Effect of caffeine on plant growth
The materials required for this science fair project:
- 1 packet of mung beans
- 3 gardening pots
- Enough soil to fill the 3 pots
- Gardening utensils
- Tap water
- Caffeine tablets
- Coffee powder
- 2 beakers
- 1 measuring cylinder
- 1 digital weighing scale
- 1 black marker
1. For this science fair project, the independent variable is the solution used to water the plants – water, caffeine solution and a coffee mixture. The dependent variable is the growth of the mung bean plants. This is determined by measuring the height of the plants every day using a ruler. The constants (control variables) are the size of the pot, the concentration of caffeine and coffee, the amount of sunlight, the temperature of the environment (which will remain at room temperature) and the amount of water added daily.
2. Fill the 3 pots with equal amounts of soil. Plant ten mung beans in each pot and allow them to germinate. Additional seeds can be placed in the pots in case some of the seeds do not germinate; the additional plants can be removed later.
3. For the first 5 days, water the 3 pots with tap water only. Allow the seeds to germinate for the first 5 days.
4. After 5 days, measure the height of the 10 plants in each pot. Add up the individual heights and divide by 10 to obtain the average height. Record the average heights in a table, as shown below.
5. Prepare the caffeine solution by dissolving 10g of caffeine tablets in 100ml of water in a beaker. Label the beaker ‘caffeine’. Similarly, add 10g of coffee to 100ml of water in another beaker and label it ‘coffee’.
6. Label the 3 pots ‘water’, ‘caffeine’ or ‘coffee’. Over the next 10 days, water the pots once a day with 100ml water, caffeine solution or coffee mixture, according to the labels on the pots.
7. Measure and calculate the average height of the mung bean plants every day for the next 10 days. Record all calculations in a table, as shown below.