花芽分化决定着果树的产量和品质，它由植物自身和外界环境共同决定。当前，大气氮沉降已成为重要的全球性环境问题之一，作为一种特殊的“环境养分”，它将会对果树花芽分化产生何种影响，其作用机理如何，是目前经济林栽培中亟待解决的问题。本项目拟以珍稀干果树种香榧为试材，在前期已开展3年模拟氮沉降试验的基础上，从香榧根际土壤理化性质和酶活性的变化，分析氮沉降影响香榧花芽分化的土壤学机制；从花芽形态分化时间、数量、成花质量等个体水平，揭示香榧花芽分化对氮沉降的表观响应规律；从与花、果对应的茎、叶、芽中可溶性糖、总氮等营养状态变化，以及与花芽分化密切相关的GA3等激素动态、关键酶活性等林木生理水平，阐明氮沉降影响香榧花芽分化的生理调控机理。研究成果可为全球环境变化背景下科学认识氮沉降的生物学效应，调整经济林经营管理策略，保障我国经济林产业健康发展提供新思路，具有重要的理论和实践意义。

Floral transition is an important trait, which is associated with nut tree production. The number and quality of floral transition are determined by both plant itself and environment. However, atmospheric nitrogen (N) deposition serves as an environmental nutrition, and its effects on plant phenology (i.e., floral transition) has often been overlooked. As N deposition is predicted to be increasing in the future, China is facing the challenge to update the traditional strategies of forest and agriculture management. However, how N deposition affects plant phenology remains unclear. Here, Torreya grandis, an important nut tree species is selected for this study. We aim to evaluate the key stage of resource availability that determines floral initiation and demonstrate the mechanism of N deposition effects on flowering. We investigate soil nutrition and the epigenetic and physical responses of T. grandis trees under different doses of stimulated N deposition. Results will not only provide novel data for understanding the physiological machinery that how the increasing N deposition may influence flowering of nut trees, but also provide insights into the improvement of production and management strategies under the background of climate change.