Emerson effect
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The Emerson effect is the increase in the rate of photosynthesis after chloroplasts are exposed to light of wavelength less than 680 nm (deep red spectrum) and more than 680 nm (far red spectrum). When simultaneously exposed to light of both wavelengths, the rate of photosynthesis is higher than the sum of the red light and far red light photosynthesis rates. The effect was early evidence that two photosystems, processing different wavelengths, cooperate in photosynthesis.[1]
Robert Emerson described the eponymous effect in 1957.[2] In his paper he observed that:
- When plants are exposed to light having wavelength greater than 680 nm, then only one photosystem is activated; i.e. PS700 resulting in formation of ATP only.
- When plants are exposed to light having wavelength less than 680 nm, the rate of photosynthesis was very low.
- On giving both shorter and higher wavelengths of light, the efficiency of the process increased, because both photosystems were working together at the same time, resulting in higher yield.
