California State University Bakersfield
Welcome to the Webpage of
Dr. Anna L. Jacobsen
Plant Ecology and Evolutionary Biology
Dr. Jacobsen's Homepage Jacobsen Lab Research Page Jacobsen Lab Publications
Research within the Jacobsen laboratory examines plant structure and function with a focus on the xylem of woody plants and how plants respond to water stress and drought.
The techniques and equipment that we use are based on published methods and protocols, but because the equipment needed to conduct these measures must be custom built and is not available in total from any single source or with any single set of instruction, it is sometimes difficult for students and researchers who are trying to adopt these techniques. In the interest of assisting those who would like to incorporate these methods into their own research, we are working to post detailed descriptions of the parts, models, construction of, and use of the techniques and equipment that we use in our lab.
The hydraulic techniques, methods, and equipment that are described below have been thoroughly examined and tested. These tests have repeatedly shown that these methods produce reliable data on a wide range of species.
Please email Dr. Jacobsen (firstname.lastname@example.org) if you notice something that is unclear or incorrect in any of these files.
Plant Hydraulics Research Methods:
Single vessel air-injection
Contributed by Dr. Martin Venturas
Methods for the air-injection of single vessels to determine the air-seeding pressure distribution of vessels within samples
This file (pdf) contains a list of parts (with parts numbers) for assembling a system for measuring the air-seeding pressure of individual vessels. These data may be compiled to develop a vulnerability distribution for vessels.
Hydraulic conductivity apparatus
(posted 5/19/2011, updated 8/18/2011, updated 8/27/2014)
Methods for measuring hydraulic conductivity, xylem specific hydraulic conductivity, and leaf specific hydraulic conductivity
This file (pdf) contains a list of parts (with parts numbers) for assembling a system for measuring xylem hydraulic conductivity (Kh), as well as schematics, pictures of the system that we use in the Jacobsen lab, and additional notes about how to use the system. This file also contains details about how to measure and calculate xylem specific conductivity (Ks) and leaf specific conductivity (Kl).
(posted 5/24/2011, updated 8/27/2014)
Methods for flushing stem or root samples to measure maximum hydraulic conductivity
This file (pdf) contains detailed notes and schematics on how to construct a system to flush stem or root samples to determine maximum Kh (Khmax or Kmax), including photos of our current system and notes on how to assemble and use the system. The way that our system is currently configured, the flushing apparatus connects to the hydraulic conductivity apparatus and they both use the same captive air tank and filter. Additional notes in this file discuss some of the pros and cons to the flushing of samples prior to vulnerability to cavitation curve construction and notes on the importance of the timing of sample collection. Cavitation fatigue is also briefly discussed.
Centrifuge methods and vulnerability curve methods
(posted 5/25/2011, updated 8/31/2012)
Methods for the standard centrifuge-based construction of vulnerability to cavitation curves (measuring cavitation resistance and the water potential at 50% loss in hydraulic conductivity, P50)
This file (pdf) contains photos and schematics that describe how the centrifuge works to generate negative pressures, how to calculate pressures that are generated with the centrifuge using sample length and rpm, and some additional notes about our rotor design and modifications and how we use our system to generate vulnerability to cavitation curves. We have found that this system, as we use it, is very reliable and produces vulnerability curves that match dehydration curves, even for long vesselled species that contain open vessels through a sample.
Plant Anatomy Research Methods:
Silicon-injection vessel length distribution methods
(posted 8/19/2011; updated 8/20/2014)
Methods for determination of the vessel length distribution of stem or root samples using silicon injection
This file (pdf) contains detailed methods for using silicon-injection to determine mean vessel length and the vessel length distribution of stem or root samples.
Air-injection vessel length methods
Methods for determination of maximum vessel length using air-injection
This file (pdf) contains detailed methods for using air-injection to estimate the maximum vessel length of stem or root samples.
Active xylem staining methods
Methods for staining to determine active xylem area, sapwood area, and/or to identify hydraulically active (i.e. conductive) vessels:
This file (pdf) contains detailed methods for mixing and filtering a crystal violet dye solution and using this dye solution to stain stem or root samples in order to identify the active xylem area, sapwood area, or hydraulically active vessels found within these sections.
Measuring vessel diameter, wall thickness, and (t/b)h2
Measuring percentage vessel, fiber and parenchyma area