Function of mycorrhiza in the competition for water and nitrogen

本研究旨在探讨外生菌根(EM)群落在山毛榉氮素吸收中的作用。并了解干旱对这些功能的影响。利用15N标记技术研究山毛榉和外生菌根在田间和控制条件下的氮素吸收，以探讨EM 15N的增加与植物氮素吸收的关系。将从一系列干燥和潮湿的地点合成特定地点的EM群落。干旱胁迫将作为调节根系碳供应的一种手段，从而影响EM的竞争关系。将根据物种收集EM，并确定其丰度并与N吸收相关。为了剖析菌根效应，非菌根山毛榉也将被研究。15N的富集率和吸收速率将在受控的实验EM-山毛榉组合中与选定的真菌物种进行分析，以找出不同EM物种在充分浇水和干燥条件下向山毛榉供应氮素的能力是否存在差异。

The goal of this proposal is to investigate the function of ectomycorrhizal (EM) communities for nitrogen acquisition of beech (Fagus sylvatica L.) and to understand how these functions are affected by drought. 15N labelling will be used to investigate N uptake of beech plants and ectomycorrhizas under field und controlled conditions to explore relationships between EM 15N enrichment and plant N uptake. Site-specific EM communities from a range of dry and moist sites will be synthesized. Drought stress will be applied as a means to modulate carbon supply to roots, thereby affecting the competitive relations of EM. EM will be collected according to species and their abundance will be determined and related to N-uptake. To dissect the mycorrhizal effect, non-mycorrhizal beeches will also be studied. 15N enrichment and uptake rates will be analysed in controlled experimental EM-beech associations with selected fungal species to find out if differences in the abilities of different EM species exist to supply beech with N under well watered and dry conditions.