Subject: Re: measuring stomatal frequency, depth, etc.
From: [email-masked] (Pedro J. Aphalo)
Date: Mon, 25 Jul 94 06:54:07 GMT
Newsgroups: bionet.plants

In article <[email-masked]>, [email-masked] (Ellen 
V Kearns) says:
>
>
>Howdi,
>
>In response to Frank Berninger's request for information about how to 
model 
>the diffusion process for birch leaves, stomatal frequency can be 
measured
>by looking at epidermal peels under microscope magnification of about 
200X.
>
>The open width can also be measured by microscopy with a special eye 
piece
>which has an etched ruler on it. As for depth of cavity, I have seen 
pictures
>of this in a review, but I am not sure how to measure it. 
>
>I'll send some refs. about these measurements on Monday. Sounds like an
>interesting project!
>
>Ellen Kearns
>[email-masked]  

A caveat:
What you say is true only if you do not want to validate the model or
estimate gs under a given environmental condition because using epidermal
peels does not allow one to measure the stomatal dimensions as they
were in the leaf before peeling. If one floats the peels in an adequate
medium and light conditions one might be able to measure the dimensions
under maximum aperture. Of course, peels (or cyanoacrylate cement, 
Loctite, replicas) are very good for measuring frequency and density.
The Loctite replicas may be good enough for measuring stomatal
pore width, but that would have to be validated with a method known
to work, such as using SEM on frozen samples.

This is why I suggested the use of SEM in my previuos posting to 
bionet.plants. Peels or even whole leaves measured using light 
microscopy normally do not yield measurements that reflect the in 
planta stomatal aperture before disturbance (see Weyers and Meidner1990).

I agree that Frank's project is very interesting, but as with any model,
he will need to validate the estimates against actual gs measurements
made simultaneously with measurements of stomatal dimensions.

Pedro.

=======================================================================
 Pedro J. Aphalo
 FINNISH FOREST RESEARCH INSTITUTE
 FIN-77600 Suonenjoki
 Internet: [email-masked]
 fax: +358 79 513 068                                   ,,,^..^,,,
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