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Many years back we ran a plant in a box exhibit with simple sensors to track photosyhthetic activity and parameters, and was able to get a number of variables to react very quickly, a minute of less ( not a light dark transission, but response to light). we tracked o2,co2, and water vapour ( relative humidity) as a measure of transpiration.
Basic rule we found was not suprising, the faster we got the plant to respond, the more we stressed it.
But we were able to have it run for several days between swapping in fresh plants
The key to getting quick responses was to keep the surrounding air volumes small compared to the plant volume (leaf area), i.e. small box big leaves. We used a low speed. low volume fan system to draw air through the box, and picked up the gases in the exhaust air. Important to have a heat absorbing glass filter between the plant and the light source as thermal stress will over ride normal metabolism.
we had success with young english spinach, peas, beans, and sunflowers. young activly growing plants have more metabolically active tissue, and are likly to give you the clearest transitions.
best of luck
Stuart Kohlhagen
Manager New Concepts
Questacon
Classification: UNCLASSIFIED
________________________________
From: Informal Science Education Network on behalf of Charles Carlson
Sent: Sat 4/08/2007 1:27 AM
To: [log in to unmask]
Subject: Re: Plant Respiration Activity.
ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
*****************************************************************************
Tim,
The carbon dioxide sensor will work, but the oxygen sensor will
always be way too slow for your needs. It's the ways of physical
chemistry. You'll see it in the spec sheets if you compare them.
C
On Aug 3, 2007, at 7:56 AM, Tim Pula wrote:
> Vernier data collection sensors
Charles Carlson
Director of Life Sciences
exploratorium
3601 Lyon St.
San Francisco, CA 94123
[log in to unmask]
Tel: 415-561-0319
Fax: 415-561-0370
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