1. Monitoring Crop Status

Factors affecting crop spectral signatures

Plants have a particular way to reflect the electromagnetic radiation. This unique characteristic is known as the vegetation's spectral signature. Reflectance of vegetation is very low in the blue and red regions of the electromagnetic spectrum, slightly higher in the green region and high in the near infra-red. For more information on the vegetation spectral signature, see this page.

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Loss of chlorophyll
Loss of chlorophyll in a leaf (chlorosis).
Source: Wikimedia Commons

The normal growth process of a plant can be disrupted when it goes through a stress period. When in stress, the plant is not functioning properly because of one or more causes. When a plant is stressed, it usually expresses certain visible symptoms, but also some that are not visible to the human eye. Stress symptoms may appear in all of the plants of the field or in some portions of the field, depending on the cause.

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Loss of chlorophyll
Development of a fungus (Uncinula necator - commonly known as powdery mildew) on a melon plant.
Source: Wikimedia Commons

Stress is caused by a number of external factors. Can you think of any?

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Example