Abstract

Objective

In this experiment you will test if potato plants regulate the production of new roots.

Introduction

Plants need water and nutrients to grow. The roots bring the water and nutrients to the plant, and also store food for the plant that has been made by the leaves. To get nutrients from the soil roots branch out in every direction to absorb as many nutrients from the surrounding soil as possible.

Some plants send deep tap roots into the soil, while other plants spread out a network of roots just below the soil surface. Plants like potatoes develop tubers, or nodules, in thier root system to store food. Each plant has its own unique pattern of root growth that depend upon the plant's native environment. Plants from the rainforest, like orchids and epiphytes, grow roots that absorb water from the air!

Because each plant grows roots in such a particular way, root growth for each plant must be regulated. How is the growth of a root regulated? Is there a limit to the number of roots that can grow? In this experiment you can investigate these questions using potatoes.

Terms, Concepts, and Questions to Start Background Research

To do this project, you should do research that enables you to understand the following terms and concepts:

• roots
• inhibition
• regulation
• growth
• nutrients

• How do potatoes grow roots?
• Is root growth in a potato regulated?
• Which part of a potato can grow roots?

Bibliography

• Visit the website of "The Great Plant Escape" to help Detective Le Plant solve 6 cases, learn about plants, use the glossary to learn new terms and see pictures of plant parts:
  Stack, Greg, et. al. 2005. "The Great Plant Escape." University of Illinois, Urbana-Champaign. [12/13/05]
  http://www.urbanext.uiuc.edu/gpe/index.html
• VanCleave, Janice. 1993. Janice VanCleave's A+ Projects in Biology. New York, NY: John Wiley & Son's Inc. pp 51–61.
• Vecchione, Glen. 2001. 100 Award Winning Science Fair Projects. New York, NY: Sterling Publishing, Inc. p 164.

Materials and Equipment

• eight large potatoes
• knife (get your parents to help!)
• cutting board
• brown paper lunch bags
• rubber bands

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Experimental Procedure

1. Leave the first potato whole and put into a brown paper bag. Close the paper bag with a rubber band.
2. Get a parent to help you with a knife and cutting board to cut the rest of the potatoes.
3. Cut one large potato into two equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
4. Cut the next potato into three equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
5. Cut the next potato into four equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
6. Cut the next potato into five equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
7. Cut the next potato into six equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
8. Cut the next potato into seven equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
9. Cut the next potato into eight equal pieces and put the pieces in a brown paper bag. Close the paper bag with a rubber band.
10. Leave the bags out at room temperature for two weeks in a cool dark place with good circulation.
11. Remove the potatoes from each bag carefully, collecting two types of data for each group. First count the number of roots present on each piece of potato in the bag. Then count the total number of roots present for each group. You will need to add together the total number of roots for each piece of potato in the bag.
12. Record your results in a data table:

    Piece:	#1	#2	#3	#4	#5	#6	#7	#8	Total	Average
    Bag #1		-----	-----	-----	-----	-----	-----	-----
    Bag #2			-----	-----	-----	-----	-----	-----
    Bag #3				-----	-----	-----	-----	-----
    Bag #4					-----	-----	-----	-----
    Bag #5						-----	-----	-----
    Bag #6							-----	-----
    Bag #7								-----
    Bag #8

13. Make a graph of your results, placing the average number of roots per piece on the left (Y-axis) and the number of pieces on the bottom (X-axis) of the graph. Is there a correlation between the number of pieces that the potato was cut into and the average number of roots grown per piece?
14. Now make another graph of your results, placing the total number of roots on the left (Y-axis) and the number of pieces on the bottom (X-axis) of the graph. Is there a correlation between the number of pieces that the potato was cut into and the total number of roots grown?

Variations

• Hormones are used by plants and animals to control growth. Another way that root growth in plants is regulated is by the hormone auxin. You can buy auxin at your nursery sold as "rooting hormone." Can you do an experiment showing the effect of auxin upon rooting?
• In this experiment you find out about how the potato plant regulates rooting. How do other plants regulate rooting? Do other plants make roots the same way? Do the same parts of different types of plants make roots? Compare rooting in different plants like cut geranium, carrot, lettuce, cabbage, onion, garlic, etc... Try different plants and see where the roots come from.

• For more science project ideas in this area of science, see Plant Biology Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2006-01-31 22:35:26