Who proposed the criteria of essentiality of plant nutrients?

Solution (By Examveda Team)

D. I. Arnor and Stout proposed the criteria of essentiality of plant nutrients in 1939. The elements that are considered essential elements in deficiency of which the plant must be unable to complete its life cycle.
There are 17 elements classified as essential elements and these are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, Sulphur, calcium, magnesium, boron, chlorine, copper, iron, manganese, molybdenum, nickel and zinc.