Do Potatoes Regulate the Formation of New Sprouts?

Abstract

Did you know that potatoes have eyes? Not eyes for seeing, but eyes for making new potato sprouts. Why don't the eyes of potatoes in the store have sprouts growing out of them? Do this experiment, and watch a potato's eyes grow out!

Objective

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

Credits

Sara Agee, Ph.D., Science Buddies

Sandra Slutz, PhD., Science Buddies

Last edit date: 2013-01-10

Introduction

If you want to grow tomatoes, watermelon, corn, or most other crops, you plant the right seeds. So what do you plant when you want to grow potatoes? The answer is not a seed but another potato! When you look at a potato from the grocery store or farmer's market, you can see circular divots all over it—these are called eyes. When kept in a dark place, like planted underground or, in the case of this project, a closed paper bag, new stems start to sprout out of the potato eyes (see Figure 1 below). Over time, with the right environment and signals, roots will form at the base of the stem giving rise to a whole new potato plant capable of producing more potatoes.

Since the amount of food, water, and sunlight are often limited, some plants regulate (control) how they sprout. What about potatoes? Do they regulate their sprout growth? Can every potato eye sprout, or is there a limit to the number of sprouts that can grow from one seed potato? Does the growth of one sprout inhibit (stop) the growth of another? In this science project you'll investigate the answer to these questions using brown paper bags and lots of potatoes.

Terms and Concepts

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

• potato eye
• stem
• root
• plant growth regulation
• sprout
• plant growth inhibition

Questions

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

Bibliography

Visit this website to learn more about how potatoes are grown:

• Washington State Potato Commission. (n.d.) Production Farming. Retrieved March 14, 2012 from http://www.potatoes.com/ProductionFarming.cfm

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 retrieved March 14, 2012 from http://www.urbanext.uiuc.edu/gpe/index.html

Materials and Equipment

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

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 sprouts present on each piece of potato in the bag. Then count the total number of sprouts present for each group. You will need to add together the total number of sprouts 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 sprouts 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 sprouts grown per piece?
14. Now make another graph of your results, placing the total number of sprouts 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 sprouts grown?

Variations

• Hormones are used by plants and animals to control growth. One plant hormone is auxin. You can buy auxin at your nursery sold as "rooting hormone." Can you do an experiment showing the effect of auxin upon tuber sprouting?

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Related Links

• Science Fair Project Guide
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