colored light filters

Ross Koning Koning at ECSUC.CTSTATEU.EDU
Fri Oct 6 16:49:11 EST 1995


Here is what works for me:

I bought some colored plexiglas at a local plastics
supply company.  It comes in various thicknesses and
color densities.  I bought intense red and blue.  I
mounted these on some wood frames to contain Petri
dishes with lettuce seeds.  The Agway 'Salad Bowl'
seeds responded as anyone would predict using these
filters.  Red germination was 85%+, Dark (wrapped in
foil) was about 20%, and Far-red germination was 0%.
The far-red treated seeds, after being brought into
white light, germinated to about 70%.  I use fluorescent
light over the red filter for red, and incandescent
lamp over the red+blue filter for far-red.  I have
not attempted to measure photon flux under either
set-up, but should some day.  It has been simple and
it works.  Plexiglas is easy to work with because
you can use common saws and drills with it.  My
sheets are simply screwed to the wood frames...no
rabbet nor dado in the frame!

Good Luck!

ross

At  1:10 PM 10/6/95 -0700, bio_jxn at shsu.edu wrote:
>Does anyone have a name, address, phone number of a source of light filters
>for experiments in a plant physiology lab?  I "inherited" small glass filters
>but would like to set up an experiment in a large box with one side removed
>and replaced with a large piece of filter of glass or "cellophane" type
>material.  The plastics person assured me his filters were not really
>filters but just tinted plastic and would allow all wavelengths
>to be transmitted.  I would like to be selective for red, blue and green.
>
>Thank you in advance and thanks also to all who responded to the tissue
>culture question several weeks ago.  The "plant-ed, net" is
>especially useful when teaching a new class with an extensive laboratory.
>When extra time is scarce, this mode of inquiry/communication is
>invaluable.
>
>Joan Hudson
>Dept. of Biological Sciences
>Sam Houston State University
>Huntsville, TX

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