作物利用土壤资源时根系代谢成本与根构型和解剖特征紧密相关，在作物养分吸收、产量形成和资源利用效率中可起着重要作用，尤其是在养分有限条件下。因此，基于根代谢成本假说，本项目利用盆栽和大田试验，在不同施氮量下，(1)研究水稻根系构型和解剖特征响应特征，阐明施氮量对根系建成和维持成本的影响及其与产量形成和氮吸收利用效率的关系；(2)研究水稻根系氮吸收和同化主要过程的变化，阐明施氮量对根氮代谢的影响，阐明根氮代谢成本与氮吸收利用效率关系，揭示“根系建成—氮成本—氮代谢关键过程—氮吸收利用效率”间的内在联系；(3)研究水稻根系碳代谢主要过程的变化，阐明施氮量对根碳代谢的影响，研究根系碳代谢成本与氮吸收利用效率关系，揭示“根系建成—碳成本—碳代谢关键过程—氮吸收利用效率”间的内在联系。项目可从根代谢成本角度来揭示水稻氮高效吸收利用的生物学机制和途径，为减氮增效栽培技术研发和新品种选育提供理论支撑。

Crop root metabolic costs of soil exploration are closely associated with root architectural and anatomical phenes, and are of great significance for nutrient absorption, grain yield formation, and resource efficiency, especially under limited nutrient supply. Therefore, based on the root metabolic costs，the project will be conducted under different nitrogen applications in pot and on-farm field experiments, (1) to investigate the responses of root architectural and anatomical phenes to nitrogen applications, reveal the effects of nitrogen applications on the costs of root construction and maintenance, and reveals the relationships of root metabolic costs with nitrogen use efficiency and yield formation；(2) to investigate the changes in key processes of nitrogen absorption and assimilation, and elucidate the effects of nitrogen applications on costs for nitrogen metabolism and its associations with nitrogen use efficiency, further outlines the associations among root construction and maintenance, nitrogen cost, nitrogen metabolic processes, and nitrogen use efficiency; (3) to clarify the changes in key processes of carbon metabolism, and reveal the effects of nitrogen applications on costs for carbon metabolism and its associations with nitrogen use efficiency, further presents the associations among root construction and maintenance, carbon cost, carbon metabolic processes, and nitrogen use efficiency. These studies may theoretically explain the biological mechanism underlying nitrogen use efficiency based on root metabolic costs, and provide rationales and approaches for developing resource efficient variety and practical technology that needs less nitrogen application and achieves high efficiency in rice production.