Tag Archives: germination

OS5 What Seeds Need to Grow

Different kinds of seeds end up on or in the ground in different ways. Pumpkin seeds are inside a pumpkin. Lots of animals eat pumpkins and the seeds. The seeds may just fall on the ground and be forgotten by the animal. Or the pumpkin may not get eaten but just rot and the seeds fall to the ground. However a seed gets to the ground, once there it wants to grow. How does a seed know it’s time to grow? Let’s find out about some things that might affect when and how a seed grows.

 

Question: Do light, water and temperature matter to a pumpkin seed and sprout?

Materials:

3-Styrofoam cups filled with dry potting soil (Let the soil sit out in a tray to dry, stirring it every day until it is very dry.)

3-Styrofoam cups filled with potting soil

24-Pumpkin seeds

Water

Plastic wrap

Flashlight

Metric ruler

A dark closet or box, a refrigerator [ask first], a warm, light counter

 

project set up

Each cup must be labeled so it is put in the right place. When the cups are compared later, the labels tell which cup is which.

Procedure:

Step 1: Open your Science Journal, write “Investigation 5” and the date. Draw Tables 1 and 2 in your journal.

Step 2: Label the cups DW, DY, LW, LY, CW, CY [D dark, L light, C cold; Y dry, W wet].

Step 3: Add water to all the cups with a W label so the dirt is damp but not muddy.

Step 4: Push two seeds 2cm deep in each cup, cover them and firm the dirt. Remember the best way from Investigation 4.

Step 5: Lay two seeds on top of the dirt in each cup.

Step 6: Cover the cups with plastic wrap.

Step 7: Put the two cups with a D label in a warm, dark closet or under a box.

Step 8: Put the two cups with an L label in a warm light place.

Step 9: Put the two cups with a C label in the refrigerator.

Step 10: Check the seeds everyday until the first seeds start to germinate. Take the plastic wrap off.

Step 11: Check and measure the sprouts everyday for seven days. Measure only the length of the stem. Try to do the ones in the closet quickly and use a flashlight with the door closed so they stay in the dark as much as possible. If the cups are under a box, wait until the room is dark and use a flashlight. Don’t shine the flashlight on the sprouts.

Note: Some of the seeds may not sprout. Start counting the seven days when the first seeds germinate.

Observations:

Write down how long each sprout is in the table and what it looks like in your notes.

 

pumpkin sprouts

Only a couple of cups had pumpkin seeds germinate. Can you tell which one was in the light? Why are the tips of the cotyledons dark green when the rest is yellow green?

Conclusions:

Are the seeds pushed into the dirt in the light or in the dark? Why do you think so?

Is this the same as putting the seeds in a dark closet? Why do you think so?

Why are some seeds pushed into the dirt and others left on top?

Does it matter if the seeds are in the light or dark to germinate? Why do you think so?

Does it matter if the sprouts are in the light or dark to grow? Why do you think so?

Does it matter if the seeds are wet or dry to germinate? Why do you think so?

Does it matter if the seeds are wet or dry to grow? Why do you think so?

Do you think how wet a seed is would matter? Can you think of a way to test your opinion? When you have, try it and find out if it matters how wet a seed is.

Does it matter if the seeds are warm or cold to germinate? Why do you think so?

Does it matter if the seeds are warm or cold to grow? Why do you think so?

Do you think these results would be true for all seeds? Why do you think so?

Which two cups do you think these are? Why do you think so?

Why do you think the tips of some cotyledons in the cup on the right are green when the rest is yellow?

[The dark green seedlings were in the light. The yellow green seedlings were under a box. The tips of the cotyledons poked out under the edge of the box.]

OS4 Which Way Should a Seed Point

In nature a seed might fall on the ground or get buried in mud or by an animal. When a gardener plants a seed, that person can point the seed any direction. Let’s find out if there is a best way to plant a pumpkin seed.

 

Question: Does it matter which end of a seed points down?

supplies for the Investigation

Materials:

6 Pumpkin seeds

Small clear glass or jar with straight sides

Paper towel

Cardboard

Scissors

 

Procedure:

Step 1: Open your Science Journal, write “Investigation 4” and the date.

Step 2: Cut a strip of cardboard 1.5cm shorter than the glass or the jar shoulder and 2.5cm longer than the circumference of the glass or jar.

Step 3: Roll up the cardboard strip and slip it into the glass or jar to make sure it fits. When you let it go, the cardboard should unroll against the glass. You may have to push it out a little. Take the cardboard out again.

Step 4: Fold the paper towel so it fits around the outside of the cardboard ring.

