基于O3-FACE研究臭氧污染对有机无机肥配施下小麦氮素利用的影响

人类活动引起近地层臭氧浓度不断升高，臭氧从气孔进入作物体，破坏抗氧化系统，抑制光合过程，导致作物减产。有机无机肥配施能改善土壤肥力，提高作物氮素利用率，促进含氮光合酶和抗氧化物合成，增强作物的光合和抗氧化能力。然而臭氧对有机无机肥配施下作物氮素利用的影响及其机制尚不明确，有机无机肥配施能否缓解臭氧对作物的危害仍有待研究。本项目拟以小麦为研究对象，利用开放式臭氧熏蒸系统，设置不同臭氧和肥料处理，通过研究不同生育期小麦不同器官的氮素吸收量，探究臭氧对不同肥料处理下小麦氮素吸收及分配过程的影响；利用同位素示踪量化臭氧污染对不同肥料处理下麦田氮肥去向的影响；从叶片蒸腾、根系功能性状、土壤中氮转化相关功能微生物群落结构及氮代谢酶等方面，揭示臭氧对不同肥料处理下小麦氮素利用的影响机制。项目成果不仅有利于理解臭氧污染对农业生态系统氮循环过程的影响，也可为臭氧污染背景下制定合理的氮肥管理措施提供科学依据。

Human activities lead to elevate ground-level ozone concentration. Ozone enters the crop from the stomata, and ozone can inhibit the photosynthetic process, destroys the antioxidant system, and ultimately lead to reduced crop yields. The combined application of organic and inorganic fertilizers can improve soil fertility and increase crop nitrogen utilization. The combined application of organic and inorganic fertilizers can also promote synthesis nitrogen-containing photosynthetic enzymes and secondary metabolic antioxidants, and the photosynthetic and antioxidant capacity of crops will be enhanced. However, the effect of ozone on the nitrogen utilization of crops under the combined application of organic and inorganic fertilizers and its mechanism are still unclear, and whether the combined application of organic and inorganic fertilizers can mitigate the effects of ozone to crops is yet to be studied. In this project, wheat will be exposed to Free Air Ozone Concentration Enrichment (O3-FACE), and different ozone and fertilizer treatments are applied. The effects of ozone on the process of nitrogen uptake and allocation of wheat under different fertilizer treatments will be explored by measuring the nitrogen uptake of different organs for wheat under different growth periods. The impacts of ozone pollution on the fate of nitrogen fertilizer in wheat fields under different fertilizer treatments will be quantified through the method of isotope tracing. The effects and mechanisms of ozone on wheat nitrogen utilization under different fertilizer treatments will be revealed by measuring wheat leaf transpiration, root functional traits, functional microbial groups and nitrogen metabolic enzyme activity at different growth stages. The research results are not only important for understanding the impacts of elevated ozone concentration on the nitrogen cycle of agricultural ecosystems, but also provide scientific guidance for formulating appropriate nitrogen fertilizer management measures to improve nitrogen fertilizer use efficiency under ozone pollution.