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The effect of vitamin D on plant growthFeatured science projectScience project video


The materials required for this science fair project:
- 30 small plastic pots
- enough soil to fill the 30 pots
- vitamin D tablets
- 10 beakers
- 1 measuring cylinder
- 50 radish seeds
- 50 green beans
- 50 chili seeds
- 1 digital weighing scale
- 1 spatula
- 1 black marker pen
- 1 long ruler


1. For this science fair project, the independent variable is the concentration of vitamin D used to water the plants and the type of plant used – radish, green beans and chili plants. The dependent variable is the growth height of the plants. This is determined by measuring the height of the plants with a ruler. The constants (control variables) are the number of plants in the pot, the size of the pot and the amount of soil in the pot.

2. The pots are prepared by filling  soil in  30 pots. The pots are labeled as radish 0 to radish 9, green bean 0 to green bean 9, and chili 0 to chili 9. Five seeds are placed in each pot according to the label  on the pots. More seeds can be placed in each pot and the additional germinated plants removed on the 5th day. The pots are watered every day with tap water and the seeds are allowed to germinate over the next 5 days.

3.  Ten beakers are labeled as 0 to 9.  Vitamin D tablets are crushed and 0.1 gram is added to beaker 1, 0.2 gram is added to beaker 2, 0.3 gram is added to beaker 3 and so on until 0.9 gram is added to beaker 9. The beaker labeled 0 will have no vitamin D. 100ml water is then poured into each beaker and stirred  with a spatula.

4. The plants are watered using the water from the beakers for the next 10 days according  to the number on the beaker and  on the pot. For example, the pot labeled as “chili 5” will be watered using water from beaker 5 with a vitamin D concentration of 0.5grams/100ml water.

5. After the tenth day, the height of the 5 plants in each pot is measured. The height of the 5 plants in each pot is totaled and divided by 5 to obtain the average height and.

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Time required:
5 days to prepare, 10 days for science fair project
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Easily found
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