Patience, Pride, and
Prejudice
Some Experience with Maize
Germplasm
Tom Hoegemeyer
Prejudice
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Exotic Maize is too tall, late and not useful
in my program
Exotic Maize is hard to work
I’ve tested Exotic Maize in hybrids, and the
crosses yield less than what I have now
The native North American races are best
suited to the conditions I breed for.
Prejudice
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Usual technique for exotics: Inbreed
directly in the population, select the
earliest plants, cross the few that work
easiest to one tester, throw all of them
away because they yield less than checks.
Pride
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While there are lots of races and
populations of maize, God put the best
ones here in the US.
My program (or company, or country, etc.)
has sorted through the available
germplasm, and we are working what
gives us the best chance to find new,
better hybrids.
Pride
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In the US we have done, and are doing
the best quality and largest quantity of
breeding with maize, and consequently,
the best chance of success is working with
this domestic material.
In working exotic germplasm, I would
rather start with the GEM sources, and
select what I want. (If it wasn’t invented
here…..)
Pride
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We have all the performance we need.
We are more interested in adding biotech
traits to the great hybrids we already have.
MAS will be more efficient in germplasm
that is already adapted.
We’ll identify what we need via genomics,
and add it selectively via MAS.
Experience
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Most of your observations are correct:
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Generally will yield less than current hybrids
Adaptation problems
Taller, later, poorer roots
Significant advantages in health, grain quality
Will result in fewer hybrids in next five years
on a per shootbag basis
Need to be committed to pollinating well into
August
Experience
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USGEM testcrosses do have yield
To test for yield, generally better to test
under low stress, warmer—May not April
planting, don’t only look at earliest items
within a population.
Look at yield on a relative basis, not an
absolute basis. Keep the best ones!
Experience
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In last five years of testing USGEM
experiments in Nebraska:
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Every year, there have been a few entries
within an LSD of the best checks.
The lines/populations from the “northern-ISU”
GEM are only slightly better adapted than the
“southern-NC State”.
Odds are much better of finding high yields in
selected S2’s than in populations per se.
Examples
CHIS775:N1912-389-1/LH200
Pioneer 33P66
203 14.9
210 17.5
FS8B:S0316-1118-1/LH283
Pioneer 34B23
179 15.0
195 14.7
Best ones still have some adaptation issues
which impact yield
Examples
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DK844:S1601-997-1-1/TR7322 199 18.9
DK844:S1601-926-1-1/TR7322 185 19.0
DK888:S11-1943-2-1/TR7322 193 20.9
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Hoegemeyer 2679
Pioneer 33P66
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With the right testers, some WILL yield
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186 20.7
190 21.0
Patience
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In exotics, especially in populations, you
need to practice ART of plant breeding.
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Large samples
Watch for plants that do obvious things well
Select plants to self, rather than selfing a
sample, like the earliest 20%
Think about how materials might be used as
part of future projects
Other Exotic Material
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(NC368xHX853)F4’s/TR7322
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14 of 89 were statistically equal in yield to
Pioneer 33B50, 8 were as dry or drier.
(NC368xHX853<2)/TR7322
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4 of 62 were statistically equal in yield to
Pioneer 33B50, all 4 were as dry or drier.
Patience: Re-cycle
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Most (all?) material, whether exotic inbred
or GEM selection won’t be half a hybrid!
Cross best exotics with high performing
inbreds, use large samples!
Visually select for high heritability traits.
Use testers with excellent roots/stalks.
Patience
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Take advantage of work and contributions
of others
Inbreds developed from exotics may be
more immediately useful than pop’ns.
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Iowa State, NC State exotic derived inbreds
will have better adaptation responses
Elite inbreds from exotic hybrid programs
more likely have traits needed for inbreeding
here
Patience
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In longer term, we need to accumulate useful
variation from the exotic maize populations.
GEM is an excellent vehicle.
Think about where to go from here in next 30
years. New heterotic paterns? New breeding
pop’ns built from GEM lines? Use genomics and
MAS to custom build new inbreds from exotics?
How do we best keep all the “parts”?
Thanks for your patience.
The End