Lee, David .
Plastic soda bottles as shade enclosures to study seedling development.
The discovery that phytochrome mediates plant responses to shifts in spectral quality has stimulated research on the spectral and intensity components of shadelight in controlling plant development. It is educationally and scientifically valuable to develop a simple experimental apparatus for providing shading that manipulates both intensity and spectral quality to determine the effects of each component on plant development. This is of sufficient interest and accessibility for use by high school and college students. Also, since this shade-detecting mechanism is the plantís means of detecting crowding by its neighbors, this might be explained to younger students in a way that is appealing to them. Here I describe the cutting of 2 liter soda bottles into shade enclosures, and 1 gallon plastic milk bottles as the growing pot and enclosure receptacle. Phytochromes a and b have a maximum sensitive to red (660 nm) and far-red (730 nm) wavelengths, and the red:far-red quantum ratio varies from 1.05-1.25 in sunlight (increasing with humidity) and 0.25 in deep forest shade to affect the Pr and Pfr equilibrium. A neutral shade film (3M, #RE20) does not change the R:FR of sunlight, but reduces the intensity of photosynthetically active radiation (PAR) to 0.19. A dye-impregnated film (3M, #FXST20) reduces solar PAR to 0.19 and 1.25 R:FR to 0.25. These enclosures can be used to demonstrate the additional effects of low R:FR on plant development, or additional shading (gray plastic screening) reduce shading an additional 0.40 to provide the conditions for a factorial design and 2-way ANOVA for advanced students. Sample results will be demonstrated with chick pea and Wisconsin fast plants.
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1 - Florida International University, Dept. of Biological Sciences, 11200 SW 8th St., Miami, FL, 33199, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Superior A/Cliff Lodge - Level C
Date: Tuesday, July 28th, 2009
Time: 9:30 AM