Germination Inhibitors

Background - As a seed germinates, new cells are produced. As they grow larger, they differentiate into plant organs, such as roots, stems, leaves, and flowers. Tomato seeds will usually germinate when exposed to the proper amounts of moisture and oxygen and fairly warm temperature. Interestingly enough, these seeds do not germinate while they are inside the tomato. How can this be?

Question: Do plants (particularly the tomato fruit) contain hormones that pervent germination. What effect does a germination inhibitor from one ind of tomator have on other kinds of tomatoes?


1. Crush one whole tomato (Variety A) and strain the crushed tomato into a beaker - label the beaker EXTRACT A
2. From the tomato pulp of the tomato remove about twenty seeds and wash them.
3. Place 10 seeds in one petri dish lined with moistened paper towels or filter paper.
4. Place 10 seeds in another petri dish moistened with extract A.
5. Over a period of several days, observe the seeds, add more water or extract to keep the paper moist.
6. Record the data.

To determine the effects of another tomato on germinating seeds, obtain a different kind of tomato (Variety B). Discuss with your lab group how you will design this experiment (using the above procedure as a guideline)


1. What are the controls in your experiment? Why did you wash the seeds?


2. Explain how you determined whether or not a seed has germinated.


3. What conclusions can you draw from the results: do tomatoes contain germination inhibitors? Do these inhibitors work for other types of tomato?


4. In addition to tomatoes, what other fruits or vegetables probably contain germination inhibitors?


5. Discuss some practical applications of germination inhibitors.