木本植物水力学结构之导管长度研究进展

导管作为多数被子植物木质部水分运输的主要通道, 了解其结构及功能对研究被子植物水力学特性及植物对环境的适应性有着重要的作用。导管长度作为导管解剖特征之一, 对水分运输的安全性及有效性有着重要的影响。该文概述了导管长度测量及计算的方法, 导管长度在种内及种间的分布, 导管长度与导管直径的关系, 导管长度与导水率的关系及导管长度对建立栓塞脆弱曲线的影响, 并对未来导管长度的研究工作重点提出了建议: 1)改进灌注物质, 使灌注更加充分且更利于观察、提高计算精度、发展活体动态测量技术; 2)建立导管在植物不同器官及整体的分布网络以及不同生活型、不同地区的导管长度数据库; 3)对导管直径在导管方向的变化, 导管长度与其他导管特性之间的关系进行研究; 4)光学测量建立栓塞脆弱曲线技术的兴起, 可为解决离心机法建立栓塞脆弱曲线的真实与准确与否的争议提供新的方向。更深入地了解导管长度在植物水力功能中担负的角色, 可以为耐旱、抗旱品种选育提供理论基础。

Vessel length as a key hydraulic structure in woody plants: A review

Vessels are the conduit for water transport in xylem of most angiosperms. Our knowledge on their structure remains crucial in understanding the hydraulic properties of angiosperms and their adaptability to the changing environment. Vessel length is one of the major anatomical features that play a fundamental role in determining the trade-offs between safety and efficiency of long-distance water transport in xylem. This article provides a review of scholarly research on the structure and function of plant vessels, as well as the corresponding methods, measurements, scientific challenges on the influence on vulnerability curve and the relationships with other features of vessel length, as well as our knowledge gaps. Future efforts should be placed on: 1) improvement of the materials for penetration for their completion, easy-to-use, measurement accuracy, and new technology; 2) sound research on vessel network of different organs, as well as a database on vessels of different functional groups and climate zones; 3) the change in vessel diameter and other structural features with length; 4) optical measurements of xylem vulnerability for additional evidences on the roles of artificial open vessels. Advancing our knowledge on the role of vessel length in hydraulic function of plants will provide us with a theoretical foundation for improvement of drought-tolerant and drought-resistant species.