The stimulation effect of elevated [CO₂] (e[CO₂]) on plant growth is modulated by nitrogen (N) availability, yet the mechanisms of this modulation under patchy N supply remain largely elusive. This study aimed to investigate the mechanisms by which patchy nutrient supply in the root-zone influence on N uptake, partitioning and use efficiency of tobacco plants (Nicotiana tabacum L.) grown under e[CO₂]. A split-root pot experiment was conducted on tobacco plants grown at ambient (a[CO₂], 400 μmol L⁻¹) and e[CO₂] (800 μmol L⁻¹) conditions during anthesis. Plants were subjected to two fertilizer levels [0 and 113-29-214 (N-P-K) mg kg⁻¹ soil] and three fertilization regimes (partial root-zone fertilization, PRN, couple root-zone fertilization, CRN and no fertilization, CK). Elevated [CO₂] significantly decreased N concentrations in all tobacco organs, with the greatest reduction in leaves. Positive responses of tobacco biomass and NUE to e[CO₂] were recorded, and a large amount of ¹⁵N labelled fertilizer-N was partitioned to stems at the expense to leaves. Compared to the partially fertilized root, an equal N concentration was observed in the non-fertilized root. In addition, compared with CRN, PRN increased the root exudates of sugar and organic acid; however, the increased root biomass by nutrient patchiness did not enhance plant total N uptake. Collectively, e[CO₂] could sustain N assimilation and distribution of tobacco plants in response to natural heterogeneous nutrient available in the soil caused by patchy fertilization.

中文翻译：

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CO2 升高和养分斑块性交互影响花期烟草的形态、氮吸收、分配和利用效率

升高的 [CO ₂ ] ( e [CO ₂ ]) 对植物生长的刺激作用受氮 (N) 有效性的调节，但在零散的 N 供应下这种调节的机制在很大程度上仍然难以捉摸。本研究旨在探讨根区不均匀的养分供应对e [CO ₂ ]下生长的烟草植物( Nicotiana tabacum L.)的N 吸收、分配和利用效率的影响机制。对在环境 ( a [CO ₂ ], 400 μmol L ^-1 ) 和e [CO ₂ ] (800 μmol L ^-1) 在开花期的条件。植物经受两种肥料水平[0和113-29-214（NPK）mg kg ^-1土壤]和三种施肥方案（部分根区施肥，PRN，一对根区施肥，CRN和不施肥，CK） . 升高的 [CO ₂ ] 显着降低了所有烟草器官中的 N 浓度，其中叶片的降低幅度最大。记录了烟草生物量和 NUE 对e [CO ₂ ] 的正响应，大量¹⁵N 标记的肥料-N 被分配到茎中而牺牲了叶子。与部分受精根相比，在未受精根中观察到相同的氮浓度。此外，与CRN相比，PRN增加了糖和有机酸的根系分泌物；然而，营养斑块增加的根生物量并没有增加植物的总氮吸收。总的来说，e [CO ₂ ] 可以维持烟草植物的 N 同化和分布，以响应由斑块施肥引起的土壤中可用的天然异质养分。