Why do leaves change colors during fall?
The length of the day decreases in fall and there are many changes in temperature. As mentioned above, chlorophyll pigments are produced in presence of light. Less chlorophyll is produced in autumn season as the days are shorter. The rate of decomposition of chlorophyll remains the same, but rate of production of chlorophyll decreases. This leads to ‘fading off’ of the green leaves. Carotenoids present in the leaves do not decompose as quickly as the chlorophyll molecules, as they are more stable. Also, carotenoid production does not depend on light. Therefore, number of carotenoid molecules increase as chlorophyll decreases. This leads to leaves changing color into yellow or orange and sometimes even red. Anthocyanin is another color pigment present in the leaves. If leaves contain anthocyanin, with the decrease in chlorophyll molecules, the colors developed will be due to this pigment. Thus, leaves changing color into red or purple is due to high amount of anthocyanin. If carotenoids
