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Investigate the effect of light intensity on the growth of newly germinated seedlings

In this practical you will investigate the effects of light intensity on the growth of newly germinated seedlings. To record results, you can measure the length of the shoots and create labelled biological drawings to illustrate the effect of light intensity on the growth of the seedlings.

Germination is the beginning of plant growth, and the plant will continue to grow if the correct conditions are available.

Plant seeds that can be used for investigation are mustard or cress.

The independent variable for the investigation is light intensity.

One group of seeds are placed in the dark, one group in the light and one group in partial light. This will show the effect of light intensity on the germination and growth of the seedlings.

Method

1. Put cotton wool into three petri dishes, and add the same volume of water to each dish.
2. Add ten seeds to each dish and place them in a warm place where they won't be disturbed.
3. Allow the seeds to germinate, and add more water if the cotton wool dries out.
4. Once the seeds have germinated, ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary.
5. One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light.
6. Every day for one week, measure the height of each seedling and record the results in a table. You must record the height of the individual seedlings on each day.
7. Calculate the mean of the seedlings each day, and compare the mean heights in the three different locations.