关键词: 栓塞, 光学可视化技术, 木质部, 干旱, 维管植物

Abstract: Maintaining xylem water transport is crucial for the growth and survival of vascular plants. Air bubbles entering the xylem form cavitation embolism, impairing the plant’s normal water transportation and leading to inhibited growth or even death. Accurately measuring a plant’s embolism resistance is fundamental to understanding species traits, adaptive mechanisms, distribution ranges, and serves as an effective approach for drought risk evaluation and forecasting of forest tree species. Currently, various methods are used to quantify xylem embolism, ranging from measuring water conductivity of plant organs to direct visualization of xylem embolism. These mainly include the evaporative flux method and rehydration kinetic method for leaves, the bench dehydration, centrifugation and pneumatron method for stems, the centrifugation and pressure chamber for roots, as well as techniques applicable to different plant organs such as X-ray microtomography and optical vulnerability technique (OV) applicable to different plant organs. Among these, OV-an emerging non-invasive technique enabling in situ measurement, with minimal constraints from plant size, low equipment cost, simple construction, and high result resolution—has attracted widespread attention and been extensively applied in various plant organs over the past decade. This review first summarizes the development history, working principle, and key operational points of the OV technique. Subsequently, based on an analysis of published literature data, it synthesizes the patterns of embolism formation and spread in different plant organs, explores the differences and variation characteristics of embolism resistance across plant organs, and elaborates on advances such as the relationship between xylem embolism and decreased hydraulic conductivity, as well as the association between embolism and stomatal closure. Finally, it summarizes the technical limitations based on current research practices and provides prospects for key issues that urgently need to be addressed in the future application of this technique in plant hydraulics.

Key words: Embolism, Optical vulnerability technique, Xylem, Drought, Vascular plants