Schaefer, Christopher Michael2011-04-212011-04-212010-09http://purl.umn.edu/103044University of Minnesota M.S. thesis. October 2010. Major: Applied plant sciences. Advisor: Rex N. Bernardo. 1 computer file (PDF); iv, 32 pages.Conventional, non-dwarf corn (Zea mays L.) hybrids grown in the northern U.S. Corn Belt are typically more than 2 m tall and have a 75-100 day relative maturity (RM). Our objectives were to assess the potential of open-pollinated COPOP1 semi-dwarf corn for grain and forage production, estimate genetic variances and heritability in COPOP1, and develop COPOP1 subpopulations that exhibit heterosis. In 2005 and 2006, we evaluated COPOP1 with four commercial, non-dwarf hybrids at three plant population densities. Grain yield of open-pollinated COPOP1 was about half of the mean yield of the conventional hybrids. However, COPOP1 had lower grain moisture (equivalent to 62 days RM) and better forage quality than the commercial hybrids. In 2007, COPOP1 was evaluated for performance when crossed to two divergent inbred testers, LH227 and LH295. Heritability was significant for grain moisture, plant height, and ear height in testcrosses to both testers but was significant for grain yield only in testcrosses to LH227. In 2009, bulk Cycle 0 (i.e., original COPOP1) and Cycle 1 testcrosses, nine semi-dwarf hybrids, COPOP1, and three commercial hybrids were evaluated at two plant population densities. Grain yield and most agronomic and forage traits did not improve between Cycle 0 and Cycle 1 in either testcross population. None of the semi-dwarf hybrids had higher grain yields than COPOP1. While semi-dwarf COPOP1 can serve as a source of useful variation for improving elite germplasm in the northern U.S. Corn Belt, further selection in COPOP1 must be done to develop improved semi-dwarf populations.en-USNon-dwarf corn (Zea mays L.)northern U.S. Corn BeltCOPOP1Grain yieldSemi-dwarf hybridsElite germplasmApplied plant sciencesForage productionThesis or Dissertation