AG Germplasm

pumpkins@mallorn.com wrote:
> 
Eddleman's reply to Brock:
Eddleman has edited Brock's words to shorten the reply
> 
> I have always felt that AG's sibbed (not selfed) seed have at most
> a 5% potential to hit 700+ lbs.  Only one seed, the 567.5 Mombert, 
> has surpassed this and is crowned the king of AG seed for its high 
> rate of 700+ [progeny].   But it seems we [usually] don't see more 
> than 10 to 12 good 700+ pumpkins from [the 300 seeds in] a good 
> background AG. -- [That's] not real impressive.
I have already learned an important lesson from those who have written
me with themes similar to what Brock expounds above. While I have no
plans to grow for records, the genetic questions are very interesting
and I wish I had known in 1954 the genetic lessons this list has taught
me in only a month. While I try to grow some C. pepo every year for
pies, keep in mind that I have not yet grown any AG. 
  I am only guessing but I think we should work on developing (by
sibbing) some great AG germplasm lines. Those AG growers who have the
space and interest can work at improving those lines and, if willing,
made the seed available to others. 
  A competitor could then choose 2 lines and cross them to obtain hybrid
seed for contest plants and progeny test to pick his hybrid for his
contest crop. I realize folks have already been doing this for decades.
I suppose the big problem is that an AG plant takes so much space that
not much culling of runts can take place. How can get more plants to
select from?
  Most of my corn breeding was also breeding for "show" I was trying to
grow beautiful flint ears demonstrating genetic traits which teachers
could use to get kids interested in Mendelian Principles of Genetics. I
wanted the ears to be so beautiful that the kids would remember the
principles. 
  My best success came from developing lines by sibbing and then
crossing for progeny tests. I then grew the winning hybrid in quantity
to sell to schools. I often got two beautiful ears per plant and
sometimes 3.
  
> One problem is there is no fixed number of good seed one could 
> bank on. But I sometimes feel that I should  attempt to do that. 
> That after say 4% of good seed has been found by planting and making 
> it to the scales WE then take  serious notice and go after that 
> particular cross.  I have always felt that going back after the
> 1% remaining good seed wasn't the best way to go. I would appreciate 
> your thoughts on this.
  I may not understand your plan. If you are saying, "Let's try to look
at the methods available to develop some dependable inbred (prob by
sibbing) lines, then I agree. 
  I think you are hoping that it will be possible to develop some lines
which can be crossed to produce big pumpkins every time. I am only
guessing, but I think that is a good plan with lots of examples of
success in other crops. 
  As I have written before, present day strawberries have lost some of
the resistance diseases and insects which are found in some wild plants.
Some breeders are trying to find good wild plants to start the breeding
all over again. Examples are Ag Canada at Simcoe and a station in SW
Washington USA and I was doing it on a smaller scale before I learn
about the larger government efforts.
  As we try to develop elite sibbed lines, we need to discard plants
which show susceptibility to disease. We could inoculate the vines with
disease and use only the survivors. 

> 
> Some laymen like myself feel that the success of the 567.5 may have
> been from some sort of Hybrid vigor.
  That is reasonable. Alternatively, it have also have had a lucky
supply of rare, superior alleles (genes). Keep in mind that at a given
locus, there might be many different alternative alleles (versions of
the gene). It often seems that having two copies of the best gene at the
locus is not as good as having two outstanding different alleles
(hybrid). Actually, sometimes two inferior alleles complement each other
somehow to be the best combination. [Such examples are known; the sickle
cell form of hemoglobin may be one example. It may confer malaria
survival.]

> This seed was white.  [Thanks, I did not know Mombert 567.5 was white 
> seeded]. I have 
> seen two white seed parents create a tan. I have seen two tan seed 
> parents create a white. Sometimes you can get some that look like a 
> combo of both tan and white.  Most growers feel that seed color 
> doesn't tell us much.  But don't know for sure.
  I did not mean to imply that seed color was important. I just thought
it might be an interesting mutant to study. Since the 750 McIntyre 1998
seeds are white and finely wrinkled and others say other white AG seeds
are wrinkled, I wonder whether the mutation is in the seed coat--perhaps
the normal colored seed coat is missing. 
  When two white seeds are crossed and produce 100% TAN seeds it
suggests two gene loci are needed to make TAN. If one gene locus makes
TAN color and another locus makes the outer coat then a defective gene
in either locus causes white seeds and crossing these two homozygous
white seeds might produce 100% fruits containing white seeds. If the F1
is selfed one might expect 9:7 ratio, but result would depend upon
dominance.

> If a good lineage AG seed doesn't cut it the first few 
> attempts we are quick to look elsewhere.  Mainly because you put
> in a great deal of work on a plant and its hard to risk that time
> on a good cross that has let you down.  But if the ratio is as tough as
> it appears to hit a 700+ the 5-10 growers that do plant a certain cross
> and  miss seems like a drop in the bucket.  But this is our practice 
> and very hard to overcome.  Are we destined to only have these kind 
> of odds or how can we improve our bets....brock

  I think the problem is that the plants take so much space that our
slections are from too few individuals. If we could make AG commerial so
we could afford whole fields of them, then we could select from more
plants. I do not have any solutions at this point. 
  The phenomen of some outstanding plants being great as germplasm and
other outstanding plants being duds as gene sources is common in all
crops.
  Selecting the largest ear of corn from a corncrib was somewhat
successful, but selecting from the field from sibbed plants proved much
better. It seems to me that choosing your seeds from the winners at a
weighin is similar to the old low-success practice of picking the
biggest ear of corn from a crib.
--
Harold Eddleman Ph.D. Microbiology and Genetics      
i*@disknet.com 
Location: Palmyra IN USA; 36 kilometers west of Louisville, Kentucky
http://www.disknet.com/indiana_biolab/pk.htm



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