Plant-soil-microbe interactions in phytomanagement systems: Influences of cadmium and nitrogen on rhizosphere microbial communities and growth of native plant species in agricultural systems

植物管理和耕作系统在全世界越来越重要。在本研究中，杨树和柳树将与本地植物物种相结合，进一步完善农场管理系统。选择与农业系统相关的两种常见污染物（镉和氮），从植物修复及其在污染农业土壤中的积累效率方面进行了研究。由于植物与微生物的相互作用在植物管理系统中起着重要作用，一个重点将是在污染土壤上生长的植物根际微生物群落的变化。为了评估植物特定微生物群落结构的这种变化，磷脂脂肪酸（PLFA）将作为一种适当的工具，因为它们存在于所有活细胞中，并在细胞死亡后迅速降解。结果将与基于DNA的微生物群落分析进行比较。此外，植物组织的萜烯、类黄酮和脂质分析将提供对植物响应不同污染物的生理变化的见解。在收获前施加13CO2脉冲，将进一步研究植物代谢中的生理变化以及污染物对根际碳转运。在这种情况下，将比较PLFA和DNA的稳定同位素探测，并进一步对植物组织进行13C分析。为了解决植物管理系统的重点问题，将进一步分析植物各部分（根、茎、叶、果实和种子）的镉和氮含量。高度污染的植物组织可以被燃烧用于生产沼气，随后堆肥用于循环利用。氮含量高但镉含量不显著增加的植株部位在冬季可作为饲料原料；将其用于商业目的是可能的，并将在本研究计划中讨论。

Phytomanagement and Farming systems are of increasing importance throughout the world. In the present study, poplar and willow plants will be combined with native plant species, to further improve farm management systems. Two common contaminants (Cadmium and Nitrogen) with relevance to agricultural systems have been chosen to investigate the plants in terms of phytoremediation and its accumulation efficiency in contaminated agricultural soil. Since plant-microbe interactions play a major role in phytomanagement systems, one focus will be on microbial community shifts in the rhizosphere of plants growing on contaminated soil. To assess such changes in a plant specific microbial community structure, phospholipid fatty acids (PLFA) will serve as an adequate tool, since they are present in all living cells and rapidly degraded after cell death. Results will be compared with DNA based microbial community profiling. Furthermore, terpene, flavonoid and lipid analyses of plant tissue will provide insight into physiological shifts of plants in response to the different contaminants. A 13CO2 pulse applied to the experiment before harvest will provide further investigations of physiological shifts within plant metabolism and carbon translocation into the rhizosphere with respect to the contaminant. In this context, stable isotope probing of PLFA and DNA will be compared, and further 13C analyses of plant tissues carried out. To address the focus of phytomanagement systems, further analyses of plant parts (roots, stem, leaves, fruit and seeds) will be analysed for Cadmium and Nitrogen content. Highly contaminated plant tissues may be burned for biogas production and subsequently composted for recycling. Plant parts with high Nitrogen contents but no significant increase in Cadmium can be used as fodder material during winter periods; the use for commercial purposes may be possible and will be addressed within the present research proposal.