Article 23820 of rec.gardens:
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From: bobw@csg.uwaterloo.ca (Bob Wildfong)
Subject: Re: Selective Seed Saving?
Message-ID: <CFBG0B.28s@watserv2.uwaterloo.ca>
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Organization: Computer Systems Group, University of Waterloo
References: <1993Oct22.175453.3688@infonode.ingr.com>
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Date: Fri, 22 Oct 1993 20:38:34 GMT
Lines: 47

In article <1993Oct22.175453.3688@infonode.ingr.com>,
 <debradfo@ingr.com> wrote:
>If I am saving seeds from an heirloom tomato and
>I have big tomatoes and little tomatoes, does it
>matter which fruits off of this particular plant
>I choose for my seed saving?
>
>I can understand that I should choose from the best
>tomato _plant_ I have, but from that particular plant
>it seems to me that all seeds, regardless of the fruit
>they come from, will have the same genes.
>
>Many thanks.
>
>Dave Bradford	debradfo@ingr.com

Different sized fruit can be caused by genetic differences.  Some varieties,
especially heirlooms, have a diverse _population_ of genes.  This means that
there can be quite a bit of variation from one plant to the next, but they all
represent the same variety.  Modern varieties tend to be bred for uniformity, 
so this has become an unusual concept.

Variations can also be caused by environmental differences.  Two tomatoes on
the same plant can turn out quite differently because they were exposed to
different conditions during their development.  For example, if they initially
formed a few days apart, they may have experienced different temperatures at
this critical stage and might grow up differently.  This is why genetically-
identical twins are almost never _exactly_ alike.

In general, if cross-pollination has been avoided, all of the seeds from a
single plant should contain the same genes.  If there are different-sized
fruit on that plant, it's due to environmental conditions.  The seeds are
created equal.

BTW
If you want to preserve an heirloom variety and find that the plants are not
all exactly alike, that's probably normal.  You should collect seeds from all
of the healthy plants to preserve the variation.  To lose the normal diversity
of genes within such a variety is like losing the variety; you won't have 
preserved it entirely.  Populations without slight variations only exist in
very artificial situations.

 
Bob Wildfong                                       bobw@csg.uwaterloo.ca
Waterloo, Ontario                                  bobw@csg.waterloo.edu
AgCan zone 5b, USDA zone 4



