plant physiology

Virginia Berg Virginia.Berg at uni.edu
Wed Nov 29 09:56:56 EST 2000


I don't have anything worked up (or in process), but if I had to come up
with something fast, I'd use seed germination.  If you have any way to
control temperature (a cold wall vs the room vs near lights), you could test
different kinds of garden seeds (peas vs beans vs squash, for example).
Different soil moistures (by weight), different soil types (extremes),
fertilizer (or not) and germination inhibitors (commercial?) would all work
(giving different answers or not).  Furthermore, you could get some Fast
Plant seeds and test for the effect of light on germination (using garden
seeds, too) and (for garden seeds) on early growth and development.  Most of
the trials lend themselves to simple counting (with some weighing and
measuring), and the "ingredients" are cheap.  I would not worry about having
things too simple. People who do photographic printing have lots of
light-tight bags to give away.  Film cans (especially the really clear ones
that show the roots--from Magic Color in the US) can be gotten for nothing,
but need frequent watering, perhaps throught a wick system like the
Wisconsin Fast Plants.  My best results in 1-week trials with film cans have
been with pre-moistened fake soil and telling the students NOT TO WATER
until the soil is dry.  They put the film can caps on off-center to retard
evaporation from the soil. Tropisms (including color effects) can also be
done using the "sprouts."  

An experiment I've always wanted to do with kids: Drag out of the kids the
idea (maybe they have to see some plants first) that the cotyledons of beans
might provide stored food for the plant, and also do photosynthesis.  Then
get them to come up with the following experiments:  Cut the distal quarter
(half, three-quarters) of the cotyledons off and see what the effect on
growth is.  Is the effect of removing one whole cotyledon the same as the
effect as removing half of both (i.e. is the food fully redistributed)?
Does it matter when the cotyledons are removed? You would profit by imbibing
the seeds in very moist (but well aerated) soil for a day first.  Are the
results of cotyledon removal the same in the dark as in the light?  How much
difference does it make if we cover the cotyledons (one or both) with foil
to block photosynthesis? Which counts more, stored food from the cotyledons
or photosynthesis from the new leaves?  Although these seem really simple, I
don't know how they would come out.  Thinking of it, I might use this
instead of the more elaborate version above.

--Gini Berg


Today three billion people will eat rice. 
The genome is being sequenced. 

Virginia Berg  (bergv at uni.edu)
Biology Department 0421
University of Northern Iowa
Cedar Falls, IA 50614
(319) 273-2770 (phone), 273-2893 (fax)
http://www.uni.edu/berg


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