Research progress on the methods for measuring xylem embolism vulnerability

Abstract

Changes in the frequency and severity of drought events associated with climate change could affect plant growth, development, and adaptability. Hydraulic failure caused by xylem embo-lism is the main physiological consequences of drought stress. How to accurately quantify xylem embolism is particularly important for understanding plant responses to drought stress. The vulnerability of xylem to embolism is usually evaluated by constructing vulnerability curves (VCs). Several methods have been developed to construct VCs, but be inconsistent in their results. A deep understanding of the design principles of xylem embolism measurement methods and comparison of the similarities and differences of various methods in actual research are particularly important for the rational interpretation of literature results, and properly using VCs in models for predicting plant responses to water deficits. Here, we compared seven methods for constructing xylem vulnerability curves to embolism: bench dehydration, centrifugation, air injection, acoustic measurements, synchrotron and X-ray microtomography (Micro-CT), optical visualization method, and pneumatron method. We summarized current achievements and controversial viewpoints of the application of these methods in specific research. Finally, we provided prospects for measuring the vulnerability of xylem embolism and the selection of relevant methods for practical application in future studies.