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Dive into the world of maize germplasm breeding strategies, where patience, pride, and experience collide. Explore the challenges and successes of working with exotic maize varieties, navigating prejudice and pride along the way. Gain insights into the best practices for selecting, testing, and crossbreeding maize germplasm to unlock new, high-yielding hybrids. Discover the importance of patience in plant breeding, leveraging the diversity of exotic materials to enhance breeding programs for the future. Delve into the art of plant breeding, using large samples and selective techniques to uncover the potential of maize germplasm. Embark on a journey towards building new and improved inbreds from exotic lines, utilizing genomics and marker-assisted selection for a successful breeding future. Embrace the balance of tradition and innovation in maize germplasm breeding.
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Patience, Pride, and Prejudice Some Experience with Maize Germplasm Tom Hoegemeyer
Prejudice • 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 • 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 • 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 • 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 • 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 • Most of your observations are correct: • 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 • 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 • In last five years of testing USGEM experiments in Nebraska: • 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 203 14.9 Pioneer 33P66 210 17.5 FS8B:S0316-1118-1/LH283 179 15.0 Pioneer 34B23 195 14.7 Best ones still have some adaptation issues which impact yield
Examples • 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 • Hoegemeyer 2679 186 20.7 • Pioneer 33P66 190 21.0 • With the right testers, some WILL yield
Patience • In exotics, especially in populations, you need to practice ART of plant breeding. • 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 • (NC368xHX853)F4’s/TR7322 • 14 of 89 were statistically equal in yield to Pioneer 33B50, 8 were as dry or drier. • (NC368xHX853<2)/TR7322 • 4 of 62 were statistically equal in yield to Pioneer 33B50, all 4 were as dry or drier.
Patience: Re-cycle • 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 • Take advantage of work and contributions of others • Inbreds developed from exotics may be more immediately useful than pop’ns. • 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 • 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.
