photosynthesis lab

Robert C. Hodson hodson at UDel.Edu
Mon Mar 13 10:47:36 EST 2000

We can not say enough good things about the Qubit Systems Inc.
photosynthesis equipment.  We have twenty of the Advanced PS packages,
each connected to a laptop computer.  The apparatus has a high "fiddle
factor" (words of another customer via Steve Hunt).  Of course a sizeable
source of funding is required, but if available it is a very good use of
financial resources.  Variables include light intensity (with no
precautions for overheating needed), CO2 concentration, plant species (C3,
C4), and more.  We modified the open flow-through system (CO2
concentration monitored by absorption of infra-red light) to be closed,
and determined the CO2 compensation points for soybean (C4) and corn (C3)
which agreed fairly well with published values.  We also used the same
setup for determining dark respiration rate.  If one uses a leaf large
enough to fill the cuvette area and thereby serve as a gasket separating
the upper and lower cuvette chambers, one can determine the relative
contribution of upper and lower leaf surfaces (related to number of
stomata).  By monitoring relative humidity one can get an estimate of
stomatal opening, which tracks very nicely with PS in plants kept a few
hours in darkness or dim light before experimentation.  I am happy to
serve as a consumer-consultant for anyone contemplating purchase of the

Robert C. Hodson
Department of Biological Sciences
University of Delaware
Newark, DE 19716

On 13 Mar 2000, Beverly Brown wrote:

> Does anyone have a photosynthesis lab of which they are particularly
> proud?  We have two labs, one for non-majors and one for majors.  They
> include variations on watching spinach disks rise in varying light
> intensities, varying wavelength intensities, and the old Coleus leaf,
> boiled, with iodine, etc.  This series of experiments is prone to great
> failure and we would like to revamp it entirely!
> Thanks!
> Beverlyl
> --
> _:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:
> Beverly J. Brown, Ph.D.                Phone:  716-389-2555
> Nazareth College of Rochester       Fax:      716-586-2452
> Biology Department                      E-mail: bjbrown at
> 4245 East Avenue
> Rochester, NY 14618-3790
> _:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:_:
> ---


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