Senescence and nitrogen remobilization at plant level as affected by carbon and nitrogen source variation

氮供应的减少和大气二氧化碳浓度的升高都减少了营养组织中可用于籽粒/种子灌浆的氮量。然而，绿色叶与较低的N含量，由于CO2富集的生理功能完全的碳增益方面，因为他们减少的N含量表示的生理适应和优化的N分配的光合机构内增加的C供应。该项目的工作假设是，在叶片衰老过程中具有改善的N再动员的作物改良系将显示出改善的氮利用效率和氮收获指数，但不会克服由CO2升高引起的C和N获取之间的不平衡。根据先前对油菜的观察，当植物已经处于生殖阶段时，CO2富集也有望潜在地启动营养生长。为了验证这些假设，将进行不同的N和CO2供应下的油菜和大麦的生长实验。在整个生命周期的N和C的收购，再动员和再分配将进行评估，涉及15 N作为示踪剂。实验将涉及最近的品种的改良系和野生型，但也有不同的粮食/种子氮含量和氮收获指数的老品种。关键词：衰老，氮再动员，氮利用效率，氮收获指数，基因型，大气二氧化碳浓度升高。

Reduced nitrogen supply and elevated atmospheric carbon dioxide concentrations both reduce the amount of nitrogen available for grain/seed filling from pools in vegetative tissues. However, green leaves with lower N content due to CO2 enrichment are physiologically fully functional in terms of carbon gain since their reduced N content represents a physiological adaptation and optimization of N allocation within the photosynthetic apparatus to increased C supply. The working hypotheses of this project are that modified lines of crops with improved N remobilization during leaf senescence will show improved nitrogen use efficiency and nitrogen harvest index, but will not overcome the imbalance between C and N acquisition caused by elevated CO2. Based on prior observations with oilseed rape, CO2 enrichment is also expected to potentially initiate vegetative growth when plants are already in the generative stage. In order to test these hypotheses, growth experiments will be performed with oilseed rape and barley under varying N and CO2 supply. N and C acquisition, remobilization and redistribution during the entire life cycle will be assessed involving 15N as tracer. Experiments will involve modified lines and wild types of recent cultivars, but also old cultivars differing in grain/seed nitrogen content und nitrogen harvest index.Keywords: senescence, nitrogen remobilization, nitrogen use efficiency, nitrogen harvest index, genotypes, atmospheric carbon dioxide enrichment.