中国典型草地有毒植物分泌土壤硝化抑制剂的机制研究

草原有毒植物无法食用，一直被认为是草原生产力的严重障碍。然而，有毒植物是草原长期进化的结果，是生物多样性无可替代的组成部分，具有存在合理性。土壤氮素是植物生长的关键营养元素，有毒植物分泌特殊次生代谢产物，抑制土壤氨氧化过程，减少土壤硝态氮含量，提高铵氮养分利用率，减少N2O的排放，维系草原植物生产力。因此，研究有毒植物次生代谢产物对硝化微生物抑制特征，将有利于开发优良牧草的新型硝化抑制剂，提高N素利用率，降低草原温室气体N2O排放量。为此，本项目拟在青藏高原高寒草甸原位自然条件下，研究代表性有毒植物对草地土壤氨氧化过程和N2O排放通量的可能抑制效果；利用微宇宙培养实验，评估有毒植物根系分泌物的潜在生物硝化抑制及其温室气体N2O减排的效果。预期成果将有利于理解草地有毒植物存在合理性及其根系分泌物作为生物硝化抑制剂的过程机理，建立有毒植物生物硝化抑制剂数据库，为提升草原生产力提供理论依据。

Poisonous plants in grasslands are unpalatable to grazing animals, and have long been considered a serious obstacle to the improvement of animal husbandry productivity. However, poisonous plants are a net result of long-term evolution in natural grasslands, and their existence may be crucial for biodiversity. For example, poisonous plants are likely to secrete special compounds inhibiting soil ammonia oxidation, improving plant N efficiency while reducing N loss and greenhouse gas N2O emission. In this proposal we therefore aim to: (1) determine the potential inhibition dynamics of soil nitrification by typical poisonous plants such as Stellera patches to assess their potential to improve N utilization efficiency and to mitigate N2O emissions by conducting direct field measurements in the typical grassland of the Qinghai-Tibet Plateau in China; (2) develop a catalogue of novel biological nitrification inhibition (BNI) compounds that can be used in Agricultural N2O mitigation efforts globally by conducting microcosm studies. The expected outputs will help to better rationalize the presence of toxic plants in grasslands, and the mechanism by which their roots exudate (BNI), establish a database of toxic plant biological nitrification inhibitors, and provide an important theoretical basis for the development of sustainable grassland productivity.