What do you understand by Emerson effect ? How does it observed?

cbse
photosynthesis

#1

“The fall in photosynthetic yield beyond red region of the spectrum is called Emerson’s first effect or red drop.”
Emerson et. al. (1957) exposed unicellular alga Chlorella to monochromatic light and measured the photosynthetic yield in terms of quantum yield. They observed that the quantum yield of photosynthesis decreased very sharply towards far red region of the spectrum.