Changes in parentage and genetic diversity of widely used maize hybrids grown in the Northern United States and France from 1930 to the present [Zea mays L.]
2006
Smith, J.S.C. | Desbons, P. | Goberty, J. | Niebur, W.S.
Studies of cultivated varieties historically used in agriculture provide measures of genetic gain and help to identify the morphological features, physiological characteristics, and ultimately, the germplasm which contributes those gains. The extent and manner in which genetic diversity is used determines the amount and sustainability of productivity gains. France and the Northern Corn Belt of the US represent contrasting regions of maize (Zea mays L.) agriculture which nonetheless share germplasm and challenges associated with breeding at the temperate frontiers of maize environmental adaptedness. We used pedigree data to document germplasm deployed in maize hybrids associated with productivity gains in two regions of France (from 1950s to the present) and in the Northern US Corn Belt (from 1930s to the present). Sixty-six founder sources were identified. Six founders (Pyrenees Flint, Leaming, Minnesota 13, Iodent, Reid Yellow Dent and Wisconsin 25) were principal contributors at 5% per decade in one or more regions. Minnesota 13, Iodent and Reid Yellow Dent were principal contributors in all three regions. Twenty-six founders were moderate contributors (mean of 1 - 4.9% per decade). Only three of these founders (Lancaster Low Breakage, Lindstrom Long Ear and Osterland) were present in each region. Major changes in germplasm backgrounds occurred for each region in nearly every decade. Associations of hybrids on the basis of pedigrees showed that most hybrids used in Southern France differed from hybrids used in Northern France. Several hybrids used in Southern France were associated with hybrids used in Northern Iowa. One important pedigree component in all three regions (Iodent) could have been lost had it not been for 50 years of breeding that occurred following Iodent's entry in the 1922 Iowa State yield trials
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