Who gave the criteria of essentiality of elements?

Solution (By Examveda Team)

D. L. Arnon gave the criteria for the essentiality of elements.
The term essential mineral element (or mineral nutrient) was proposed by Arnon and Stout (1939). They concluded three criteria must be met for an element to be considered essential.
The element must be directly involved in plant metabolism. These criteria are important guidelines for plant nutrition but exclude beneficial mineral elements. Beneficial elements are those that can compensate for the toxic effects of other elements or may replace mineral nutrients in some other less specific function such as the maintenance of osmotic pressure.