Breeding Potential of Semidwarf Corn for Grain and Forage in the Northern U.S. Corn Belt

Abstract

Conventional, nondwarf corn {Zea mays L.) hybrids grown in the northern U.S. Corn Belt are typically >2 m tall and have a 75-to 100-d relative maturity (RM). Our objectives were to assess the potential of open-poHinated C0P0P1 semidwarf corn for grain and forage production, estimate genetic variances and heritability in C0P0P1, and develop COPOP1 subpopulations that exhibit heterosis. In 2005 and 2006, we evaluated C0P0P1 with four commercial, nondwarf hybrids at three plant population densities. Grain yield of open-pollinated COPOP1 was about half of the mean yieid of the conventionai hybrids. However, C0P0P1 had lower grain moisture (equivalent to 62 d RM) and better forage quality than the commercial hybrids. In 2007, C0P0P1 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 C0P0P1) and Cycle 1 testcrosses, nine semidwarf hybrids, C0P0P1, and three commercial hybrids were evaluated at two plant population densities. Grain yieid and most agronomic and forage traits did not improve between Cycle 0 and Cycle 1 in either testcross population. None of the semidwarf hybrids had higher grain yieids than C0P0P1. While semidwarf C0P0P1 can serve as a souroe of useful variation for improving elite germplasm in the northern U.S. Corn Beit, further selection in C0P0P1 must be done to deveiop improved semidwarf populations. Abbreviations: ASI, anthesis-silking interval; BSSS, Iowa Stiff Stalk Synthetic; IVTD, in vitro true digestibility; NDF, neutral detergent fiber; NDFD, neutral detergent fiber digestibility; NIRS, near-infrared reflectance spectroscopy; RM, relative maturity. I N CORN {Zea mays L.), genes such as reduced plant 1 {rdl), brachytic 2 {br2), and compact plant {ci) cause dwarfing (Nelson and Ohlrogge, 1957;Scott and Campbell, 1969;Modarres et al., 1997b;Neuffer et al., 1997). Semidwarf corn may have characteristics that make it suitable for grain and forage production in short-season environments (Dijak et al., 1999;Coors and Lauer, 2001). In particular, the limited heat units in short-season environments reduce grain yield and lessen the probability of the crop reaching physiological maturity in a given year. Semidwarf hybrids have required 10% fewer heat units than conventional hybrids to reach anthesis (Dijak et al., 1999) and generally reach physiological maturity earlier than conventional cultivars (Modarres et al., 1997a). Like semidwarf wheat {Triticum aestivum L.; Vogel et al., 1963), semidwarf sorghum {Sorghum bicolor L.; Windscheffel et al., 1973), and semidwarf rice {Oryza sativa L.; Hedden, 2003), semidwarf corn may be less prone to stalk and root lodging due to the shorter stalks and lower ear placement (Dijak et al., 1999). Semidwarf corn has the potential to produce high-quality forage due to its high ear-to-stover ratio, although dry matter y...

Assessing Tillage Systems for Reducing Ammonia Volatilization from Spring-Applied Slurry Manure

“…Silage yield was adjusted to 70 percent moisture, respectively. Ear-to-stover ratio was determined based on dry weights and used as corn silage quality criteria (Schaefer, Sheaffer, and Bernardo 2011).…”

“…No significant differences in agronomic N efficiency were found among tillage treatments in 2012. Because of the greater energy content of grains, high-quality forage is often equated with high ear-to-stover ratio (Schaefer, Sheaffer, and Bernardo 2011). No significant differences in ear-to-stover ratio among tillage systems were observed in 2011 or 2012 (Table 4).…”

Avaliação de genótipos de milho, com ou sem cobertura nitrogenada, em condições de semeadura distintas

“…Schaefer et al (2011) encontraram menor produção de grãos de populações em relação aos híbridos justificando, primeiro pela condição genética (ser uma população) e segunda pela população utilizada por esses autores ter um ciclo de maturação menor em relação aos híbridos utilizados. Assim, pode haver tendência de populações apresentarem menor potencial de produção de grãos frente aos híbridos, porém, com potencial de produção de massa verde da planta maior ou similar.…”

Genomewide Selection to Introgress Semidwarf Maize Germplasm into U.S. Corn Belt Inbreds

“…DC1 and DC2 were developed by one generation of selfing from COPOP1 and were selected based on their performance in yield trials at the University of Minnesota (Schaefer et al, 2011). DC1 and DC2 were developed by one generation of selfing from COPOP1 and were selected based on their performance in yield trials at the University of Minnesota (Schaefer et al, 2011).…”

“…dwarfing but, as an early maturing population, also has low grain yield (Schaefer et al, 2011). our objectives were to determine (i) if genomewide selection is useful for the rapid improvement of an exotic × adapted cross, (ii) if genomewide selection is more effective than phenotypic backcrossing for a trait with major genes, and (iii) the extent to which the high grain yield of nondwarf maize can be combined with the reduced stature and adaptability to high plant population densities of semidwarf maize.…”