UV Radiation and Plants
A Paper by Ethan Stricker-Chapman
A number of deformed frogs were found in northern Minnesota. Through experiments, it was shown that these deformities, which included loss of limbs and an abundance of limbs, are probable attributed to UV radiation.
UV light has been divided into 3 main groups: UV-A(320-400nm), UV-B(280-320nm), and UV-C(<280nm). UV-C is absorbed by the ozone, and UV-A does not pose a biological threat, do UV-B is all we have to worry about.
The black light was a Sylvania F15T8 bulb, with 15 watts, and 18-inch MOL, and 7500 hours of life. The wavelength is 356 nm, in the UV-A range, however, since UV-B is more harmful than UV-A, the results should provide a sound basis for extrapolation.
The experiment lasted from March 21 to April 12, 1998. It took place in southeastern Minnesota (Crystal), with eastern exposure. The light was propped up on two wooden blocks, each an inch thick. The cress sprouted on March 28. There was no visible difference at the time of sprouting, because I delayed the use of the black light until the plants had sprouted. In the beginning, I had the black light on 24 hours a day, but on March 30, I decided to turn it on at sunrise and turn it off at sunset, in order to more effectively model the real conditions. Earlier, I had tried the same experiment with beans, but the growth was more controllable with rock cress, so I decided to switch. Also, on March 30, I decided to take one of the lights out, because there was far too much UV light and far too little sunlight. After only about a day, the UV light was producing visible effects, such as slower growth and difference in color. Most of the UV plants had died by the end of two weeks, and remain dead (see leaves). An interesting thing was that the blocks had stopped the UV light from reaching some of the plants, and those plants all survived. At the end of my experiment, I also looked at a control and a UV leaf. The control's leaf was 0.8 cm at its longest, and the UV's was 1.4 cm (see growth record).
Results and Conclusions
Given the results of my experiment, I feel I can safely say that if you were a rock cress in southeastern Minnesota in March with a steady dose of UV light, you'd probably be dead.