Experience Using GEM Germplasm in a Public Breeding Program Jim Hawk, Tecle Weldekidan, and Travis Frey Department of Plant and Soil Sciences

GEM Objectives To improve and broaden the germplasm base Traits targeted are agronomic productivity, disease and insect resistance, and value-added The ultimate target is to release lines for applied and basic research

Topics for Discussion 1.Choice of parental germplasm 2.Breeding methods/strategies 3.Hybrid evaluation 4.Opportunities/challenges 5.Summary

Choice of Parental Germplasm

Breeding crosses- accession x elite inbred line Elite inbred lines- all lines not more than one breeding cycle removed from a commercial product Over 550 breeding crosses – which ones should receive priority for pre- breeding? Other accessions ?

Breeding Cross Evaluations Locations: USDA – GEM, Ames – Mike Blanco Golden Harvest, IL – Kevin Montgomery University of Delaware, Newark, DE No. of Breeding Crosses Evaluated: 2003 – – 173

Traits Evaluated in Breeding Crosses Adaptability Days to flowering Ear and plant height Ear traits Disease and insect resistance Root and stalk lodging Stay green Plant appearance

Recommended GEM Breeding Populations Evaluated at Three Locations, 2003

Breeding Crosses Utilized at the University of Delaware ~10/year Most 75% corn belt, some 50% Grow ~1200 plants/population Self plants/population

Breeding Methodology Pedigree Mass selection for more heritable traits - plant and ear height - maturity - ear traits - disease and insect resistance - root and stalk strength Balance offensive and defensive traits

Number of S 1 Ears Selected from GEM Breeding Crosses

Breeding Methodology Select S 1 ears/breeding cross S 1 families  6-8/family Family and mass selection for more heritable traits Sampling within best S 1 families – 1-3 S 2 ears Goal – 50 S 2 ears minimum from better populations Discard poor breeding crosses

Number of SS S 2 Lines Selected from GEM S 1 Families

Number of Non-SS S 2 Lines Selected from GEM S 1 Families

Hybrid Evaluation ~50 S 2 testcrosses + 3 commercial checks Use testers with good GCA and agronomics (roots, stalks, disease and insect resistance) Locations/reps: 3 DE (1 dryland, 2 irrigated) with 2 reps/location, USDA- GEM Ames-1 rep Second year YT- 2 testers x 8 locations

DK212T:N11a10 Lines Crossed to Pioneer SS Tester

CUBA164 Lines Crossed to LH185

Opportunities/Challenges Trait improvement using selected GEM lines - Grain quality, disease, insect resistance, etc. Use additional testers

Opportunities/Challenges Sister line mapping studies – DKXL212:N11a (DE4) DKXL212:N11a Recycling - Further improvements needed for commercialization

DE4 Recycled Lines Crossed to LH244

Summary Focus on adaptability, agronomics, disease/insect resistance first - Breeding cross evaluations - Family and mass selection for more heritable traits May be useful to re-evaluate better breeding crosses in additional years

Summary Germplasm for new breeding crosses - Lines, improved populations etc. Useful genetic variation within adapted GEM families

Summary Practice art of plant breeding Better to discard earlier than later Focus on better germplasm Plant breeders: Short-term pessimists and Long-term optimists

Acknowledgements Wilfredo Salhuana USDA-GEM, Ames Holden’s Foundation Seeds Mycogen Seeds Pioneer Hi-Bred Int.