Show That Fruits Contain Germination Inhibitors

What You Need to Know

In reference to plants, an inhibitor is a chemical that blocks plant growth. A germination inhibitor is a chemical that prevents the germination of seeds.

How Does a Germination Inhibitor Work?

Plants can produce their own germination inhibitors. The germination inhibitor produced by a plant prevents the germination of its own seeds until conditions are favorable for them to develop. Common substances that seem to reduce seed germination include tomato juice, lemon peel, onion juice, apple cider, and the water in which carrots or spinach have been cooked.

What Does This Have to Do with Fruits?

Most fruits contain germination inhibitors, which prevent the seeds from germinating while they are inside the fruit. When the fruit falls to the ground, and its fleshy part decays, water washing over the soil will wash the inhibitor off the seed. The seed from the fruit can then grow.

Real-Life Science Challenge

Inhibitors in one plant can prevent the growth of another plant. Some plants, such as sweet potatoes, release special chemicals called allelochemicals that prevent other plants from growing too close to them. Organic gardeners use plants that contain allelochemicals to keep weeds away from crops, and scientists are looking for ways to use allelochemicals as natural weed killers.

Fun Fact

When animals, such as birds and bats, swallow seeds, the germination inhibitors are removed as the seeds pass through the digestive system of the animal. When these seeds are eliminated from the body along with the animal's feces, they are ready to germinate.

Experiment

Now, start experimenting with ways to show that different fruits contain germination inhibitors.

Hints

• The germination inhibitor might be in the seed coat or it might be in the flesh of the fruit.
• Try making extracts of different fruits and different fruit parts.
• Determine the effect of the fruit extracts on the germination of seeds.

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