About this Research Topic
Inefficient use of nitrogen (N) fertilizers by crops and the resulting N losses as nitrous oxide, ammonia, and NOx to air, and as nitrates or ammonium ions to water, are serious economic and environmental concerns. The Frontiers 2018/19 Report of the UN Environment identified reactive nitrogen as one of five emerging threats facing the planet, and the fourth UN Environment Assembly adopted a resolution for “Sustainable nitrogen management”.
Improvement of crop nitrogen use efficiency (NUE) can only be partially achieved through slow-release fertilizers, legume-based rotations, biofertilizers, or precision farming methods, unless the plant level NUE is improved biologically. It is also the only option until the genetic transfer of N-fixing ability from microbes to crop plants materializes. The lack of a biologically measurable definition of NUE and the poor characterization of its phenotype and genotype has hampered crop improvement so far. Therefore, many unsettled issues remain despite recent progress in the field.
This Research Topic invites articles that identify the phenotype/genotype for NUE, demonstrate improved NUE, or significantly progress the physiological, biochemical, genetic, genomic, or molecular understanding of the plant N-response and NUE. Descriptive articles, or mere reporting of data, will not be considered, unless they provide functional or mechanistic insights into the plant NUE or NUE improvement. Accordingly, Original Research and Review articles are welcome in the following areas:
• Biological differentiation between N-response and NUE and/or the development of a biologically robust definition of NUE. Manuscripts may rigorously evaluate the existing definitions or propose new definitions along with underlying biological evidence.
• Characterization of the NUE phenotype, either of universal value for all plants/N-forms, or specific crop types, or N-forms such as ammonium salts, nitrates, or urea.
• Characterization of the NUE genotype, including identification of nuclear or organellar genes involved and how they bring about NUE or their validation as candidate genes for improving NUE using mutants/transgenics.
• Omics approaches for molecular/genetic characterization of NUE, backed by a phenotypic basis for the chosen germplasm, especially for genome-wide association mapping.
• Functional characterization and/or quantification of the contribution of endophytic microorganisms to crop plants’ N-budget and evaluation of the relative potential of the plant and microbial genetics in NUE improvement.
• The effect of interactions between the crop and its external biotic and abiotic environment on NUE including evaluation of N-losses, interaction with other nutrients/stresses, and their optimization in the cropping/farming system.
This article collection is recognized by the International Nitrogen Initiative (INI) as a resource to highlight the importance of the Nitrogen Use Efficiency in crops
Keywords: Nitrogen use efficiency, Sustainable nitrogen management
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.
