Question

Who discovered the phenomenon of red drop? In which part of the visible spectrum does this phenomenon occur?

Answer 1

Wavelengths beyond 700nm are apparently of insufficient energy to drive any part of photosynthesis. So a huge drop in efficiency has been noticed at 700nm. This phenomenon is called as RED DROP EFFECT. In other words, there is a sharp decrease in quantum yield at wavelengths greater than 680nm. So, this appears in the visible range spectrum and corresponds to the red light (630-700nm) and hence the name. It is called Emerson effect after the discoverer and is said to increase in the rate of photosynthesis after chloroplasts are exposed to the light of wavelength 680 nm (deep red spectrum) and more than 680 nm (far red spectrum).