Step 5: Roll the cardboard and paper towel up and put them into the glass or jar so the paper towel touches the glass. It must be very tight. You may need to fasten the cardboard ring with a paperclip to keep it tight.

pumpkin seeds in jar

The cardboard holds the pumpkin seeds firmly against the glass. The paper towels will pull water up to the seeds. Each seed points a different direction.

Step 6: Carefully slide the pumpkin seeds about half way down between the paper towel and glass so two point in each different direction, up, down and sideways. This can take patience and maybe a thin knife to push the seeds around. The seeds must be at least 3cm from the top and 3cm from the bottom.

Step 7: Pour 2cm water into the glass and set it aside. The water will soak up into the paper towel. Make sure about 1.5 – 2cm of water is left in the jar. You may have to add some water to do this. Cover the glass with plastic wrap or put the lid loosely on the jar and set it aside.

Step 8: Check the seeds everyday until they germinate and start to grow. Draw them in your Journal.

Step 9: After the radicle comes out, watch for the cotyledons. Draw them in your Journal.

 

Observations:

Seed 1: Which direction does it point?

How many days until it germinates?

What does the root do?

What does the cotyledon do?

 

Seed 2: Which direction does it point?

How many days until it germinates?

What does the root do?

What does the cotyledon do?

 

up and down pointing seeds germinate

Radicles start growing down as soon as a pumpkin seed germinates.

Seed 3: Which direction does it point?

How many days until it germinates?

What does the root do?

What does the cotyledon do?

 

Seed 4: Which direction does it point?

 

How many days until it germinates?

What does the root do?

What does the cotyledon do?

 

Seed 5: Which direction does it point?

How many days until it germinates?

What does the root do?

What does the cotyledon do?

 

Seed 6: Which direction does it point?

How many days until it germinates?

What does the root do?

What does the cotyledon do?

 

Conclusions:

What happens to the radicle [baby root] when it starts to grow?

 

Why is it important for the radicle to do this?

 

What do you think causes the radicle to do this?

 

germinating pumpkin seed

A pumpkin sprout comes out of the little flat space at one end of a seed.

What happens to the sprout when it starts to grow?

 

Why is it important for the sprout to do this?

 

What do you think causes the sprout to do this?

 

up and down seed radicles

A radicle must grow around to go down when a pumpkin seed points up. A radicle grows straight down when the seed point down.

Which is the best way to plant a pumpkin seed?

 

OS3 How a Pumpkin Seed Germinates

A seed is much smaller and looks a lot different than the plant it came from. The parts of a seed must change for the seed to become a plant. Let’s take a look at some of those changes.

 

Question: How does a seed change as it germinates [sprouts]?

materials for OS3

Materials:

2 Pumpkin seeds

Custard cup or other small shallow cup

Paper towel

Plastic wrap

Metric ruler

 

Procedure:

Step 1: Open your Science Journal, write “Investigation 3” and the date. Draw Table 1 in your journal.

Step 2: Label the outside of the custard cup ‘1’ and ‘2’ on opposite sides.

Step 2: Put a double layer piece of paper towel in the bottom of the custard cup.

Step 3: Add enough water to make the towel wet but not soggy.

Step 4: Measure the length, width and fatness of the 2 seeds in millimeters. You can use the same method you used in Investigations 1 and 2. Write the measurements in for Day 0.

setting the project up

After measuring the length, width and fatness of the pumpkin seeds, put them on the moist paper towel in the custard cup.

Step 5: Put Seed 1 on the side labeled 1 and Seed 2 on the side labeled 2 on the wet paper towel.

Step 6: Cover the top of the custard cup with plastic wrap. You may need to use a rubber band to keep the plastic wrap on.

Step 7: Measure the 2 seeds every day until they start to grow. Be sure the paper towel stays moist.

 

Observations:

Table 1:

 table for measurements

 

Draw the germinating seed:

 

Analysis:

 final results

These pumpkin seeds germinated quickly in warm weather. The length, width and fatness all changed.

Step 1: Get a piece of graph paper. Label the x-axis (horizontal) 0 to 7 for the days.

Step 2: Label the y-axis (vertical) 0 on up for the millimeters

Step 3: Use different colors for each seed and mark the measurements for each seed for each day. This means each seed has three marks, for height, for width and for fatness.

Step 4: Connect each line of dots for each seed’s measurements

 

Conclusions:

Why does the seed swell up?

 

Does the seed keep swelling the entire time? Why do you think it does this?

 

Do the height, width and fatness all change? Why do you think this is true?

 

Where does the radicle [baby root] come out? Why would it come out here? (Think back to Investigation 2.)

 

How is the seed edge different where the radicle comes out?

 

Why do you think the root comes out first?