Farzadfar Soudeh, Knight J Diane, Congreves Kate A
Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada.
Department of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada.
Plant Soil. 2021;462(1-2):7-23. doi: 10.1007/s11104-021-04860-w. Epub 2021 Feb 18.
For more than a century, crop N nutrition research has primarily focused on inorganic N (IN) dynamics, building the traditional model that agricultural plants predominantly take up N in the form of NO and NH . However, results reported in the ecological and agricultural literature suggest that the traditional model of plant N nutrition is oversimplified.
We examine the role of organic N (ON) in plant N nutrition, first by reviewing the historical discoveries by ecologists of plant ON uptake, then by discussing the advancements of key analytical techniques that have furthered the cause (stable isotope and microdialysis techniques). The current state of knowledge on soil ON dynamics is analyzed concurrently with recent developments that show ON uptake and assimilation by agricultural plant species. Lastly, we consider the relationship between ON uptake and nitrogen use efficiency (NUE) in an agricultural context.
We propose several mechanisms by which ON uptake and assimilation may increase crop NUE, such as by reducing N assimilation costs, promoting root biomass growth, shaping N cycling microbial communities, recapturing exuded N compounds, and aligning the root uptake capacity to the soil N supply in highly fertilized systems. These hypothetical mechanisms should direct future research on the topic. Although the quantitative role remains unknown, ON compounds should be considered as significant contributors to plant N nutrition.
一个多世纪以来，作物氮营养研究主要集中在无机氮（IN）动态方面，构建了传统模型，即农业植物主要以NO和NH的形式吸收氮。然而，生态和农业文献报道的结果表明，植物氮营养的传统模型过于简化。
我们研究有机氮（ON）在植物氮营养中的作用，首先回顾生态学家关于植物吸收有机氮的历史发现，然后讨论推动该研究进展的关键分析技术（稳定同位素和微透析技术）的进步。同时分析土壤有机氮动态的当前知识状态以及农业植物物种吸收和同化有机氮的最新进展。最后，我们考虑农业背景下有机氮吸收与氮利用效率（NUE）之间的关系。
我们提出了几种有机氮吸收和同化可能提高作物氮利用效率的机制，例如通过降低氮同化成本、促进根系生物量增长、塑造氮循环微生物群落、重新捕获渗出的氮化合物以及在高施肥系统中使根系吸收能力与土壤氮供应相匹配。这些假设机制应指导该主题的未来研究。尽管其定量作用尚不清楚，但有机氮化合物应被视为植物氮营养的重要贡献者。
