木质部水分传导的有效性与安全性是两个具有相对意义的性状。在湿润环境中，水分传导的安全性由外界保障，有效性是植物发挥竞争优势的有力手段；而在干旱环境中，水资源不足，植物为了维持生命，安全性就显得更加重要。因此，木质部水分传导的有效性和安全性是我们理解植物适应干湿不同环境、增加适合度的重要基础，是值得关注的重大理论和现实问题。本项目拟以沿降水梯度自然分布的9种锦鸡儿属植物为研究对象，分析植物茎、叶水力传导结构的分化特点，揭示以水力传导结构分化为基础的茎、叶水分传导有效性和安全性的分化与权衡关系，确认叶水分传导安全性对锦鸡儿属植物沿降水梯度形成替代分布的决定性作用，从而深入认识不同降水量分布区锦鸡儿属植物对水分环境变化的水分传导适应机制，丰富植物抗旱性形成的理论体系。

Plant water-conduction systems are an important component of plant tolerance to drought, with hydraulic efficiency and hydraulic safety being the most important functional properties. In humid environemnt, plants sedomly experence water stress, and it is important for plants to increase hydraulic efficiency to improve their competition capacity for light and nutrients, while in arid environment, it is important for plants to increase their hydraulic safety so as to maintain their survival under severe water stress. Therefore, hydraulic efficiency and hydrqulic safety are the foundation for us to understand the performance of plants from different environments. This project will use 9 Caragana species from larger-scale precipitation gradients as materials to investigate: difference in stem and leaf anatomy and differentiation law of hydraulic architecture along precipitation gradients; whether resistance to cavitation is negatively associated with hydraulic conductivity, reflecting a trade-off between hydraulic efficienty and hydraulic safety; and the influence of hydraulic safety of stem and leave on the distribution of substitute species of genus Caragana. The project proposal will not only aid in revealing hydraulic conductivity traits in Caragana species from different precipitation, but also providing a deep insight into mechanisms of plants to adapt to drought stress.