Detergent & Seed Germination
Introduction:
Seeds come in different sizes, shapes, and colors. Some are edible and some are not. Some seeds germinate readily while others need specific conditions to be met before they will germinate. Within every seed lives a tiny plant or embryo.The outer covering of a seed is called the seed coat. Seed coasts help protect the embryo from injury and also from drying out. Seed coats can be quite thin and soft as in beans or very thick and hard as in locust or coconut seeds. Endosperm, which is a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These generally are the first parts visible when the seed germinates. Plants are classified based upon the number of seed leaves (cotyledons) in the seed. Plants such as grasses and grass relatives can be monocots, containing one cotyledon. Dicots are plants that have two cotyledons.
Seeds remain dormant or inactive until conditions are right for germination. All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while other require darkness to germinate.When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. The embryo’s cells start to enlarge and the seed coat breaks open and root or radicle emerges first, followed by the shoot or plumule which contains the leaves and stem.
Many factors contribute to poor germination. Over-watering results in a lack of proper oxygen levels. Planting seeds to too deep results in the seed using up all of its stored energy before reaching the soil surface, and dry conditions result in the lack of sufficient moisture to start and sustain the germination process.
Objective:
The students will be able to describe how some environmental factors affect seed germination.
Materials:
Masking tape, Scissors, 3 ziplock bags, Marker, Forceps, Paper Towels, Metric Ruler, 3 colored pencils, 25 seeds, distilled water, 50 ml graduated, 1% detergent solution, 10% detergent solution, graph paper
Procedure:
- Label the 3 zip lock bags: Control, 1% Solution and, 10% Solution.
- Cut 6 square pieces of paper toweling to fit each bag.
- Place 2 squares in each bag.
- Distribute 6 seeds on each side of the paper towel between the plastic and towel.
- In the control bag add 25 ml of distilled water completely moistening the paper towel.
- In the 1% solution bag add 25 ml of 1% detergent solution making sure to completely moisten the towel.
- Do the same to the 10% solution bag by adding 25 ml of 10% detergent solution.
- Make sure all bags are sealed tightly.
- Place the bags in a dark warm place designated by the instructor.
- Write a hypothesis predicting the results of the experiment.
- Examine the bags daily for 5 days. Record any changes that might have occurred. If the roots is visible the seed is considered germinated.
- Record your date in the table below.
- Do not allow your towels to dry out. Moisten each bag with the appropriate solutions in equal amounts.
- Measure the root growth of each seed daily from the time it appeared.
- Graph the data from the table using the colored pencils to represent each of the zip lock bags.
Number of Seeds Germinated
| Day |
Control |
1% Detergent Solution |
10% Detergent Solution |
| 1 |
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| 2 |
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| 3 |
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| 4 |
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| 5 |
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Average Growth of Germinating Seeds(mm)
| Day |
Control |
1% Detergent Solution |
10% Detergent Solution |
| 1 |
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| 2 |
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| 3 |
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| 4 |
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| 5 |
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Graph Title: ________________________________________
Analysis:
1. How many of the seeds germinated after 5 days in distilled water? ________. In 1% solution? _______ in 10% solution? ________.
2. Was there a difference in the number of seeds germinated?
3. In which of the three bags did seeds germinate faster?
4. What was the purpose of the control?
5. Did the detergent strength have an effect on the seed’s germination? If so What was it?
6. Was your hypothesis correct? Why or why not?
7. If it was not, what will you do now?
