Expanding the plant economics spectrum with root nitrogen reallocation

Harnessing root nitrogen reallocation (RNR) for optimization of plant productivity commences with positioning RNR in root economics space about which we still know little. We conducted a global synthesis linking RNR to root traits, combined with a two-year 15N-labelling field experiment to position RNR in plant economics spectrum under acidification. RNR correlated negatively with specific root length (SRL) and mycorrhizal colonization globally, suggesting that RNR is a conservative trait. Sedges, grasses and forbs coordinated root traits (e.g., SRL) from acquisitive to conservative and from low to high RNR reliance (and vice versa for their direct-root N uptake) in the 15N-tracing experiment. Specifically, sedges and forbs exhibited the lowest and highest RNR that increased and decreased with acidification, respectively. Grasses cooperated well with mycorrhizas, showing moderate RNR and root traits. Our results demonstrated the significance of RNR in plant growth, and the necessity of ..., A global study for reallocation of N from roots
To position RNR in the root economics space, we compiled a global dataset on N reallocation by searching the keywords of ‘nitrogen reallocation’ OR ‘nitrogen remobilization’ OR ‘nitrogen redistribution’ OR ‘root nitrogen’ using “Web of Science”, “Scopus” and “Google Scholar”. Based on the criteria of RNR quantification, only 15 papers met the merit for inclusion. These selected studies applied either 15N isotope or N budget approaches to quantify RNR (14 versus one study). For the 15N isotope approach, soil available N pool was labelled with 15N tracers directly after defoliation, and thereafter the 15N enrichment of the soil available N pool was used to quantify N uptake from the soil and N remobilization was then estimated as the difference between the N pool in regrown shoots and soil N uptake (Yang et al., 2023). Regarding the N-budget approach, it was also implemented with the facilitation of 15N tracers, where the percentage of N upt..., , | Column | Entry | Value | Unit | Explanation |
| ------ | -------------------------------------------- | --------- | -------- | --------------------------------------------------------------------------------------------------------------------------- |
| A | Geographic coordinate | | | Geographic coordinate of fifteen researches of RNR in global |
| B | RNR | Numerical | % | Nitrogen reallocation from storage organs to new-growing tissues for plant regrowth in global sites |
| C | SRL | Numerical | g·m-1 | Specific root length of plant in global sites ...

通过调控根系氮再分配（root nitrogen reallocation, RNR）以优化植物生产力，其研究起点在于将RNR锚定在根系经济空间框架中，而目前学界对该框架的认知仍较为有限。本研究开展了一项将RNR与根系性状相关联的全球综合分析，并结合为期两年的15N标记田间试验，以明确酸化条件下RNR在植物经济谱中的定位。
全球范围内，RNR与比根长（specific root length, SRL）及菌根定植率呈负相关，表明RNR属于保守型性状。在15N示踪试验中，莎草科植物、禾本科植物与非禾本草本植物的根系性状（如SRL）呈现出从获取型到保守型的协同变化，同时其对RNR的依赖程度从低到高变化（直接根系氮吸收则呈现相反趋势）。具体而言，莎草科植物与非禾本草本植物的RNR分别处于最低与最高水平，且其RNR随酸化程度分别呈上升与下降趋势；禾本科植物则与菌根形成良好协同，表现出中等水平的RNR与根系性状。本研究结果证实了RNR在植物生长中的重要意义，以及……的必要性。【全球根系氮再分配研究】
为明确RNR在根系经济空间中的定位，本研究通过在"Web of Science"、"Scopus"及"Google Scholar"中检索关键词"nitrogen reallocation"或"nitrogen remobilization"或"nitrogen redistribution"或"root nitrogen"，构建了一套全球氮再分配数据集。根据RNR量化标准，最终仅有15篇文献符合纳入标准。入选研究均采用15N同位素法或氮预算法量化RNR（分别为14篇与1篇）。对于15N同位素法，研究人员在植物去叶后直接用15N标记剂标记土壤有效氮库，随后通过土壤有效氮库的15N丰度量化植物从土壤中的氮吸收量，并以再生地上部氮库与土壤氮吸收量的差值估算氮再分配量（Yang等，2023）。而对于氮预算法，研究同样借助15N标记剂开展，其中氮吸收占比……
| 列号 | 条目名称 | 数值类型 | 单位 | 说明 |
| ---- | -------------------------------------------- | --------- | -------- | --------------------------------------------------------------------------------------------------------------------------- |
| A | 地理坐标 | | | 全球15项RNR研究的地理坐标 |
| B | RNR | 数值型 | % | 全球样点中，植物用于再生生长的、从贮藏器官向新生组织转移的氮再分配比例 |
| C | SRL | 数值型 | g·m⁻¹ | 全球样点中植物的比根长 ...