What is an essential nutrient?
*First, it is an inorganic nutrient. This is what distinguishes plants from animals (and some
microorganisms) that require organic foodstuffs.
*Arnon and Stout proposed 3 criteria for essentiality in 1939. They are:
*Deficiency of the element makes it impossible for the plant to complete its life cycle
*Deficiency is specific for the element in question – it cannot be replaced by another element in the
plant life cycle
*The element is directly involved in the metabolism of the plant – it is a constituent of an essential
metabolite or is required for the action of an enzyme system