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steam girdling

Robinson, Dr. David drobinson at BELLARMINE.EDU
Thu Jun 11 15:12:12 EST 1998

Jon Greenberg:   Maybe you should deliver the girdling heat via tubing.

Set a hot water bath to the desired temperature, pump water though
rubber tubing and then run the rubber tubing into a short piece of metal
tubing. The metal conducts heat more efficiently than rubber so the
plant can be clamped between two of these hot metal tubes and voila.
This heat treatment is very localized. We did some experiments at warm
temperatures (like 52C) with this apparatus but we could have cranked it
up to scalding I suppose. 

I have an article on this in Crop Science (1990; vol 30, page 138). We
provide a description and photo of the apparatus in that article.

Dave Robinson
Biology Dept
Bellarmine College
Louisville, KY

	-----Original Message-----
	From:	koning at ecsuc.ctstateu.edu
[SMTP:koning at ecsuc.ctstateu.edu]
	Sent:	Wednesday, June 10, 1998 9:48 PM
	To:	plant-ed at net.bio.net
	Subject:	Re: steam girdling

	At 3:36 PM -0400 6/9/98, Jon Greenberg wrote:
	>Has anyone had experience with steam girdling to kill phloem
	>mechanically injuring a plant stem? I'm working on a high
school biology
	>text and would like to include an activity to stress the
	>between transport in dead xylem vesels and live phloem.
	>I'm picturing a 250 mL flask of boiling water with a one-hole
	>and a piece of wide rubber tubing slit lengthwise near the end
to insert
	>the stem and close with a pinchcock or screwcock clamp. But
will this
	>work? Will the steam cool and condense too much before reaching
	>stem? Or will it jet out and scald the kids? Any thoughts or
hints for
	>this experiment?

	Carol Reiss has something on this in her excellent lab
	exercises book.  I don't have it here just now, but
	think more along the line of putting a glass tube in
	the end of the flexible tubing to direct the steam.  You
	just point the end of the tube and hit the localized
	spot on the stem you wish to treat with the steam coming
	out of the tubing.  You definitely DONT want to clamp
	off the tubing on a flask of boiling water...that would be
	a severe safety hazard!  You don't need much steam and a
	slow boil in the flask is all that is necessary to achieve
	the results.

	You are correct that live steam is a scalding hazard and
	precautions are wise...a heavy plastic apron, gloves, and
	the use of water-impermeable insulation on the tubing.
	Goggles and Pyrex are important too.


	Ross Koning                 | koning at ecsu.ctstateu.edu
	Biology Department          | http://koning.ecsu.ctstateu.edu/
	Eastern CT State University | phone: 860-465-5327
	Willimantic, CT 06226 USA   | fax: 860-465-4479

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