Re: roll of the dice revisited
- To: Iris Talk List
- Subject: Re: roll of the dice revisited
- From: C* S*
- Date: Tue, 12 Jan 1999 09:56:41 -0800
From: Chad Schroter <Chad.Schroter@quantum.com>
Betty queried statistically:
>Cross:
>Iris 1 (strong rebloom) x Iris 2 (warm climate rebloom & strong beard
color,
>with tailored form)
>X
>Iris 1 (same) x Iris 3 (a few warm climate rebloomers in heritage, has
thrown
>blue bearded seedlings & has very modern form)
From statistics if the odds are 1/1000 for the desired result, and you have
dependencies for the final result, then the final odds are the multiple of
all the individual percentages. So 1/1000(F1) * 1/1000(F1) = 1/1000000(F2).
This would hold for a purely random process.
In reality things are not so bad. The breeder improves the odds by
introducing Selection to the process, in effect removing most of the bad
seedlings by not making those crosses in the first place. Only the best
seedlings from the F1 generation will be used as parents, however what is
best may be hard to determine since all the traits desired may not be
expressed if they are recessive. So even if your F1 seedlings do not show a
blue beard or rebloom they may be carriers of 1 or both ; and these traits
could show up in the F2 generation.
From my own experience (limited) and following this list I would place the
odds of a SIGNIFICANT improvement in a TB iris at 1/10000. For a seedling to
be as good or slightly better than BOTH parents may be as low as 1/1000,
particularly for crosses among similar parents.
Chad Schroter
Los Gatos California Zone 9 except lately Zone 8
Email: Chad.Schroter@quantum.com <C*@quantum.com>
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