At 10:08 AM 10/20/95 -0700, Mike Snow wrote:
> If I understood the experiment correctly, the seeds were
>germinated directly in fruit juice. Do lettuce seeds float on fruit
>juice? If not, the level of available oxygen surely seems a potential limiting
>factor
Michael,
The Petri dish is 10 cm diameter with a disc of 9 cm filter paper.
The volume of solution is 5 mL which is just enough to moisten the
paper. The seeds are thus in a very thin film on top of the paper.
The seeds in the same volume of plain water do not have a problem
with this. The tomato juice *is* more viscous than water and might
present a more difficult path for oxygen, but the film is so thin
that I doubt it is much of a problem. I don't know how sensitive
lettuce seed is to anoxia, but we keep the volume this low just to
avoid the problem. Some seeds are incredibly sensitive to anoxia
and some will germinate ONLY in semi-anoxia (eg. rice).
You are correct, though, that this is another variable a student
could pursue in an independent project. The volume of liquid could
be increased among several trials to test it. I'd use water though
since, so far, we have had NO germination even in our thin films
of tomato juice.
ross
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\ Ross Koning \
\ Biology Department \
\ Eastern CT State University \
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