By Alka Singh
We all must have observed that leaves change their colour during fall (the season after summer and
before winter, also known as autumn). This change in colour is usually seen in the autumn season.
Come autumn, the landscape becomes vibrant as the leaves flaunt different shades of yellow,
orange, red, etc. Let’s understand the reason behind it.
The green colour of the leaves is due to the presence of a chemical pigment called chlorophyll. The
job of chlorophyll is to trap the sunlight from the surrounding. The trapped sunlight is used by the
plant to synthesize its food by the process of photosynthesis (process by which plants make their
own food). Hence chlorophyll plays a very important role by providing nutrients to the plant which
helps in keeping it healthy, strong, and disease free.
The leaves not only have chlorophyll pigment but have other colourful pigments like- red, yellow
brown, orange etc.
During summer season, there is no dearth of sunlight present in our surroundings – so, chlorophyll
can absorb plenty of sunlight. Due to this, we don’t see any other colour on the leaves except green.
However, in autumn, the sun is farther from the earth, hence the sunlight is not warm enough. As a
result, chlorophyll is unable to trap the sunlight efficiently to make food. So, the plants break down
chlorophyll into simpler molecules to obtain energy for their survival. Now due to the breakdown of
chlorophyll pigment for plant nutrition, the other colours in the leaf start to express themselves.
Therefore, the leaves exhibit different shades of yellow, orange, brown and red.
Why do the leaves fall off?
Chlorophyll is not automatically generated by the leaf. Once a leaf loses its chlorophyll, it cannot perform the basic function of a leaf – production of food.
This is why leaves are shed, so that the plant might generate new leaves.