Lemna lab problems

Christopher T. Cole colect at mrs.umn.edu
Tue Nov 7 12:57:37 EST 2000

I've grown a lot of Lemna & can't answer your question but can tell you
what to look for.  Fluorescent lights are fine, even very close to the
plants.   The bleaching could be photobleaching, maybe, but that usually
takes a sudden shift to very high light levels, and the plants recover
quickly.  Chemical bleaching is more likely. This could come from a drastic
drop in pH, and the strength of the acid is more important than the pH per
se (i.e. Lemna can handle fairly low pH if the acid is weak).  Another
possibility is something that poisoned the chloroplasts, such as
antibiotics or herbicides.  The fertilizer you use should be dilute, e.g.
1/4 X Hoaglunds max.  Are you confident about your water quality &
fertilizers?  Any changes in these that might have killed the Lemna?

Duckweed is stubborn, yes, but not obstinate.  It likes to grow and will do
so for you given the least chance.

Best of luck.

-Chris Cole

At 03:55 PM 11/7/00 +0000, Eric Ribbens wrote:
>We're trying a new lab here, population growth using Lemna minor. We've 
>been cultivating it in the greenhouse (it turns out for 22 + years!), but 
>when we set up the growth experiment the thalli promptly all bleached white 
>(within two days). The ones left in the dark are the only ones which didn't 
>bleach, although they are looking a bit poorly as well. Any idea why? 
>Fluorescent light? Increase in light intensity? Water chemistry change? 
>Just general stubbornness?
Christopher T. Cole
Associate Professor of Biology
University of Minnesota - Morris
Morris, MN
colect at mrs.umn.edu


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