Estimation for Embolism Risk of Tomato Using Acoustic Emission Response to Increased Drought Stress

抄録

Acoustic emission (AE) occurs in the xylem during cavitation. In fact, AE behavior is influenced by changes in drought stress. For this study, four AE sensors were attached to a miniature tomato plants to investigate AE behavior during a long-term (32 d) change of drought stress. The change ratio of the AE occurrence rate from nighttime to daytime, R_DAE roughly corresponded to the soil moisture when the soil moisture was less than 20% (VMC) though only one sample was used for the long-term measurement. Then, AE behavior occurring concomitantly with a rapid change of drought stress, induced by stem cutting, was investigated. The change ratio of AE occurrence rate caused by stem cutting corresponded to the drought stress, which was influenced by the cutting timing and soil moisture. The experimental results were explained using the model in which severe drought stress induced a transition of the embolism from temporary to permanent status. A parameter incorporating the change ratio of the AE occurrence rate caused by stem cutting well indicated the degree of embolism risk.