Heterotic Patterns among Ten Corn Belt and Exotic Maize Populations

Abstract

Maize breeders are concerned with the narrow base of Corn Belt germplasm and the wide use of one heterotic pattern, ‘Reid’ × ‘Lancaster’, in maize (Zea mays L.). Knowledge of other heterotic patterns can contribute to a broadening of the commercial germplasm base. The study was carried out to evaluate heterotic combinations among seven yellow‐endosperm populations—‘BSSS(R)C10’,‘BSK(HI)C8 Syn 3’, ‘BS16(S)C3 Syn 2’, ‘Mexican Dent’, ‘Leaming’, ‘Midland’, among three white‐endosperm populations—‘Pride of Sameline’, ‘Johnson County White’, ‘Potchefstroom Pearl’, and among all 10 populations. In 1985, the 10 populations, their diallel crosses, and 26 checks were evaluated in a 9 × 9 partially balanced lattice with two replications in seven locations. Sources of variation for entries, populations, and general combining ability (GCA) were significant for root lodging, stalk lodging, ear height, days‐to‐pollen shed, days‐to‐silking, moisture content, and yield. Specific combining ability (SCA) mean squares were significant only for ear height. BSSS(R)C10 had the highest GCA effect for yield of all the populations tested. The BSSS(R)C10 × Mexican Dent had the highest yield of 8.77 Mg ha−1, although the four top‐yielding crosses did not differ significantly. This yield was not significantly higher than the check B73 × Mo17, but was significantly higher than BSSS(R)C10 × Lancaster, which represents the heterotic pattern Reid × Lancaster. There were no significant yield differences among the white‐endosperm population crosses. BSSS(R)C10 × Mexican Dent and Midland × BSK(HI)C8 Syn 3 should be evaluated for possible hybrid combinations.

Open-Pollinated vs. Hybrid Maize Cultivars

“…Sprague noted "it appears that the ear-to-row method of selection for yielding ability was discredited not because of genetic limitations of the method, but because of the inadequate field plot technique" [16]. Research after Richey's 1922 conclusion showed recurrent selection and varietal hybrids could be very successful at increasing maize yields after all, although they could not provide cultivars with the yields of the best hybrids [35,47,81,95,119,120,[126][127][128][129][130][131].…”

“…Advantages of this approach could be higher yields than possible with populations per se, cheap hybrid seed given the levels of production that may be possible with populations compared to expected yields of inbred parent lines, and the possibility for ongoing improvement of the parent populations and their hybrids on-farm. Disadvantages could include separate seed production requirements, likely lower yield than single cross hybrids [129], and lower uniformity than that observed in single cross hybrids.…”

Heterosis and heterotic patterns among maize landraces for forage

“…According to Crossa et al (1990), in the Americas there is a tremendous genetic diversity in maize, as a result of thousands of years of evolution under domestication and hybridization, which has not been effectively exploited. Many authors have suggested the usefulness of incorporating exotic germplasm into breeding programs (Eberhart 1971, Hallauer and Miranda 1981, Oyerbides-Garcia et al 1985, Holley and Goodman 1988, Mungoma and Pollak 1988, Iglesias and Hallauer 1989, Pollak et al 1991, Michelini and Hallauer 1993, Rodrigues and Chaves 2002, Carena 2005, Soengas et al 2006. Thompson (1968) found that a group of exotic and semi-exotic populations yielded on average 28% more digestible dry matter than adapted hybrids, and Stuber LC Gabriel et al (1986) suggested that some semi-exotic materials might be suitable for silage, given their good grain production and great vegetative development.…”

Incorporating different proportions of exotic maize germplasm into two adapted populations

“…Most results relate to the usefulness of crosses between exotic x adapted germplasm (Eberhart, 1971;Gerrish, 1983;Oyervides-Garcia et al, 1985;Holland and Goodman, 1995), the estimates of genetic parameters (Goodman, 1965;Hallauer and Sears, 1972;Sheata and Dhawan, 1975;Santos and Miranda Filho, 1992), and the determination of heterotic patterns (Holley and Goodman, 1988;Mungoma and Pollak, 1988;Pollak et al, 1991;Godshalk and Kauffmann, 1995;Uhr and Goodman, 1995;Eschandi and Hallauer, 1996).…”