The Effects of Various Soils on Brassica rapa

Abstract

Brassica rapa are plants which have been selectively bred to convenience the teacher, student, or scientist using them, and grow best in potting mix. The purpose of this experiment was to find the best alternative to the recommended potting mix based on the greatest plant height, number of leaves, number of buds, and number of flowers. It was hypothesized that the plants growing in half topsoil, half peat moss would be the best alternative to the potting mix. Six Brassica rapa seeds were planted in each of the six soil containers (two plastic containers stacked with a pellon strip laced through a center hole for water to pass into the upper container). Each soil container held six film canisters filled with that specific soil container's soil (potting mix; topsoil; peat moss; 1/2 topsoil, 1/2 peat moss; river sand; and sharp sand). The soil containers were placed in two environment boxes, a copy paper box with a fluorescent light attached. The plants were supplied with water three times a week. Results for plant height and number of leaves, buds, and flowers were recorded every four days.

River sand was the best alternative to the potting mix. Its plants had the greatest mean for the results of heights, buds, and flowers. 1/2 topsoil, 1/2 peat moss and sharp sand were the second-best alternatives, followed by topsoil and peat moss. For all dependent variables except flowers, the null hypothesis was accepted, and for the flowers, the research hypothesis was accepted.

An error in the experiment was that not enough water from the bottom container (from the first week) reached the top container. Further experimentation would clarify any inquiries this experiment has created.

Introduction

Brassica rapa are used mainly by teachers and students in the classroom or at home because of their desired traits. These traits include: shortest time span from seed to flowering, ability to reproduce seeds at high density, small plant type, fast seed development, lack of seed dormancy, ability to grow under continuous fluorescent light, and the ability to row well in potting mix (Dept. of Plant Pathology-University of Wisconsin-Madison, 1997). The purpose of this experiment is to determine if there is an alternative to the recommended potting mix (peat/vermiculite). The alternative can be used with B. rapa in classrooms and homes where the suggested potting mix is not available.

Brassica rapa are a species of plants selectively bred by Professor Paul H. Williams of the Department of Plant Pathology at the University of Wisconsin-Madison (Dept. of Plant Pathology-University of Wisconsin-Madison, 1997). These plants are of the genus Brassica, the family Brassicaceae, the order Papaverales, the class Angiospermae, the division Tracheophyta, and the kingdom Planta (WFP manual, 1989).

Professor Paul H. Williams spent 18 years breeding seven species of the family Brassicaceae, one of which was B. rapa. After fifteen years he had lessened the life cycle to five weeks (Dept. of Plant Pathology-University of Wisconsin-Madison, 1997.)

Brassica rapa were bred for specific, desired traits that would be a convenience to the teacher, student, or scientist doing research with plants (Carolina Biological Supply Co., 1997). Two of these traits are the ability to grow under continuous fluorescent light and the ability to grow well in the specific potting mix of peat/vermiculite (Dept. of Plant Pathology-University of Wisconsin-Madison, 1997). B. rapa are usually grown under these conditions, and many times kept in an environment box. The environment box is a box whose sides are covered in tinfoil and contains a thirty or thirty-nine watt fluorescent light (Carolina Biological Supply Co., 1997). Water is obtained through a thin, cotton wick/rope running from the reservoir below the plants to the soil in which the B. rapa are grown (WFP manual, 1989). The basic Brassica rapa, at maturity, grow to be approximately fifteen centimeters tall when grown in an area of 2 square centimeters (Dept. of Plant Pathology-University of Wisconsin-Madison, 1997).

Another trait of the B. rapa selectively bred by Professor Paul H. Williams was a short life cycle. The life cycle is usually complete in thirty-six to forty days. The seedling sprout and a few cotyledons appear by the third day. From day four to nine, true leaves and flower buds appear. From day ten to twelve, the stem lengthens between the points where the leaves attach. The leaves and flower buds grow larger and flowers open. From day eighteen to twenty-two, petals drop and pods lengthen and enlarge. From day thirty-six to forty, the pods can be removed from the withered plants, and the life cycle is complete (Dept. of Plant Pathology-University of Wisconsin-Madison, 1997).

