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.

Question: Do plants produce chemicals that pervent germination of nearby seedlings?


1. Crush one whole tomato and strain the crushed tomato into a beaker

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. Report your results.

What Other Chemicals Inhibit Germination?

Choose a chemical from the list below and design an experiment to determine if it inhibits germination of tomato.


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.

Other Plant Experiments

How Do Hormones Affect Plant Growth - use gibberellic acid to show how plants respond to growth hormones

Leaf Transpiration - use leaves from trees to analyze how much water is lost when they are exposed to light

Chromatography: Separation of Plant Pigments - use chromatography to show how leaves contain pigments that separate

Rate of Photosynthesis - using baking soda, elodea and light, measure the bubbles to observe how fast a plant photosynthesizes and releases oxygen