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United States Department of Agriculture

Agricultural Research Service

Title: Characterizing Nitrogen Use Efficiency to Improve Crop Performance in Organic and Sustainable Agricultural Systems

Authors
item Dawson, Julie - WSU
item Huggins, David
item Jones, Stephen - WSU

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 4, 2008
Publication Date: May 10, 2008
Repository URL: http://hdl.handle.net/10113/16663
Citation: Dawson, J.C., Huggins, D.R., Jones, S.S. 2008. Characterizing Nitrogen Use Efficiency to Improve Crop Performance in Organic and Sustainable Agricultural Systems. Field Crops Research. 107:89-101 [doi:10.1016/j.fcr.2008.01.001].

Interpretive Summary: The efficiency with which Nitrogen (N) is used by crop plants is widely studied with the primary goal of increasing yield and yield quality (protein) for each unit of available N. Understanding the components of N use efficiency (NUE) that are under genetic control can assist breeders in improving crop and cropping system performance. There are also aspects of NUE that assess impacts that crops and cropping systems have on the environment. Genetic traits that reduce N losses or crop N requirements can help minimize adverse environmental impacts. In sustainable and organic systems, there is greater reliance on perennial crops, complex rotations and internal nutrient cycling. These differences have large impacts on NUE which in turn affects what crop traits are required to breed for optimal NUE. We reviewed different approaches to assess NUE in cultivated and natural systems, defined new N use efficiency components that target low input and organic systems and identified breeding strategies that may prove useful for evaluating and improving NUE in these farming systems. At this point, the best results have been achieved by breeding in the target system, with high stress levels. This allows breeders to develop populations and lines with speci'c adaptation and temporal stability in such systems. More research is needed on the genetic factors controlling NUE in such systems, and whether the genetic mechanisms differ signi'cantly between high and low fertility environments. The most important avenue for increasing NUE is in balancing N supply with demand, which will require much more knowledge about crop and soil ecology. New NUE efficiency components were defined and integrated into the development of new breeding strategies for sustainable low-input and organic farming systems.

Technical Abstract: Nitrogen use efficiency (NUE) is a widely studied trait in crop plants, with the primary goal of increasing protein and yield per unit of applied nitrogen fertilizer. Understanding the components of NUE that are under genetic control can assist breeders in improving crop performance. There are also aspects of NUE that relate to crop environmental impacts. Genetic traits that reduce N losses or crop nitrogen requirements can help minimize adverse environmental impacts. In sustainable and organic systems, there is greater reliance on perennial crops, complex rotations and internal nutrient cycling which in turn affects crop traits required for optimal NUE. In addition, these systems are generally more challenging to breed for than conventional systems due to environmental heterogeneity, however, it is possible to make genetic gains in such systems. We reviewed different approaches to assess N use efficiency in cultivated and natural systems, defined new N use efficiency components that target low input and organic systems, and identified breeding strategies that may prove useful for these farming systems. At this point, the best results have been achieved by breeding in the target system, with high stress levels. This allows breeders to develop populations and lines with speci'c adaptation and temporal stability in such systems. More research is needed on the genetic factors controlling nitrogen use efficiency in such systems, and whether the genetic mechanisms differ signi'cantly between high and low fertility environments. The most important avenue for increasing NUE is in balancing N supply with demand, which will require much more knowledge about crop and soil ecology. Whether through breeding crops adapted to organic fertilizers and management practices, or improving practices to enhance nutrient cycling in better synchrony with crop demands, much research remains to be done before the factors contributing to optimal NUE are understood and applied in agricultural systems.

Last Modified: 4/19/2014