In earlier research, Donna Fernandez found that, in Brassica napus, the primordia that developed next to embryos appeared to be in the embryonic phase. The embryonic phase is the first of the flowering plant stages, during which cotyledons are produced. After the embryonic stage are a few stages of growth, in which leaves are produced, and the reproductive phase. The primordia that developed next to embryos in the embryonic phase produce extra cotyledons. The primordia that developed next to embryos exiting the embryonic stage produce an extra cotyledon and leaf. The primordia that developed next to embryos that completely exited the embryonic stage became leaves. She came to her conclusion by observing the primordia developing with an electron microscope (Fernandez, 1997). Further research could be done to determine if the same happens when primordia develop next to cells that are in a stage of growth or the reproductive stage.

The Brassica rapa growing in half topsoil, half peat moss will be the best alternative to the recommended peat/vermiculite mix.

Method and Materials

To make the environment box, a 48-by-24 cm. box was used (standing upright). A single rectangular hole was cut in the uppermost part of the left and right sides. A circular hole with a three-cm. diameter was cut in the center top of the box. Also on the top panel, three rectangular holes were positioned to the north, west, and east of the center hole. Then, aluminum foil was glued to each inside panel of the box. To create a door, a 48-cm. length of aluminum foil was then cut and secured with some masking tape to the top. To weight the aluminum door, two nails were taped to the bottom of the foil. Finally, a circular fluorescent light (connected to a socket and cord) was inserted into the top center hole.

After the environment box was complete, each soil container was configured with two (2) plastic containers, one stacked atop the other. The upper container then had a single hole punched in its center. Six 35 mm film canisters (each with a hole punched in its bottom) were placed in the upper container. A piece of pellon was inserted beneath the 35 mm film canisters and a strip of pellon was laced through the hole and reached to the bottom of the bottom container. This process was repeated to create five additional soil containers.

After that, 70.2 g of peat/vermiculite potting mix was mixed with 15 ml of Miracle-Gro fertilizer solution and was evenly distributed into the six film canisters of soil container number one (the control). 142.6 g of topsoil was mixed with 15 ml of Miracle-Gro fertilizer solution and was evenly distributed into the six film canisters of soil container number two. Next, 35 g of peat moss was mixed with 15 ml of Miracle-Gro fertilizer solution and was evenly distributed into the six film canisters of soil container number three. Then, 71.3 g of top soil, 17.5 g of peat moss, and 15 ml of Miracle-Gro fertilizer solution were mixed and evenly distributed into the six film canisters of soil container number four. Next, 236.42 g of river sand was mixed with 15 ml of Miracle-Gro fertilizer solution and was evenly distributed into the six film canisters of soil container number five. Finally, 288.45 g of sharp sand was mixed with 15 ml of Miracle-Gro fertilizer solution and was evenly distributed into the last six film canisters (soil container number six).

After all the soil was placed into the film canisters, 150 ml of water was put into each of the six bottom containers. Finally, the seeds were planted and the light was plugged in.

Three times a week, for the first week, 150 ml of water was added to each soil container. And in the following weeks, 50 ml of water was added to the top container. Once the plants grew to a height at which they began to sag, they were staked with bamboo sticks. Results for the plants' height, number of leaves, number of flowers, and number of buds were recorded every four days. The type of soil that produced results greater than or equal to the results of the peat/vermiculite potting mix (average height, number of leaves, number of flowers, and number of buds) was the best alternative.

Results

For the results of the heights, in centimeters (see Table 2.1), river sand had the greatest mean (excluding the control) at 9.15. Potting mix had the greatest overall mean of 11.28. Following river sand was ½ topsoil, ½ peat moss, with a mean of 7.78. Sharp sand had a mean of 4.98. Topsoil had a mean of 1.78. Peat moss had the smallest mean of 1.6.

For the results related to the number of leaves (see Table 2.2), sharp sand had the greatest mean, 3. ½ topsoil, ½ peat moss had a mean of 2.83, the second greatest. River sand had a mean of 1.83. Both potting mix and topsoil had a mean of 1.33. Peat moss, with the least, had a mean of .83.

For the results related to the number of buds (see Table 2.3), river sand had the largest mean, 3. Sharp sand, the second largest, had a mean of 2, followed by ½ topsoil, ½ peat moss with a mean of 1.33. Potting mix had a mean of 1. Topsoil had a mean of 0.5. Peat moss had a mean of 0.

