Re: selfed or not?

pumpkins@mallorn.com wrote:
> 
> Please forgive me but I've more questions regarding genetics and
> terminology. Am I correct in stating that when a flower is pollinated
> with pollen from the same plant it is considered 'selfed', but, if I
> grow two seeds from the same pumpkin and pollinate plant 'A' with pollen
> from plant 'B' it is considered a cross? Which would be the better
> practice?
> 
> Greg
SELFED: any time you place pollen from a plant onto eggs of the same
plant you have selfed the plant. In corn the third season the plants are
very inferior and only about 1/3 or 1/2 produce seed and then only 5 to
20 seeds. I do not know what happens in pumpkin. If you begin with corn
that has been selfed or sibbed in the past then the results may not be
so bad.
SIBBED: if you plant the seeds of one pumpkin (regardless of its origin)
and place pollen from one plant on another plant, we call that sibbing
and a plant geneticist understands immediately what you are doing. The
experience of corn geneticists is that if you sib the best plants you
often get gradual improvement of the traits you selecting for.

GENETIC CONTENT OF A SINGLE FRUIT.  Very likely no two seeds in a fruit
have exactly the same gene content. You need only look at a family of 12
human childern. You can easily tell them apart. Obviously no two
childern have the same genomes (gene content). Probably every seed in an
AG fruit has a different gene content. 

CORN: I have worked with corn since 1947 and have done this sibbing and
selfing many times on open pollenated heirloom strains of corn and
always had the results stated above. I use corn examples because I am
sure I hve my facts straight in corn. 

To SELF or NOT to SELF: If you are lucky, selfing gets you to where you
want to go quicker than sibbing. A corn plant takes up only 5 square
feet and one can afford more gambling type experiments. 

Could one plant AG closer and prune severely to permit more plants per
plot and more selection for sibbing and selfing--I wonder. If so one
could be be more certain of the genes present. In corn, more than one
ear sometimes occurs. I often sib the top ear and self the less
dependable second ear. You can easily try that with AG.
  Lets suppose you are working with 700 pound lines of AG, but due to
severe pruning and close planting you only grow 50 pounders in your
sibbing and selfing plot. You have not damaged your genetics. I admit, I
do not know how you can tell whether you still have a 700 pound line
without planting at wide spacing. However, if you trying to get a line
homozygous for color, mildew resistance, or other important trait, you
may not need a 700 pounder that year. 
  Brad Walters, you offered me some seed and so did Barb(FL), if either
of you has some seeds which you think may be nearly pure for some
important traits (or what ever interests you), I would like to try this
idea of severe pruning and small plants to fix color or other important
trait. Notice this expt requires seeds that we know came from the same
fruit (no FAKE seeds). I would try to grow one or more selfed fruits and
one or more sibbed fruits on each plant. Is that possible on a small
plant? 

-- 
Harold Eddleman Ph.D. Microbiologist.       i*@disknet.com 
Location: Palmyra IN USA; 36 kilometers west of Louisville, Kentucky
http://www.disknet.com/indiana_biolab



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