Plant Growth Experiments Concerning Light
Plants need light to produce energy, grow and survive. Several key experiments increased knowledge in this area. Does this Spark an idea?
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Phototropism
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The tendency of plants to grow toward a sunny window, called phototropism, was first explained as plants detecting and growing towards air currents, not light. In the 18th century, Abbe Tessier tested this idea by placing plants between a sunny window that didn't admit any air and an opening through which air flowed freely. Plants grew toward the window, showing that they grew toward light, not air.
Darwin Experiments
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In 1880, Charles and Francis Darwin demonstrated that the rapidly growing tips of plants detected light and caused plants to grow in a certain direction. When they covered the tips of plants with foil, the plants didn't exhibit phototropism. When they buried all but the tips of the plants in sand, the tips nonetheless continued growing toward the light.
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Seed Germination
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An easy home experiment shows the importance of light to plants. Grow two sets of seeds, one in the dark and one in the light. While germination occurs normally in both sets, the dark-grown seedlings become long and thin until they topple. Their leaves won't open or turn green as the light-grown seedlings do.
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References
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