Depth of Sowing Activity Part B
What's the difference?

[ Review Part A ]

Plants come in many different shapes and sizes, and have different growing habits. These differences can affect how well the plants survive under different conditions.

When plants emerge from the ground the first pair of leaves can look very different from the rest.

These different looking leaves are called "seed leaves" or "cotyledons" - the delicious round looking bits of Chelsea Chickpea will become her seed leaves when she germinates.

Now some plants poke their cotyledons through the soil before any other leaves come up, but other plants leave their cotyledons buried below the ground.

Does this effect the plants survival in any way? Let's do the activity and see.

Materials Needed

Each group of students will need:

• Lupin and Chickpea seedlings that have been growing for at least 2 weeks
• Scissors for cutting off plant tops

What to Do Chop the tops of your lupin and chickpea seedlings off with your scissors (you can pretend you're a sheep, kangaroo or rabbit that's got into the farmers paddock, or a hail storm that's broken the tops off the plants.) Keep the pots in a warm sunny spot and water as needed for another 2-3 weeks. Check the pots every day for 2- 3 weeks and record your observations. Some ideas on what you could record are given in the next section.

What to Record

Start with a "brainstorming" session. What observations could you make? How could you record them?

Suggested Recording Sheet (but of course you can think of a better one yourself):

Record regrowth of lupins and chickpeas after cutting. Record height of plants in cm or mm. (Your pots will contain up to 4 plants each. Will you record the height of each plant? Will you just measure the tallest plant in each pot, the shortest plant or work out the average height of plants in each pot? Discuss the advantages and disadvantages of doing these things.)

Thought Questions

You are Farmer Jones and you're very keen to keep up with all the latest developments in farming. You're off to spend time at some important Field Days. While you are away some unknown person leaves the gate to the lupin paddock open. The sheep now get in and have two lovely days nipping the tops off the luscious lupin crop.

• Draw a picture or write a sentence to describe how you feel when you discover this.
• Write a sentence to explain why you feel this way.
• Would you feel the same way if the sheep had done the same to the chickpea crop? Why or why not?

Some Explanations

When lupins emerge from the ground, their cotyledons or seed leaves appear above the ground.

When chickpeas emerge, their seed leaves remain buried in the ground.

Close to the seed leaves is a part of the plant that new stems grow. Lupins have this part of the plant above the ground, but chickpeas keep it below the ground. This means that if lupin tops are cut or eaten off, no new tops grow. If chickpea tops are cut or eaten off, new stems will grow from the bit that is protected below the ground.

[ Review Part A ]