In 1985, researchers at Cornell University study the dying process in leaves, after exposing leaf surfaces to light bursts, herbicides and chemicals common in air pollution.
Turning Over a New Leaf: How Leaves Die
JANE PAULEY, anchor:
This morning science correspondent Robert Bazell is here with a report on a scientist who studies leaves.
ROBERT BAZELL, reporting:
Morning Jane. We try to cover all aspects of science in these weekly reports, but one area I think we haven’t paid enough attention to is plant science. We depend on plants for a lot of things. In Ithaca, New York, there is a researcher who has invented a device to study leaves. And what he is finding has important scientific and commercial applications. The appearance of the leaves of autumn is one of nature’s greatest spectacles. The leaves turn different colors because they are dying as the trees prepare for winter. In the spring there will be new green leaves. But as the leaves of trees or other plants begin to lose their green when it is not part of nature’s renewal, it means the plant is in trouble. At the Boyce Thompson Institute at Cornell University, James Ellinson studies the stresses that can kill leaves. And he also studies what goes on inside the leaf as it dies. He uses kidney bean plants for many of the experiments. He places the leaves inside a device, which measures the amount of light the plant absorbs. A strobe light flashes at the leaf, and a camera lens records how much light is given off. If the plant is healthy, it absorbs the light for photosynthesis, the process in which plants convert light energy to food. If the plant is in trouble, the light is simply reflected. Ellinson can tell specifically where the damage is. Here he paints an herbicide on the plant in a specific pattern, and as where the leaf dies.
DR. JAMES ELLINSON (Cornell University): What I’m trying to do is something that plant sciences, scientists have a hard time doing for a long time. And that is to determine how a plant responds to different environmental and chemical stresses, without having to tear the plant apart to look at its insides.
BAZELL: One of his major efforts is to study the effects of pollution. He can give the leaf a dose of sulfur dioxide, one of the major components of air pollution. Here the top part of the leaf is exposed to the pollutant and begins to die. If the exposure is too long, the damage is permanent. But if it is short enough, it is reversible. One of the goals of the research is to make plants that can resist the damage.
DR. ELLINSON: If we’re able to understand how these plants alter their ability to photosynthesize, then eventually we should be able to alter the plants themselves through new genetic manipulation methods to produce new types of plants that are better suited to hostile environments in which we might ask the plants to grow.
BAZELL: If such a goal could be accomplished, falling leaves would mean the end of summer, but nothing more.
Organisms need energy to survive. Some organisms are capable of absorbing energy from sunlight and using it to produce sugar and other organic compounds such as lipids and proteins.
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