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?
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
A dark closet or box, a refrigerator [ask first], a warm, light counter
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.
Write down how long each sprout is in the table and what it looks like in your notes.
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.]