Non-invasive measurement of vulnerability to drought induced embolism by X-ray microtomography

Background/Question/Methods: Hydraulic failure induced by xylem embolism is one of the primary mechanisms of plant dieback during drought. However, many of the methods used to evaluate the vulnerability of different species to drought induced embolism are indirect and invasive, increasing the possibility that measurement artifacts may occur. We utilized x-ray computed microtomography (microCT) to directly visualize embolism formation in the xylem of living, intact plants with contrasting wood anatomy.

Results/Conclusions: These observations were compared with widely used hydraulic techniques that require destructive sampling. MicroCT imaging provided detailed spatial information regarding the dimensions and functional status of xylem conduits during dehydration. Vulnerability curves based on microCT observations of intact plants closely matched curves based on hydraulic techniques for species with short vessels or tracheids. For species with long vessels, some destructive techniques significantly overestimated vulnerability to embolism. Our results demonstrate the value of microCT as a non-invasive reference technique for determining vulnerability to embolism.