Effect of Light on Seeds

It would have been impossible to live for us without plants and trees, don't you think so? The green plants we see around us are the main source of food and nutrients for us humans as well as for many animals. Many plants are grown as food products. We use the fruits, leaves, seeds or roots of such plants as foods. When consumed, these provide us with nourishment and help us to grow up into big and strong individuals.

But what do the plants need for their growth?
When young, the plants remain within their seeds as we humans reside inside our mother's body. As we come out of our mother's womb after maturing, so also the plants come out of their seeds on getting some favourable environmental conditions that help them to grow up. These conditions are :

Water,
Oxygen,
Temperature and
Sunlight.

Sunlight is one of the most important factors that help a seed to sprout into a plant. Most seeds are not affected by light or darkness, but many seeds, including species found in forest settings will not germinate until an opening in the canopy allows them to receive sufficient light for the growing seedling.

By trying out a simple experiment, you can have a first hand experience of how the brightness of light can affect the germination and the growth rate of a seed.

What you need:
1) Greenhouse or sunny window sill,
2) 10 bean seeds,
3) 10 small pots,
4) Water,
5) Potting soil(moistened),
6) Ruler and
7) Pencil.

What to do:

1) Fill the 10 small pots with equal amounts of moist potting soil.

2) Using the pencil, make holes about 2 centimeters deep in each pot.

3) Place one bean seed in each pot, and cover the seeds with some of the soil.

4) Place 5 of the pots in the greenhouse or on a window sill on the sunny side of the house. Name this set of pots as GROUP-A. Place the other 5 on a window sill that does not receive bright sunlight. Name this set of pots as GROUP-B.

5) Generally seeds germinate within 7 days. Once the seeds come out of the soil, begin taking the stem measurements. Take stem measurements for 14 days.

Make sure that the temperature and oxygen supply for each set remain constant. Water the plants as needed and see that the amount of water you provide each plant with remains equal. Unless the other factors remain constant, how can you figure out what effect light has on the seeds?

Note the difference in stem length for each set of plants, and write down your observations. Write about all the differences (color of leaves, length of stems, etc.) that you found between seedlings that grew in the bright sunlight compared to less bright light and the reasons you think to be the causes of those differences.

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