Question

Who gave the criteria of essentiality?
(A) R. Hill
(B) F. F. Blackman
(C) M. P Kaushik
(D) D. L. Arnon

Answer 1

Hint: D. L. Arnon considered 16 elements essential for plant nutrition.

Complete answer: A mineral element is considered as essential based on the criteria of essentiality given by Arnon (Criteria of essentiality given by Arnon (Criteria of essentiality of inorganic micronutrients for plants.
1. These mineral nutrients are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, zinc, copper, boron, molybdenum, and chlorine.
2. The mineral nutrient elements play essential roles such as constituent of cell structures and cell metabolites, in cell osmotic relations and turgor-related processes, energy transfer reactions, enzyme-catalyzed reactions, and plant reproduction.
3. Plant productivity depends on the efficient discharge of these functions.
4. Heavy metals pollution is continuously increasing and posing threats to our environment. This heavy metals’ presence in soils accumulates in plants that become part of the food supply.
5. Essential elements are divided into two broad categories, based on the quantity in which they are by plants: Macro-elements and micro-element.
6. A plant cannot complete its life-cycle in the absence of the element. The action of the element must be specific, with no other element being able to completely substitute for it.
7. The element along can correct the disorders caused by its absence or deficiency.
8. Hence, it is clear that an element indirectly involved in plant metabolism does not fit into the criterion for the essentiality of an element.

Note: Most of the soil usually contain sufficient amounts of essential mineral elements for better crop production. These elements are required to be supplemented externally by adding the appropriate Fertilizers. Moreover, constant agricultural cultivation in the field may also cause depletion of certain elements that must be replenished in order to improve the fertility of the soil.