Heterosis in compositional, physical, and wet-milling properties of adapted x exotic corn crosses

Compositional, physical, and wet-milling properties of 10 corn accessions s elected from the Germplasm Enhancement of Maize (GEM) project, two Corn Bel t Dent inbreds (B73 and Mo17), and their crosses were compared to determine heterosis among these traits and to gain insight about their genetic contr ol. Crossing the GEM accessions with each inbred increased protein and redu ced starch contents. Mean absolute densities and test weights of the crosse s were greater than for either parent. Little heterosis was observed in 1,0 00-kernel weight, and the crosses had similar values to the GEM parents (re latively low). Grain protein contents were greater for the crosses than for the GEM accessions; starch and oil contents of the crosses were intermedia te to both parents. The wet-milling properties of the crosses were improved over those of the GEM accessions. Crossing the GEM accessions with B73 gre atly increased residual protein content in the recovered starch, whereas va lues far protein in starch for the GEM x Mo17 crosses were greater than for the GEM accessions and not unlike that of Mo17. High-parent heterosis was greater in the GEM x Mo17 crosses for absolute density, test weight, 1,000- kernel weight, and starch content, but lower for protein and fat contents. GEM x Mo17 crosses yielded greater high-parent heterosis for starch yield a nd starch recovery, and lower high-parent heterosis for gluten and fiber yi elds. Mo17 expressed poor wet-milling properties as an inbred but produced superior hybrids compared with B73, which had better wet-milling properties as an inbred.