The hypothesis of photosynthesis based on two pigment systems was suggested by_________.

The correct answer is: Emerson

• Emerson and Arnold described the two pigment system of photosynthesis
• The hypothesis describes that upon exposure of the plants to light of around 670 and 700 nm, the rate of photosynthesis increased
• The red and blue light pigments are important for photosynthesis which are respective of the wavelengths mentioned 

The Emerson effect is the increase in rate of photosynthesis after exposure to light of wavelength 670 nm far red light and 700 nm, red light respectively. When simultaneously exposed to light of both wavelengths, the rate of photosynthesis is far higher than the sum of red light and far red light photosynthesis rates. The effect was early evidence, that photosystems processing different wavelengths cooperate in photosynthesis.