Problem: How does the amount of light affect the growth rate of a seed?Literature Search: This experiment is only trying to verify the answer since this question has been proven before. Others have also proven that seeds germinate at the same rate at the early stages no matter how much or how little sunlight there is. Once the radicle brakes trough and the plant starts to use photosynthesis to produce energy and grow. Since sunlight is needed in photosynthesis, the plant with more sunlight starts to grow more rapidly then the plant that lacks sunlight. Hypothesis: If the seed is exposed to sunlight then the seed will grow more then the seed that is kept in the dark.
Experimental design: I took the four seeds and divided theme into groups of two. I placed theme inside a paper towel which was inside a cup. I water both of the cups and placed one in the closet, where it was dark. The other cup I placed on the ledge, where there was a large amount of light at all times. Each day I provided the seed with the equal amount of water. In this experiment I had one control which was the plant in the dark.
Results and conclusion: My hypothesis was correct. As you can see from the data graphs at first the seeds germinated at the same rate until the tip of the radicle broke trough and was visible. Afterwards the seed which was in the light grew more rapidly then the seed which was in the dark. I think this happened because when the seed is in the early stages of germination it does not use light to grow but is controlled by phytochrome. Which is a hormone that controls the germination of a seed before it reaches light. After the radicle broke trough, the seed needed sunlight for photosynthesis, so they plant which was deprived of sunlight grew slower then the plant which got sunlight.
REFERENCES:1. Hartman, H. . Plant Propagation.
Englewood Cliffs, NJ: Prentice Hall. , 1990. Janick, J. 2. Horticultural Science. New York: W.
H. Freeman and Co. , 1986.
