Measuring plant health from space SIF Solar induced

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Measuring plant health from space SIF – Solar induced fluorescence

Measuring plant health from space SIF – Solar induced fluorescence

To understand how we can measure plant health from space we need to know

To understand how we can measure plant health from space we need to know about: Photosynthesis Chloroplasts and chlorophyll The process of photosynthesis Factors affecting the rate of photosynthesis Fluorescence

Photosynthesis • Plants capture the energy from sunlight • They use this energy to

Photosynthesis • Plants capture the energy from sunlight • They use this energy to make glucose • We summarise the process of photosynthesis in the chemical equation Carbon dioxide + water energy from sunlight glucose + oxygen 6 CO 2 6 H 2 O chlorophyll C 6 H 12 O 6 6 O 2 In cells there is not just one reaction but lots that occur in a series of steps. The glucose can then be made into other molecules including the carbohydrates starch and cellulose, as well as fats and proteins. • Photosynthesis takes place in chloroplasts

Chloroplasts and chlorophyll • Chloroplasts contain the green pigment chlorophyll • Chlorophyll absorbs the

Chloroplasts and chlorophyll • Chloroplasts contain the green pigment chlorophyll • Chlorophyll absorbs the energy from sunlight • The energy is used to split water into hydrogen and oxygen atoms • The hydrogen combines with carbon dioxide from the air to make glucose • The oxygen is released as a waste product, passing out of the plant into the air

Rate of photosynthesis • In optimum conditions for photosynthesis healthy plants will photosynthesise at

Rate of photosynthesis • In optimum conditions for photosynthesis healthy plants will photosynthesise at their fastest rate, making glucose at their fastest rate. • A plant where the temperature, light intensity, or carbon dioxide level is low will have limited rate of photosynthesis and will make glucose at a lower rate.

Rate of photosynthesis • Increasing the light intensity will increase the rate of photosynthesis

Rate of photosynthesis • Increasing the light intensity will increase the rate of photosynthesis up to a point • At this point, where increasing the light does not effect the rate of photosynthesis, another factor is limiting photosynthesis i. e. the plant does not have enough carbon dioxide, water or chlorophyll to use the extra light

Unhealthy plants and photosynthesis • The rate of photosynthesis is an indicator of plant

Unhealthy plants and photosynthesis • The rate of photosynthesis is an indicator of plant health • An unhealthy plant will have a lower rate of photosynthesis • For example, if a plant’s leaves are going yellow, photosynthesis will be limited by the amount of chlorophyll available.

Fluorescence • When light is absorbed by chlorophyll some of the light is re-emitted,

Fluorescence • When light is absorbed by chlorophyll some of the light is re-emitted, this is fluorescence. • Healthy plants are photosynthesising, absorbing and then re-emitting lots of light so there is more fluorescence. • Unhealthy plants are not photosynthesising as much so absorb and re-emit less light • Maps of the fluorescence give scientists a indication of plant health.