John Sperry’s account of the history of the double-ended pressure chamber, specifically as it relates to inducing cavitation and measuring vulnerability curves
Background papers showing cavitation by air-entry:
The first paper I know of implicating air-entry at pit membranes as the cause of cavitation is 1985: Crombie, Hipkins & Milburn 1985. Gas penetration of pit membranes in the xylem of Rhododendron as the cause of acoustically detectable sap cavitation. Australian Journal of Plant Physiology. 12:445-453.
The first PLC-type vulnerability curve using negative sap pressure was published in 1986: Sperry, J.S. 1986. Relationship of xylem embolism to xylem pressure potential, stomatal closure, and shoot morphology in the palm Rhapis excelsa. Plant Physiology. 80:110-116. I developed the PLC method as part of my PhD thesis. Interestingly, I also did an air-injection vulnerability curve back in the early 1980’s…it matched the negative pressure one so well that I didn’t believe it and so never published it!
In 1988, myself and Mel Tyree added more evidence that air-injection could be used to estimate vulnerability; by measuring rates of air flow through stems longer than the longest conduits. Sperry, J.S., M.T. Tyree. 1988. Mechanism of water-stress induced xylem embolism. Plant Physiology. 88:581-587.
Four key papers on using pressure chambers to induce cavitation and obtain PLC-type vulnerability curves.
1. The first PLC-type vulnerability curves using air-injection and a single-ended pressure chamber were published in 1990: Sperry, J.S., M.T. Tyree. 1990. Water-stress-induced xylem embolism in three species of conifers. Plant Cell and Environment. 13:427-436. In these experiments, air was injected into one end of a stem that was much longer than the xylem conduits, and the percentage loss of conductivity (PLC) measured on a segment of the stem distal to the open conduits at the injection end. Many stems had to be injected to compile the complete vulnerability curve (one stem = one data point).
2. In 1992, Cochard and colleages (Cochard, Cruziat, and Tyree (1992) Use of positive pressures to establish vulnerability curves. Plant Physiology 100:205-209) did complete vulnerability curves on single stems that were flexible enough to bend in a “U” shape and insert into a single-ended pressure chamber. Like the double-ended version, this allowed PLC to be measured on a single stem as air pressure was increased, thus getting the whole curve from one stem.
3. Also in 1992 the first double-ended pressure chamber was built by Salleo and colleagues (Salleo, Hinckley, Kikuta, LoGullo, Weilbony, Yoon, Richter 1992. A method for inducing xylem emboli in situ: experiments with a field grown tree: a technical report. Plant Cell Environment 15: 491-497.) According to co-author Tom Hinckley, it was Hanno Richter’s idea. As the title indicates, the intent of the double-ended bomb was to put it on intact trees and induce embolism and study the effects. Hence it was a split design. It was not used to do vulnerability curves.
4. In 1994, we published the first paper that specifically used a non-split, double-ended chamber designed to measure vulnerability curves on single stems by air-injection. (Sperry, J.S., Saliendra, N.Z. 1994. Intra- and inter-plant variation in xylem cavitation in Betula occidentalis Plant Cell and Environment. 17:1233-1241.) We included chamber plans, and a detailed measurement protocol, with tests on air-injection times, effects of notching, solution used, and so forth. It is from this particular paper that the use of your PMS bomb most directly developed from. We used to informally call our double-ended bombs “Richter-constricters” in honor of Hanno Richter’s idea, although many folks, including ourselves, were thinking along the same lines by that time.
And the rest is history…
Since then, we and others (PMS and other individual labs) have made many double-ended bombs, of different sizes, some split, others not, for a variety of purposes related to embolism studies. Similarly a variety of single-ended or “clamp-on” injectors have been built. Many publications, of course, have resulted. But I believe it was these four initial publications that got the ball rolling.
Contributed to PMS Instrument Company on April 8, 2010 by John S. Sperry via email.