Does Plant Density Affect Plant Growth?

Author(s): Brandon Duran and Laurie Aiello
Growth & Development Experiment 
SED 695B; Fall 2005

Research Question:

How does an increase in population density affect plant growth?

 

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Standards addressed:

Biology:
6. Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept:

a.

 

Students know biodiversity is the sum total of different kinds of organisms and is affected by alterations of habitats.

b.

 

Students know how to analyze changes in an ecosystem resulting from changes in climate, human activity, introduction of nonnative species, or changes in population size.

d.

 

Students know how water, carbon, and nitrogen cycle between abiotic resources and organic matter in the ecosystem and how oxygen cycles through photosynthesis and respiration.

e.

 

Students know a vital part of an ecosystem is the stability of its producers and decomposers.
Independent variable
Dependent variables
Controls
Series
Time
Seed Density
Amount of Water 		Plant Height
Plant Color
   Height of Plant Over Time
Materials
Procedures
  • Cups
  • Soil
  • Radish Seeds
  • Water
  • Balance
  1. Fill 5 cups with an equal amount of soil. It may be helpful to use a plant starter kit.
  2. Label the cups 1 Radish seed, 2 Radish seeds, 4 Radish seeds, 8 Radish seeds, and 16 Radish seeds.
  3. Equally distribute the number of seeds indicated in each cup.
  4. Water each cup with an equal amount of water.
  5. Each day, take a picture of the plants, and record any observations you notice (height, color, etc.)
 
Plant Height Data
Number of Plants Average Plant Height (cm)
Day 1 Day 2 Day 3 Day 4
1        
2        
4        
8        
16        
Plant Growth Data
Number of Plants Average Plant Growth (cm)
Day 2 Day 3 Day 4 Day 5
1        
2        
4        
8        
16        
To the left you see some sample data charts to use. You will of course want to add more days to the chart.
Plant Height Data
# of Seeds Average Plant Height (cm)              
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Day 9
Day 10
1
0.00
0.00
0.00
1.72
4.37
7.97
10.30
11.90
12.45
13.13
2
0.00
0.00
0.80
2.99
5.50
8.49
10.09
11.04
11.45
12.08
4
0.00
0.00
0.00
2.86
6.16
8.95
11.04
12.02
12.76
13.63
8
0.00
0.00
0.00
2.88
5.08
8.30
9.79
11.17
11.40
12.00
16
0.00
0.00
0.00
3.13
5.77
8.80
10.17
11.50
11.80
12.20
Plant Growth Data
# of Seeds Average Plant Growth (cm)              
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Day 9
Day 10
1
N/A
0.00
0.00
1.72
2.65
3.60
2.33
1.60
0.55
0.68
2
N/A
0.00
0.80
2.19
2.51
2.99
1.60
0.95
0.41
0.64
4
N/A
0.00
0.00
2.86
3.30
2.79
2.09
0.98
0.73
0.88
8
N/A
0.00
0.00
2.88
2.19
3.23
1.49
1.37
0.23
0.60
16
N/A
0.00
0.00
3.13
2.63
3.03
1.37
1.33
0.30
0.40
Some Sample Data from a radish seed experiment.
Click Here to view the sample graph of plant height over time
 All graphs generated from above data.
Click Here to view the sample graph of plant growth over time
   

References & Links: