The Effects of pH and Temperature on the Germination

of Raphanus sativus SeedsKeara Miley – Lake Shore

Robin Smith – Lake Shore

Miley -- Smith 2

Terminology

• Two-Factor Design of Experiment – (DOE)

• Raphanus sativus – (Radish)

• Germination– When a seed starts to sprout

• pH– How alkaline or acidic a substance is

Miley -- Smith 3

How does pH affect germination?

• pH affects germination because the acid breaks down the seed coat and allows more water to get absorbed

Miley -- Smith 4

Temperature affecting Germination

• If temperature is too high, moisture evaporates from the soil

• If temperature is too low, water absorption slows

Miley -- Smith 5

Why Do The Experiment?

• More areas we can grow food, the more food we can grow

• The purpose of the experiment was to find the pH level and temperature that would cause the most Raphanus sativus (radish) seeds to germinate

Miley -- Smith 6

Problem

• How do different levels of pH and temperature affect the germination of radish seeds?

Miley -- Smith 7

Hypothesis

• If the surrounding temperature is 35ºC and the pH level of the water sprayed on the seeds is 4.0, then the most radish seeds will germinate

Miley -- Smith 8

Values

pH Temperature (°C)

- Standard + - Standard +

4.0 6.0 8.0 28 30 35

Miley -- Smith 9

Materials

• Source of tap water• Analytical balance• 100 mL spray bottles• Paper towels• Ziploc bags• Incubator (35°C)• Refrigerator• pH test strips• tweezers

Miley -- Smith 10

Procedure

• We mixed the water with either baking soda or citric acid to change the pH and get a high, a low, and a standard concentration

• We sprayed the concentrations onto the radish seeds placed in Ziploc bags

Miley -- Smith 11

Procedure

• We then placed the bags into areas with the different temperature levels

• After 3 days, we recorded the number of seeds that germinated in a table

Miley -- Smith 12

Procedure

Miley -- Smith 13

Data Analysis

• The effect of pH on the germination of radish seeds was -0.17 units

• On average, as pH increased, the number of seeds germinated decreased by 0.17 units

88.17

0

2

4

6

8

10

-1 1

pH

Nu

mb

er

of S

ee

ds

Ge

rmin

ate

d

Miley -- Smith 14

Data Analysis

• The effect of temperature on the germination of radish seeds was 0.5 units

• On average, as temperature increased, the number of seeds germinated increased by 0.5 units

8.33

7.83

0

2

4

6

8

10

-1 1

Temperature (°C)

Nu

mb

er

of S

ee

ds

Ge

rmin

ate

d

Miley -- Smith 15

Data Analysis

• There may be an interaction between the two line segments because they are not parallel

• The effect of the graph is 0.16 units

8.33

7.67

8.338

0

2

4

6

8

10

-1 1

Temperature C

Num

ber o

f See

ds G

erm

inat

ed

Miley -- Smith 16

Observations

Date Observation

March 29 Bags and seeds are set up

April 1All standards have germinated and quite a few of the ones in the incubator. No germination in the refrigerator

April 2More have germinated in the incubator. Still no germination in the refrigerator

April 5Still no germination in the refrigerator. We will retry this part in warmer area of 28°C

April 11 Seeds germinated in the warmer temperature

Miley -- Smith 17

Hypothesis

• Hypothesis was accepted

• Most seeds germinated in 35°C temperature and pH level of 4.0

Miley -- Smith 18

Recap

• Set out to find what pH level and temperature germinated the most seeds

• We hypothesized that most seeds would germinate at 35ºC and a pH of 4.0

• Conducted experiment

• Sprayed different pH levels on radish seeds

Miley -- Smith 19

Recap

• Set the seeds in areas of different temperatures

• Recorded how many seeds germinated after three days

• Found a temperature of 35°C and pH of 4.0 germinated the most

Miley -- Smith 20

Design Flaws and Errors

• Testing in an area of 22°C was too cold– Retested in an area of 28°C

• Initially added too much citric acid and baking soda

Miley -- Smith 21

Further Study

• Different levels of pH

• Wider ranges of temperatures

• Different types of plants

• Different soil types

Miley -- Smith 22

Real Life Application

• Retailers find best source to buy stock– Profits increase

Miley -- Smith 23

Miley -- Smith 24

Miley -- Smith 25

Miley -- Smith 26