Comparison of methods for detecting vulnerability of xylem embolism in Robinia pseudoacacia

Abstract

Aims The vulnerability of xylem embolism is one of the key physiological factors that are related to plant mortality. Vulnerability curves are typically used for determining the vulnerability of xylem embolism. However, the shapes of vulnerability curves vary with the methods of assessment, especially in plant species with long xylem vessels. This study aims to investigate the feasibility of using different methods for establishment of vulnerability curves. Methods Robinia pseudoacacia branches, with long xylem vessels, were used as plant materials for comparison of three different methods in establishing vulnerability curves, including bench top dehydration, Cochard Cavitron centrifugation and Sperry centrifugation. In the Sperry centrifugation method, rotors of two different sizes were used to test the ‘open vessel artifact’ hypothesis. Important findings The vulnerability curve established by the bench top dehydration method displayed an “s” shape, while both the Cochard Cavitron centrifugation and Sperry centrifugation methods produced “r” shape curves. Vulnerability curves derived from the bench top dehydration method and the centrifugation methods were significantly different. Using the Sperry centrifugation method, the R. pseudoacacia branch samples in the 14.4 cm rotor had a higher proportion of open vessels, while the embolic vulnerability curves established on the 27.4 cm and 14.4 cm long stem segments were similar, indicating that the Sperry centrifugation method does not produce “open vessel artifact”.