Increasing the Genetic Diversity of US Northern Corn Belt Hybrids with Tropical and Temperate Exotic Germplasms.

Breeding with improved exotic germplasms in maize (Zea mays L.) is a unique way to increase genetic diversity and obtain significant genetic improvement. The Latin American Maize Project (LAMP) evaluated over 12,000 maize accessions comprising 74 % of the known races of maize found in Latin America and US germplasm banks. A long-term continuous effort to incorporate LAMP germplasms in the northern US is represented by the Early Germplasm Enhancement of Maize (EarlyGEM) project led by North Dakota State University (NDSU) maize breeding program since 1999. It uses the GEM program as an intermediate adaptation process. This project identified nine populations to produce BC1:S1 lines out of screened 152 GEM S3 lines. It uses NDSU released line ND2000 as recurrent parent. A MS research study was conducted to understand the genetic variation present among the diverse BC1:S1 lines and their competitive potential as a source of new and unique hybrids. Preliminary data showed that BC1:S1 lines from GEM 21 (AR16026:S17-66-1-B) has significant variability for extractable starch, protein and oil percentage in hybrid combinations with industry testers. At least 15 GEM-derived lines showed over 101% of check mean yield and test weight while more of these lines showed significant drought tolerance. In 2008, we extended this study to four hundred BC1:S1 lines representing six GEM breeding populations GEM10 (DKB844:S1601-507-1-B-B), GEM3 (CUBA117:S1520-388-1-B), GEM26 (FS8B(T): N1802-35-1-B-B), GEM22 (CHO5015:N12-123-1-B-B), GEM4 (SCR01:N1310-265-1-B-B), and GEM5 (BR52051-N04-70-1) and BC check populations of B73, Mo17, and Iowa Stiff Stalk Synthetic (BSSS).These were tested with two industry testers LH176 and TR3026 x TR2040. In 2009, the testcrosses will be evaluated in four North Dakota locations. The study will show new ways of breeding for developing new and unique early maturing maize competitive hybrids while maintaining genetic variability at high levels and breeding programs open.