Question
Why is the colour of a leaf kept in the dark frequently yellow, or pale green? Which pigment do you think is more stable?
Solution
The production of the chlorophyll pigment essential for photosynthesis is directly proportional to the amount of light available. In the absence of light, the production of chlorophyll-a molecules stops and degrades slowly. This changes the colour of the leaf gradually to light green. The xanthophyll and carotenoid pigments become predominant as they are not degraded, causing the leaf to become yellow. These pigments are more stable as light is not essential for their production.
