ecophys labs

Bill Williams WEWilliams at
Mon Feb 5 12:57:27 EST 2001

>I am teaching a course on plant ecology this semester and would welcome
>suggestions for lab exercises, particularly on water relations (using a
>pressure chamber) and photosynthesis (using an IRGA).   Thanks.
>Scott Shumway


We often begin our plant-physiology course labs with a survey of the 
differences between shade- and sun-grown sunflowers. (We just grow 
the sun-grown on top of a greenhouse bench and the shade-grown on the 
floor underneath the same bench.) They show very obvious differences 
in overall morphology, chl a:b ratios, and photosynthetic light 
curves (we've been using O2 electrodes, but an IRGA would be at least 
as good -- what are you using?). Water relations are a bit trickier 
because, as you undoubtedly know,it's very difficult to water-stress 
a plant growing in a small pot without killing it. We sometimes see 
pretty clear differences between noon and pre-dawn water potentials 
in the sun-grown sunflowers, though; you might try that.


William E. Williams
Biology Department
Saint Mary's College of Maryland
18952 E. Fisher Rd.
Saint Mary's City, MD  20686-3001


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