Orange (colour) and absorb mostly greenish-blue light. (See also shades of orange). Other orange pigments include: The orange colour of carrots, pumpkins, sweet potatoes, oranges, and many other fruits and vegetables comes from carotenes, a type of photosynthetic pigment. These pigments convert the light energy that the plants absorb from the sun into chemical energy for the plants' growth. The carotenes themselves take their name from the carrot. Autumn leaves also get their orange colour from carotenes. When the weather turns cold and production of green chlorophyll stops, the orange colour remains. Before the 18th century, carrots from Asia were usually purple,
Non-photochemical quenching Non-photochemical quenching Non-photochemical quenching (NPQ) is a mechanism employed by plants and algae to protect themselves from the adverse effects of high light intensity. It involves the quenching of singlet excited state chlorophylls (Chl) via enhanced internal conversion to the ground state (non-radiative decay), thus harmlessly dissipating excess excitation energy as heat through molecular vibrations. NPQ occurs in almost all photosynthetic eukaryotes (algae and plants), and helps to regulate and protect photosynthesis in environments where light energy absorption exceeds the capacity for light utilization in photosynthesis. When a molecule of chlorophyll absorbs light it is promoted from its ground state