Re: HYB: kashmiriana, ploidy and more

In a message dated 1/3/02 7:28:25 AM Mountain Standard Time, 
jcwalters@bridgernet.com writes:


> My understanding of this "rule" is that it applies to the number of
> seedlings that must be raised from a particular cross (or type of cross) to
> obtain the desired result in a single plant, not to the number of such
> crosses that must be made.

I have run across many "rules" regarding the number of seedlings that are 
likely to be required to attain a specific goal through planned crosses, but 
those vary from program to program.  TBs or ABs, dominant or recessive 
traits, etc.  This one is quite different, because it refers to the frequency 
of a natural occurrence and all the hybridizer can do is maximize the chances 
of taking advantage of it when it does happen.

I'd love to know the origin of the 1-in-10,000 figure.  Was it based on some 
type of objective analysis or pulled out of thin air as a way of saying that 
unreduced gametes are quite rare?  When I started studying the 
diploid-to-tetraploid conversion and exploring the triploid route myself back 
in the '70s, I got it from a number of sources.  
Of course, it was expressed in slightly different ways so I'm not sure 
whether the variants might have come from the same original source.   

Sharon McAllister


[Non-text portions of this message have been removed]


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