Bassica Rapa vs. Acid Rain

INTRODUCTION

Acid rain has been a major concern of ecologists around the world. Acid rain is rain that has been mixed with sulfur dioxide and nitrogen oxides that come from the combustion of fossil fuels. It has been called the single most important environmental threat to the United States and Canada. It has very powerful destructive capabilities and can ruin crops. Acid rain has rendered 212 lakes in the Adirondacks unfit for fish. It threatens nearly 150 miles of West Virginia's total 550 miles of native brook trout streams.

Acid Rain is said to have a devastating effect on the forests of the world. This hypothesis has never been proven. Many scientists, such as Professor Ulrich of the Institute of Soil Science and Forest Nutrition at the University of Gottingen in Germany and Dr. Arthur H. Johnson of the University of Pennsylvania, have argued that there is no scientific proof that acid rain has had a significant effect on the forests of the world. There is also no scientific proof that acid rain has not had an effect on the forests.

The purpose of this project was to observe how different pH levels of water affected the growth of Brassica Rapa rosette plants. The water was made to simulate Acid Rain in both strength and chemical make-up. Acid rain is a very serious problem and it needs to be known how different levels of acidity in acid rain affect plant growth.

There have been many tests on plants to see how they react to different pH levels of soil. In Norway, researchers exposed lodgepole pine, Norway spruce, silver birch, and Scots pine trees to acid having pH levels ranging from 2.0 to 6.0. After seven years, the conclusion was that the acid had no effect on the growth of the trees. Tests on the effects of acid rain on trees have had varying results. The effects have ranged from positive to negative with some results showing no effects at all.

Another test on the effects of acid rain on plants was performed by a CVGS student named Kisha Perkins in 1993. She used pH levels of 4.0, 5.6, and 7.0. She determined that Brassica Rapa plants in the Eastern United States normally grow at a pH of 5.6. Her results showed that lower pH levels of nitric and sulfuric acid stimulated plant growth for a little while and then killed the plants.

Brassica Rapa plants have a very short lifespan (30 days) and because of this, they are very good test subjects. The roots of the plant begin to appear at day 1. True leaves develop by day 5. With the fast growth of the plants, scientific studies can be performed in a shorter period of time.

MATERIALS AND METHODS

Brassica Rapa rosette seeds were obtained from the Carolina Biological Supply Company. They were grown according to the steps outlined in the Wisconsin Fast Plants Growing Instructions. The seeds were chosen for this experiment because of their very short lifespan. The seeds were then placed in four groups of eight seeds each. These groups consisted of three experimental groups and a control group. The bottoms were cut out of four three liter drink bottles. Eight quads were obtained to plant the seeds in. Wicks were placed in the bottom of each quad in order to provide a way for the plants to water themselves. Hoffman's Fertilmix Potting Soil and Seed Starter was then placed halfway up each section of the quads. Three fertilizer pellets were then placed in each section. Soil was then added to cover the pellets and the seeds were placed in the sections. The sections were then filled the rest of the way with soil and watered.

Stock solutions of Sulfuric acid were prepared at pH levels of 3.5, 4.5, and 5.6. The solutions were poured into the bottoms of the bottles. The control group was given a solution with a pH of 5.6 to simulate natural growing conditions. The first experimental group was given distilled water having a pH of 7.0. The second group had a solution with a pH of 4.5 to simulate natural acid rain. The third experimental group was given a solution with a pH of 3.5 to simulate a lower pH of acid rain. Long strings were threaded through another bottom of a drink bottle and the second bottom was placed upside down in the first bottom of the bottle. A mat was placed on the top of the second bottle. The quads were then placed on the mat. Two quads were used for each group. The tops were then replaced on the bottles to keep moisture inside the bottles. For a picture of the bottle, click here. The light was provided by fluorescent bulbs for all groups. The groups were observed every three days for the average number of leaves and seeds. The average dry weight was taken at the end of the testing process.

The plants were observed every three days for the average number of leaves for each plant in the group.

The dry weight was taken after the eighteenth day of growth. The group with the pH level of 3.5 had the smallest dry weight out of the four groups. The group with the pH level of 4.5 had the highest dry weight. The group with the pH level of 7.0 had the second highest dry weight. The group with the pH level of 5.6 had the second lowest dry weight.

RESULTS

The results were not what was hypothesized. The group with the lowest pH level had the lowest average number of leaves and lowest dry weight, but the group with the second lowest pH level had the highest average number of leaves and largest dry weight. The plants normally grow at a pH level of 5.6, but the group that had the pH level of 5.6 had the second lowest average number of leaves and the second lowest dry weight.

The plants in the group with the pH level of 3.5 were very small and died after the sixth observation. The group with the pH level of 4.5 were quite tall and had the greatest average number of leaves. The group with the pH level of 7.0 had the second highest average number of leaves. The group with the pH level of 5.6 had the second lowest average number of leaves. No seeds were observed to have developed.

DISCUSSION

The results would seem to show that a certain amount of acid rain can stimulate growth, but too much could hinder it. This agrees with the results of Perkins. The group with the pH level of 7.0 grew almost as well as the group with the pH level of 4.5. This shows that Brassica Rapa rosette can grow well without any acid affecting it. The plants seemed to grow better when the pH levels were not what the plants usually grow under. This seems to show either an error in the observations or a trait in the species Brassica Rapa rosette. Further study is highly recommended.