How do the leaves turn colors?
Three factors influence autumn leaf color: leaf pigments, length of night and weather. The timing of color change and leaf fall is primarily regulated by the calendar that is the increasing length of night. None of the other environmental influences, such as temperature, rainfall and food supply, are as unvarying as the steadily increasing length of night during autumn. As days grow shorter and nights grow longer and cooler, biochemical processes in the leaf begin to paint the landscape. That’s where pigment comes in. A color palette needs pigments, and there are three types that are involved in autumn color: • Chlorophyll, which gives leaves their basic green color. It is necessary for photosynthesis, the chemical reaction that enables plants to use sunlight to manufacture sugars for food. Trees in the temperate zones store these sugars for the winter dormant period. • Carotenoids, which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils, as well a
