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Heterosis in Compositional, Physical, and Wet-Milling Properties of Adapted × Exotic Corn Crosses¹

¹Journal Paper 18971 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Research project 0178 supported by the Center for Crops Utilization Research, the Iowa Agriculture and Home Economics Experiment Station, and the United States Department of Agriculture. ²Graduate research assistant and professor, Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011. ³Corresponding author. E-mail: ljohnson@iastate.edu Phone: 515-294-0160. ⁴Research Geneticist, USDA-ARS, Corn Insects and Crop Genetics Research Unit, Department of Agronomy, Iowa State University, Ames, IA 50011. ⁵Professor, Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011.

Compositional, physical, and wet-milling properties of 10 corn accessions selected from the Germplasm Enhancement of Maize (GEM) project, two Corn Belt Dent inbreds (B73 and Mo17), and their crosses were compared to determine heterosis among these traits and to gain insight about their genetic control. Crossing the GEM accessions with each inbred increased protein and reduced starch contents. Mean absolute densities and test weights of the crosses were greater than for either parent. Little heterosis was observed in 1,000-kernel weight, and the crosses had similar values to the GEM parents (relatively low). Grain protein contents were greater for the crosses than for the GEM accessions; starch and oil contents of the crosses were intermediate to both parents. The wet-milling properties of the crosses were improved over those of the GEM accessions. Crossing the GEM accessions with B73 greatly increased residual protein content in the recovered starch, whereas values for protein in starch for the GEM × Mo17 crosses were greater than for the GEM accessions and not unlike that of Mo17. High-parent heterosis was greater in the GEM × Mo17 crosses for absolute density, test weight, 1,000-kernel weight, and starch content, but lower for protein and fat contents. GEM × Mo17 crosses yielded greater high-parent heterosis for starch yield and starch recovery, and lower high-parent heterosis for gluten and fiber yields. Mo17 expressed poor wet-milling properties as an inbred but produced superior hybrids compared with B73, which had better wetmilling properties as an inbred.