What is the fastest-growing plant? Measuring growth.

Kevin Blaze klb at bbs.ausom.oz.au
Wed Feb 2 04:30:08 EST 1994

I want to use an LVDT to demonstrate the effect of light on plant growth. I am currently developing the necessary apparatus but need suitable material for the demonstration: a plant that grows very rapidly.

If you have never used one of these devices, please keep reading because you may still be able to help me with information on plant material.

For those who donUt know, an LVDT is an electronic device that looks something like a syringe. As the plunger moves into the syringe, the electrical output changes proportionally. Unlike the syringe, the movement is almost frictionless. The system will al

The aim of the exercise is to make a demonstrable connection between light and plant growth. Ideally, I will be able to turn on the light and observe elongation of the leaf within a few minutes. The elongation should cease when the light is turned off. Th

The opening of the stomata (when the light is turned on) will cause an increase in transpiration, reducing the turgor of the cells so that they probably will not grow. When the lights are turned off, the stomata will close, turgor will be restored and the

It is my presumption that if I:
1. maintain the transpirational requirements (perhaps by growing the plant hydroponically),
2. keep these transpirational requirements low (by using low light intensities), and
3. use a plant that grows very fast,
I should be able to demonstrate the connection between light and growth.

Now, I know it would be nice to go into the effect of turgor on cell extension (as IUve explained above) but itUs for TV and there simply is not the time to go into it at that depth. The bottom line is: if I canUt demonstrate it directly, we wonUt do this

The region of growth must be below the point of attachment of the thread from the LVDT so that the thread will rise as the leaf/plant grows.

A grass would allow me to attach the thread from the LVDT near the top of the leaf without affecting the meristem (which is basal).

Another possibility might be to use a herbaceous or woody plant that has rapid internodal growth; I could then attach the thread to the top of the plant.

I need a plant that is either native to my part of Australia or is commonly used in horticulture (which will therefore include many foreign taxa). Please remember that it is summer here (in case that is significant).

If possible, please give me botanical and common names and indicate growth rates and the necessary conditions.

If youUve carried out this exercise (or something similar) or know of a paper describing a suitable method, please let me know. By the way, I know the method can be used for assessing water stress.

Due to problems with regularity of newsfeeds or disk space (or some other technical reason), old news from the newsgroup is discarded every two or three days so that unless I download every couple of days, I miss news! So, please can you send me a private

With thanks in anticipation.

Kevin L. Blaze
Victorian College of Agriculture & Horticulture (Burnley)
Burnley Gardens
Swan St
Australia 3121
Tel.: Int + 61 3 810 8800
Fax: Int + 61 3 819 1383
e-mail: klb at ausom.oz.au

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