AGRISCIENCE EXERCISE

University of Arkansas - AgriScience Project

AGRISCIENCE EXERCISE

PLANT SCIENCE & BIOTECHNOLOGY

Key Concept: Sexual Reproduction in Plants

Sub-Concept: Germination

Agricultural Context: Different agricultural crops have different types of seedling emergence.

Exercise: Types of Seedling Emergence

Applied Principle: Some seeds germinate and push their food source above the ground with them, while others leave the food source (cotyledons) below the ground.

Goals:

Explain the difference between hypogeal and epigeal seedling emergence.
Discuss what types of plants usually exhibit each type of emergence.
Outline advantages and disadvantages of each type of emergence.
Draw and label the progressive emergence of both hypogeal and epigeal emergence.

Preparation Time: 1 day

Materials:

4 panes clear glass, 8"x6" each, with edges taped
2 pieces of sponge/foam rubber padding, 1/4" to 1/2" thick, 8"x6" each
aluminum foil to cover glass panes
rubber bands
monocot seeds (corn, wheat, oats)
dicot seeds (soybean, clover, cotton, alfalfa)
permanent markers (Sharpie pens)
student instruction/data sheets

References: Baldwin, B. (1991). Agriscience Learning Activities Manual. Mississippi State, MS: Mississippi State University, College of Agriculture and Home Economics.

Teacher Preparation Notes:

The edges of the glass panes should be taped prior to any student contact, to avoid possible injuries
Pieces of sponge or foam rubber padding work best for the absorbent material. Paper towels, cotton cloth, and blotter paper will mold before the experiment is completed.
This activity takes about 20 days to complete, so you will need to schedule time during subsequent class periods and activities for the students to finish it.
Once the seedlings have emerged, they will all need to be placed under grow-lights or in a sunny window. If you need to set up grow-lights, be sure to allow yourself enough lead time in doing so.
The set-ups from this activity should be saved for use in the next exercise, which discusses apical and basal meristems.

Procedures for Conducting the Activity:

1. Divide the class into small groups of about 3 students each.

2. Provide each class with the necessary materials to complete this activity, as well as an instruction/data sheet.

3. Instruct the students to carefully follow the instructions for setting up the experiment.

4. Supervise each group as they set up the activity. [NOTE: Be sure that each set-up is labeled correctly before proceeding further.]

5. Allow time in each subsequent class period for the students to observe and record information about their experiments. Check their data sheets each day.

6. On days 3, 6, and 9, allow class time for students to plant more seeds in their experiment set-ups.

7. When the seedlings first emerge from the set-ups, allow the students to place them under grow-lights or in a sunny window.

8. Sometime between days 14 and 19 of the experiment, allow one class period for the students to complete their data sheets and discuss the results of the activity.

9. Keep the set-ups intact for use with the next exercise, Apical and Basal Meristems. Do not allow students to alter or destroy the work they have done so far!

AGRISCIENCE EXERCISE

Types of Seedling Emergence

Student Instructions/Data Sheet

Note: Be sure to carefully read the entire exercise before beginning the experiment. Failure to follow the instructions may cause the experiment to be unsuccessful.

1. Construct an experiment set-up by layering one glass pane, one layer of absorbent material (sponge), a few monocot seeds, and a second glass pane as shown in Figure A.

2. Secure using rubber bands.

3. Construct a second set-up, using dicot seeds.

4. Take both set-ups to a sink, and thoroughly soak the padding in each. (Re-water as necessary throughout the experiment.)

5. Wrap each set-up in aluminum foil, so that the seedlings can emerge from the top, but no light can get to the plant roots. See Figure B.

6. Using a permanent marker, label each set-up with your group's name and the type of seed planted.

7. Check them each day, recording your observations on the data sheet. Don't forget to keep the padding moist.

8. On the day the seedlings emerge from the top, place the set-ups under a grow-light or in a sunny window.

9. On days 3, 6, and 9 of this activity, add 3 more monocot and dicot seeds to the respective set-ups. [You will be able to see the progressive emergence of both monocot and dicot seeds at the end, since the seedlings will be in different stages of development.]

10. Continue to record your daily observations on the data sheet.

11. Approximately 14 to 19 days after the first seeds were planted, remove the foil from each set-up and draw the progressive emergence of the two types of seeds in the space provided on your data sheet.

12. Answer the discussion questions; be prepared to discuss the answers in class.

GROUP DATA SHEET

Types of Seedling Emergence

Daily Observations [NOTE: Don't forget to water seeds!]

Monocot Seeds _____________ Dicot Seeds ______________

Day 1: __________________________ _____________________________

Day 2: __________________________ _____________________________

Day 3: __________________________ _____________________________

Day 4: __________________________ _____________________________

Day 5: __________________________ _____________________________

Day 6: __________________________ _____________________________

Day 7: __________________________ _____________________________

Day 8: __________________________ _____________________________

Day 9: __________________________ _____________________________

Day 10:__________________________ _____________________________

Day 11:__________________________ _____________________________

Day 12:__________________________ _____________________________

Day 13:__________________________ _____________________________

Day 14:__________________________ _____________________________

Day 15:__________________________ _____________________________

Day 16:__________________________ _____________________________

Day 17:__________________________ _____________________________

Day 18:__________________________ _____________________________

Day 19:__________________________ _____________________________

Day 20:__________________________ _____________________________

Progressive Emergence Drawings

Draw the progressive emergence of monocot seedlings demonstrated in this activity in the space provided below:

Draw the progressive emergence of dicot seedlings shown in this activity below:

Discussion Questions

Answer the following questions completely. You will be expected to share and discuss your answers in a class discussion.

1. Based on what you observed in this activity, what are the advantages of epigeal emergence?

__________________________________________________________________

What are the advantages of hypogeal emergence?

__________________________________________________________________

2. What are the disadvantages of each type of emergence?

Epigeal:____________________________________________________________

__________________________________________________________________

Hypogeal:__________________________________________________________

__________________________________________________________________

3. Grasses establish a taproot upon germination. This is later replaced with fibrous roots. Why do you think it is important for the plant to put out the taproot first?

__________________________________________________________________

TEACHER BACKGROUND SHEET

Types of Seedling Emergence

Epigeal: The cotyledons are pushed above the soil surface due to the elongation of the hypocotyl. Most legumes, such as soybeans, alfalfa, and red clover have epigeal emergence.

Hypogeal: The cotyledons (food supply) remain below the soil surface during emergence. Cereals such as wheat, rye, corn, oats and rice have hypogeal type emergence. Some legumes, such as peas, have hypogeal emergence.

***Refer to IMS Texas A & M University lesson plan "Plant Growth and Development: Seed Germination" for information***

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