The Effects of pH and Temperature on the Germination of Raphanus sativus Seeds

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The Effects of pH and Temperature on the
Germination of Raphanus sativus Seeds

• Keara Miley Lake Shore
• Robin Smith Lake Shore

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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

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How does pH affect germination?

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

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Temperature affecting Germination

• If temperature is too high, moisture evaporates
  from the soil
• If temperature is too low, water absorption slows

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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

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Problem

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

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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

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Values
pH pH pH Temperature (C) Temperature (C) Temperature (C)
- Standard - Standard
4.0 6.0 8.0 28 30 35
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Materials

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

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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

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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

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Procedure
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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

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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

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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

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Observations
Date Observation
March 29 Bags and seeds are set up
April 1 All standards have germinated and quite a few of the ones in the incubator. No germination in the refrigerator
April 2 More have germinated in the incubator. Still no germination in the refrigerator
April 5 Still no germination in the refrigerator. We will retry this part in warmer area of 28C
April 11 Seeds germinated in the warmer temperature
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Hypothesis

• Hypothesis was accepted
• Most seeds germinated in 35C temperature and pH
  level of 4.0

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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

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Recap

• Set the seeds in areas of different temperatures
• Recorded how many seeds germinated after three
  days
• Found a temperature of 35C and pH of 4.0
  germinated the most

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Design Flaws and Errors

• Testing in an area of 22C was too cold
• Retested in an area of 28C
• Initially added too much citric acid and baking
  soda

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Further Study

• Different levels of pH
• Wider ranges of temperatures
• Different types of plants
• Different soil types

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Real Life Application

• Retailers find best source to buy stock
• Profits increase

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Questions?
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