Re: breeding 6 fall irises

I was thinking F2 is F1 X F1 sib
Back crossing F1 to parent would be fine if you were trying to reestablish one recessive, but it wouldn't get you to goal of two recessives.
By picking a flat or a plicata seedling from F2, from F1 sibling crosses you would have one parent with one recessive trait fixed. In a F2 of this type 1/4 of the plants would have only one gene or no genes of the second recessive. 26 out of 36 plants would have the second recessive with 2 or 3 of the second recessive. F1 is known to have two sets of genes of each recessive so you are getting 1/6 of seedlings with the F2 fixed recessive and 1/36 to 1/12 with the second recessive. Improving odds of getting the double recessive seedling you are looking for.
As 1/4 of F2 have one or none of the second recessive gene, it is necessary to select several seedlings for a backcross to F1.
Of course you could cross two F2 seedlings to each other, but you would need to select about 6 cultivars and cross each with each other for a total of 26 crosses versus 6 crosses of F2 X F1 . This is necessary because of the 1/4 of F2 having only one or none of second recessive. You need to play statistics so odds are in your favour. 

Chuck Chapman

Date: Fri, 29 May 2009 11:20:50 -0700 (PDT)
From: greenthumbs <greenthumbs777@yahoo.com>
Subject: Re: [iris] Re: breeding 6 fall irises
I know exactly what you're talking about. F2 x F1 in my birds has produced amazing results. I can see the striking similarities with irises and going back to the flat pod parent just as I have gone back to the maternal fowl line 
with the F2s.

  So it would be something like this...

Six Pack x Batik = F1
Six Pack x F1 = F2

F2 x F1
... With each filial cross involving multiple
crosses between its members.

Thanks!


David
















- --- On Fri,
5/29/09, irischapman@aim.com <irischapman@aim.com> wrote:


From:

irischapman@aim.com <irischapman@aim.com>

Subject: [iris] Re: breeding 6

fall irises

To: iris@hort.net
Date: Friday, May 29, 2009, 1:52 PM


<<<<Date: Thu, 28 May

2009 11:35:00 -0700 (PDT)
From: greenthumbs

<greenthumbs777@yahoo.com>

Subject: Re: [iris] Re: breeding 6 fall irises

   > Following usuall odds of BC, you
would need about 3-4000 seedlings to

get

a chance of getting one BC, again depending on particular
alleles of

plicata

not being relevant. Many more if it is relevant.>

Thanks,

Chuck! I was

guessing it would be into the thousands, as per an earlier


remark I made about

only getting 3 seedlings so far and likely needing 100s

or

even 1,000s, I just
wasn't sure how many 1,000s. I have plenty of

space; 21

acres. I'm just not
looking to do that much weeding! LOL


David>.>>




Best bet would be to do as many F1 seeds as possible.


Select best of seedlings   for F2 cross.

Again as many seeds as you can

handle. Select from F2 for

flat and for plicata or if lucky BC.   select


several seedlings from these reselect and cross back to a

selected F1 or

several F1 plants. Odds are you will have a

flat with two or plicata genes

and a plicata with two or

more flat genes  (as long as you select about 6


or more of F2 to try.)


F2 X F1  should give you something to work with.

Chuck Chapman



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