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Fred Below Fred Below
Professor of Crop Physiology
Department of Crop Sciences
(217) 333-9745
fbelow@illinois.edu
Stephen Moose Stephen Moose
Assistant Professor of Maize
Functional Genomics
Department of Crop Sciences
(217) 244-6308
smoose@illinois.edu

Genetic Differences in Nitrogen Use by Corn

Nitrogen fertilizer recommendations usually consider that all hybrids have the same N requirements, although it is known that corn genotypes can vary markedly in their response to N. This variation can be in: 1) the amount of N required for optimal productivity; 2) in the timing of N acquisition; 3) in the efficiency of fertilizer N recovery; or, 4) in the utilization of absorbed N to make grain. As part of our ongoing efforts to identify and characterize "NitroGenes", genes and traits that can be used to improve N use of corn, we have evaluated diverse germplasm for differences in N use efficiency (NUE) and its component traits. This germplasm included inbreds, as well as groups of genetically diverse hybrids spanning experimental, historic, and commercial varieties.

We observed large differences among these genotypes in both their overall NUE and in the strategy they used to achieve it. For most of the N use traits, some of the diverse genotypes were superior to the best commercial hybrids, demonstrating that useful genetic variation exists for NUE and its components traits within the corn germplasm. While evaluation of inbreds proved of limited value in either identifying important NUE traits, or in predicting a hybrid's response to N, we often demonstrated better N use in the corresponding hybrid when one of its inbred parents contained germplasm that we expected could harbor genes for improved NUE. One such example was lines derived from Brazilian germplasm that is typically produced under low levels of N. Among the many component N use traits that we evaluated, the ability to produce kernels under low N was particularly important, and is likely to be a key focus of our future evaluations. Having identified genetic variation for NUE and its component traits in corn, the stage is now set for us to apply the methods of functional genomics to identify those genes controlling NUE. We hope that the discovery of genes or pathways that are either associated with or possibly regulate NUE will have utility in corn breeding programs aimed at the development of N efficient hybrids.

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Department of Crop Sciences
College of Agriculture, Consumer and Environmental Sciences
University of Illinois Extension
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