NDSU EarlyGEM: Incorporating Tropical and Temperate Elite Exotic Germplasm to Increase the Genetic Diversity of Short-Season Maize

Abstract

The NDSU EarlyGEM or the Early Germplasm Enhancement of Maize (Zea mays L) is a long-term incorporation program designed to increase the genetic diversity of US northern maize hybrids. Exotic GEM breeding crosses derived from two temperate accessions, three tropical accessions and a tropical hybrid along with temperate US lines B73, Mo17, and Iowa Stiff Stalk Synthetic (BSSS) used as checks, were adapted to short-seasons and incorporated via a modified backcross (BC) procedure. The objective of this research was to test whether exotic derived crosses could be quickly adapted and incorporated to increase the genetic diversity of early maturing maize hybrids as compared to temperate US check lines. Exotic testcrosses with testers belonging to opposite heterotic groups were tested in five North Dakota environments and two years (2009 and 2010). Among 236 experimental testcrosses, 64 were statistically not different (LSD, 0.05) to industry hybrids for grain yield. BC derived lines from BR52051, CHO5015, DKB844 produced hybrids with low grain moisture at harvest (<87 RM) and high yield as compare to US lines. The derived lines of accessions SCRO1, BR52051, CHO5015 and CUBA117 produced hybrids with high grain oil (49 g kg-1 vs. 41 g kg-1) and grain protein (102 g kg-1 vs. 91 g kg-1) contents compared to checks. These results clearly showed that the exotic incorporations are the sources of unique new alleles for adaptation, yield, and quality traits for early maturing maize not present in existing US commercial germplasms and genome sequences (e.g. B73, Mo17, and BSSS). The NDSU EarlyGEM program is a source of unique and elite alleles and products.