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Absorption curves of chlorophyll a/b and carotenoids
Why are leaves mostly green in summer and gold-yellowish in fall? Answer: there is much chlorophyll and carotene in the leaves in summer. These molecules absorb blue and red light and reflect green-yellow light. What you perceive is the greenish reflected light. In fall, the temperature drops and chlorophyll gradually decays, while the more stable, yellow, orange and reddish carotene pigments persist and dominate the color palette. Besides, the production of (red) anthocyanes in the vacuoles of the foliar cells rises.