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,
Photosynthesis chlorophyll fluorometers. Actual plants' photosynthetic efficiency varies with the frequency of the light being converted, light intensity, temperature and proportion of carbon dioxide in the atmosphere, and can vary from 0.1% to 8%. By comparison, solar panels convert light into electric energy at an efficiency of approximately 6–20% for mass-produced panels, and above 40% in laboratory devices. The efficiency of both light and dark reactions can be measured but the relationship between the two can be complex. For example, the ATP and NADPH energy molecules, created by the light reaction, can be used for carbon fixation or for photorespiration in