For the results related to the number of flowers (see Table 2.4), river sand, along with ½ topsoil, ½ peat moss and potting mix, had the greatest mean of 1.83. Sharp sand had the second largest mean of 0.67. With the smallest mean of buds, topsoil and peat moss had a mean of 0.

The p-value for the analysis of variance for height (see Table 3.1) was 2.98E-08. The p-value for the leaves’ analysis of variance (see Table 3.2) was .053034. The p-value for the analysis of variance of the buds (see Table 3.3) was .614593. The p-value for the analysis of variance for flowers was .048375.

Discussion

It was hypothesized that ½ topsoil, ½ peat moss would be the best alternative to the potting mix. But this experiment has shown that river sand is the best alternative. It had the greatest mean of height (excluding the control-potting mix) and buds, and it shared the greatest mean for the number of flowers. Following river sand were sharp sand and ½ topsoil, ½ peat moss that both had one mean which was the greatest mean for that specific dependent variable or equal to the greatest mean of that dependent variable. Topsoil was the third best alternative, and peat moss was the worst alternative to the potting mix.

In all cases of the dependent variables, except flowers, the level of significance was greater than .05 and the null hypothesis was accepted. But for the dependent variable "the number of flowers," the p-value was less than .05 and research hypothesis was accepted, meaning that the ½ topsoil, ½ peat moss was the best alternative only in terms of the greatest amount of flowers.

There were two limitations in this experiment. First, not enough water from the bottom container’s water supply (from the first week) reached the top container. And the other limitation was that the experiment lasted only thirty-two days, instead of the full forty days of a Brassica rapa’s lifespan.

In further research, the experimenter could use a greater number of soils to find out whether another soil is better than river sand. Also, there are many other factors from which one could derive more information/data, and thus better conclude which soil is the best alternative. For example, circumference of stem would be another factor. Further experimentation will answer any inquiries this experiment has presented.

Bibliography

Carolina Biological Supply Co. Carolina Tips. Retrieved Oct. 19, 1999 from the World Wide Web: http://www. carolina.com

Department of Plant Pathology at the University of Wisconsin-Madison. Wisconsin Fast Plants. Retrieved Sept. 26, 1999 from the World Wide Web: http://fastplants.cals.wis.edu/

Dozolme, P., Marty-Mazars, D., Clemencet, M., and Marty, F. (1995). Monoclonal antibody TeM 106 reacts with a tonoplast intrinsic protein of 106 kDa from Brassica olearacea L. [1509-1517]. Journal of Cell Science, 108 (4). Retrieved Oct. 20, 1999 from the World Wide Web: http://www.biologists.com/JCS/108/04/jcs9296.html

Fernandez, Donna E. (1997) Development basis of homeosis in precociously germinating Brassica napus embryos: phase change at the shoot apex [1149-1157]. Development, 124. Retrieved Oct. 18, 1999 from the World Wide Web: http://www.biologists.com/Development/124/06/dev0104.html

Wisconsin Fast Plants Manual. (1989) Burlington: Carolina Biological Supply Co.

Acknowledgements

I would like to thank a few people who have made this experiment much easier for me. They have helped me to understand, do, and carry through with this project. These people are my family (especially my parents), my biology teacher, my friends, and God. Thank you very much.

Appendix

Table 1.1 Raw Data-height (cm)

Table 1. 2 Raw Data-leaves

Table 1. 3 Raw Data-buds

Table 1. 4 Raw Data-flowers

Table 2. 1 Height Means

Table 2. 2 Means of Leaves

Table 2. 3 Means of Buds

Table 2. 4 Means of Flowers

Table 3. 1 P-Values (ANOVA)-height

Table 3. 2 P-Values (ANOVA)-leaves

Table 3. 3 P-Values (ANOVA)-buds

Table 3.4 P-Values (ANOVA)-flowers

Figure 2.1 Picture of the Experimental Setup

Figure 3.1 Photograph of Organism (Brassica rapa)

Figure 3.2 Photograph of Organism (Brassica rapa)

Figure 4. 1 Means of Heights of Brassica rapa

Figure 4.2 Means of Leaves of Brassica rapa

Figure 4.3 Means of Buds of Brassica rapa

Figure 4.4 Means of Flowers of Brassica rapa