February 03, 2025 2 min read
There is a common misconception that plants do not use green light for photosynthesis.
This error is the result of misinterpretation of data from chlorophyll absorption spectrum diagrams. Many popular textbooks make the same mistake, although some have corrected it in their updated versions. (See figure below). It was once thought that chlorophyll only absorbs red/blue light and reflects green light, and therefore plants do not use green light for photosynthesis. Such older spectral charts were constructed by shining light through extracted chlorophyll pigments in laboratory petri dishes and observing what spectrum of light passed through unabsorbed. However, such laboratory conditions do not accurately replicate the process of photosynthesis in living leaves.
It is now known that leaves contain other pigments that use green light for photosynthesis, and that - depending on the 3D orientation and structure of chlorophyll and other pigments - a much wider spectrum of light is absorbed by leaves than previously thought.
All visible light is used for photosynthesis in a living leaf. Red and blue spectra are more efficient at stimulating photosynthesis. However, as red/blue light saturation increases, the efficiency of green light in stimulating photosynthesis eventually overtakes that of red/blue light. This means that the efficiency of the light spectrum on photosynthesis is not linear. This is explained in more detailed papers such as the one below:
The insightful scientific paper that examines the role of green light in plant photosynthesis is "Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light": Revisiting the Enigmatic Question of Why Leaves are Green" published by the University of Tokyo. (excerpt below)
Read more in-depth on the full paper here.