Speaking of Kalanchoe...

David Hershey dh321 at excite.com
Thu Feb 10 23:12:07 EST 2000


Friend (1990) titrated the acid in Kalanchoe daigremontiana leaves to
demonstrate CAM. 

K. daigremontiana is also an excellent teaching plant for a wide variety
of uses. It works well in hydroponics. I have grown plantlets in
unaerated nutrient solution in 35-mm film cans to demonstrate mineral
nutrient deficiencies. 

It is a LD-SD plant for flowering but a LD plant for plantlet formation
on the attached leaves. Detached leaves appear day-neutral for plantlet
formation. The LD requirement for flowering can be overcome with a
gibberellic acid application.

Detached leaves placed in constant darkness dehydrate much more rapidly
that those kept in constant light. The plants grow well under the
flourescent light banks used for Wisconsin fast plants. 

References:

Friend, Douglas J. C. 1990. How to Do It. Plant Eco-Physiology:
Experiments on Crassulacean Acid Metabolism, Using Minimal Equipment.
American Biology Teacher. 52:358-63. (Sept. 1990)

Hibbs, E. Thomas and Yokum, Nanci G. 1976. Bryophyllum: A Versatile
Plant for the Laboratory. American Biology Teacher. 38:281-283. (May
1976)



David Hershey

---------

Jon Greenberg wrote:
> 
> Speaking of CAM plants, does anyone have an activity for demonstrating
> some aspect of this pathway or distinguishing it from C4, in a way that
> is suitable for high school students? (14C tracers, for example, are
> out.)
> 
> I thought, for example, that it might be possible to titrate, or just
> compare the pH of crude leaf extract at (simulated) dawn and dusk to get
> at the idea of a diurnal cycle of C4 acid accumulation.
> 
> Many thanks for any ideas.
> 
> Jon Greenberg
> BSCS
> 
> ---




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