.  
It's been beautifully sunny recently though.   The Iris reticulatas are 
making some progress now and I hope to have some in flower within the next 
fortnight.  Cheers.


>As for "The Birds & The Bees", would you settle for the bees & the
>hybridizer <G>?  The basic biology is that one pollen grain can fertilize
>one ovum.  Not an entire pod.  Not even one chamber.  One egg.  The
>visiting bee or the human hybridizer spreads a generous amount of pollen
>over the stigmatic lip.  The immature ovary contains a number of waiting
>eggs.  The pollen grains burst and pollen tubes start growing down the
>style arm.  Not all of the pollen tubes make it all the way, especially if
>there's more pollen than the stigmatic juices can support.  Some die, but
>the successful ones fertilize a waiting egg.  The fertilized eggs grow into
>seeds, while the unfertilized ones die.
>
>If fully compatible parents are used and the cross is successful, the
>result will be a large number of seeds -- each of which will grow up to be
>a unique individual.  Each has only one "father", but each was produced by
>a different pollen grain produced by that father.  Usually, they even have
>the same father -- but it's certainly possible for a bee to deposit viable
>pollen grains AFTER the hybridizer has been at work.  THAT'S why we
>"protect" our crosses.
>
>Sharon McAllister
>73372.1745@compuserve.com
>
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