Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China.
Ann Bot. 2023 Oct 18;132(2):217-227. doi: 10.1093/aob/mcad095.
Plant nitrogen (N) acquisition via arbuscular mycorrhizal fungi (AMF) serves as a dominant pathway in the N nutrition of many plants, but the functional impact of AMF in acquisition of N by wetland plants has not been well quantified. Subtropical lake-wetland ecosystems are characterized by seasonal changes in the water table and low N availability in soil. Yet, it is unclear whether and how AMF alters the N acquisition pattern of plants for various forms of N and how this process is influenced by soil water conditions.
We performed a pot study with Carex thunbergii that were either colonized by AMF or not colonized and also subjected to different water conditions. We used 15N labelling to track plant N uptake.
Colonization by AMF had little effect on the biomass components of C. thunbergii but did significantly affect the plant functional traits and N acquisition in ways that were dependent on the soil water conditions. The N uptake rate of AMF-colonized plants was significantly lower than that of the non-colonized plants in conditions of low soil water. A decreased NO3- uptake rate in AMF-colonized plants reduced the N:P ratio of the plants. Although C. thunbergii predominantly took up N in the form of NO3-, higher water availability increased the proportion of N taken up as NH4+, irrespective of the inoculation status.
These results emphasize the importance of AMF colonization in controlling the N uptake strategies of plants and can improve predictions of N budget under the changing water table conditions in this subtropical wetland ecosystem.
植物通过丛枝菌根真菌（AMF）获取氮（N）是许多植物 N 营养的主要途径，但 AMF 在湿地植物获取 N 方面的功能影响尚未得到很好的量化。亚热带湖泊湿地生态系统的特点是地下水位季节性变化和土壤中 N 供应不足。然而，目前尚不清楚 AMF 是否以及如何改变植物对各种形式 N 的获取模式，以及这一过程如何受到土壤水分条件的影响。
我们进行了一项与苔草的盆栽研究，这些苔草要么被 AMF 定殖，要么没有被定殖，并同时进行了不同的水分处理。我们使用 15N 标记来追踪植物的 N 吸收。
AMF 的定殖对苔草的生物量组成影响不大，但对植物功能特性和 N 吸收的影响显著，且这种影响方式依赖于土壤水分条件。在土壤水分低的情况下，AMF 定殖植物的 N 吸收速率明显低于非定殖植物。AMF 定殖植物对 NO3-吸收速率的降低降低了植物的 N:P 比。尽管苔草主要以 NO3-的形式吸收 N，但较高的水分供应增加了以 NH4+形式吸收的 N 的比例，而与接种状态无关。
这些结果强调了 AMF 定殖在控制植物 N 吸收策略方面的重要性，并可以提高在这种亚热带湿地生态系统地下水位变化条件下对 N 预算的预测。
