Background of U.S. Hybrid Corn II

Understanding the history of a crop helps plant breeders select. This paper supplements and corrects Background of U.S. Hybrid Corn (Zea mays L., Crop Sci. 39:601–626). I explain which open‐pollinated cultivars and landmark inbreds persisted into today's hybrids and attempt to explain how and why. I briefly discuss human (artificial) selection, natural selection, and food production. Pedigree background frequencies from 33 elite, 1990s era inbreds directly estimate about 40% of U.S. hybrid corn hectarage and indirectly estimate the rest. I've searched historical records to trace the succession of cultivars and inbreds. Reid Yellow Dent is 51% of the documented U.S. hybrid corn background (Iodent Reid, 13%; Troyer Reid, 12%; Osterland Reid, 11%; Stiff Stalk Synthetic, 8%; Reid per se, 4%; and Funk Reid, 3%). Minnesota 13 is 13%, Lancaster Sure Crop is 13%, Northwestern Dent is 5%, and Leaming Corn is 5%. Five widely adapted, century‐old, open‐pollinated cultivars surpassed in use tens of thousands of genetically divergent cultivars to account for 87% of the known background of today's U.S. hybrid corn. Adaptedness mattered; U.S. corn breeders are adapting a tropical crop to a temperate climate. New, diverse background sources will probably be better adapted to longer daylengths, cooler minimum temperatures, drought, shorter seasons, and improved crop production practices. Selecting for adaptation to these conditions and to improved agronomic production practices will continue to increase yield. Traditional corn breeding methods will continue to accommodate climate change. Plant breeding and crop production research provides plentiful food in the USA.