how-plants-dissipate-excess-sunlight-as-heat

Researchers at MIT have observed one of the possible mechanisms by which Plants are able to dissipate excess sunlight absorbed by the plants.

Photosynthesis

  1. Photosynthesis is a biological process that is life-sustaining for all green plants.
  2. In this process, light energy is converted into chemical energy, that is stored in the form of sugar molecules.
  3. The process takes place in the chloroplasts and it is done through chlorophyll, a photosynthetic pigment.
  4. It helps in the synthesis of their own nutrients. 
  5. Solar energy, water, and carbon dioxide are required for this process.
    1.  The by-product of this process is oxygen.

6CO2    + 6H2O        → C6H12O6  + 6O2

 

Source: Wikipedia Commons

 

Significance 

  • During the process, oxygen gas is released into the environment which is essential for respiration by humans, animals, and other living species.

Factors of Influence

  1. Light intensity
  2. Water
  3. Soil condition like pH
  4. Concentration of CO2
  5. Temperature and other climatic conditions 

Stages of Photosynthesis

It takes place in two stages.

  1. The first type of reaction takes place in the day time and is called Light-dependent reactions.
  2. Second type of reaction is called the light-independent reaction.
    1. It is also called a dark reaction or the Calvin cycle.

What is the research aimed at?

  1. It was known that  If sunlight is in excess, it can lead to leaves being dehydrated and damaged. And in order to prevent such damage, plants dissipate extra light as heat. 
    1. Previous research has shown how plants quickly adapt to changes in sunlight intensity. 
    2. Even in very sunny conditions, only 30 percent of available sunlight is converted into sugar, and the rest is released as heat
    3. The excess energy, if not released, leads to the creation of free radicals that can damage proteins and other important cellular molecules.
  2. So far, it had been difficult to observe the heat dissipation phenomenon, given that it occurs on a very fast time scale, in femtoseconds or quadrillionth of a second.
    1.  Also, energy transfer takes place over a broad range of energy levels.

Findings of the research

  1. The research found that excess energy is transferred from the pigment chlorophyll, which gives leaves their green color, to other pigments called carotenoids
    1. The carotenoids then release the energy as heat.

Carotenoids

Carotenoids are plant pigments responsible for bright red, yellow and orange hues in many fruits and vegetables. 

  • They also have an important antioxidant function of deactivating free radicals.
  • Animals cannot manufacture carotenoids themselves; they have to get it in their diet.
  • Carotenoids need to be consumed with fat in order for the body to absorb them. 
  1. MIT researchers developed a modification to a femtosecond spectroscopic technique, which allowed them to observe over a broader range of energy levels– spanning from red light to blue light.
    1.  Using the new technique, researchers could observe that chlorophylls absorb red light and carotenoids absorb blue and green light, thus being able to monitor energy transfer.

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Source

Image Source: The Indian Express