It is the three elements of plant nutrition.

(1) Criteria for determining essential elements for plant growth and development (proposed by Arnon and Stout in 1939);

First, without some nutrients, plants cannot complete their life cycle;

Second, if a certain nutrient element is lacking, the plant presents a specific element deficiency disease, and other nutrient elements cannot replace its function, and the symptoms can be alleviated or disappeared after supplementation;

Third, it directly participates in plant metabolism in plant nutrition, not because of its indirect effect on improving plant living conditions.

When an element meets these three criteria, it is called an essential nutrient element.

(2) beneficial elements of plant growth and development.

(1) The nutrient element that constitutes plant structural matter and life matter, namely C.

H

O

ordinary

s .

②P

B

silicon (Si)

They have similar characteristics and are absorbed in the form of inorganic anions or acids. In plant cells, they either exist in the above inorganic form or combine with alcohols to form esters.

③K

natrium

calcium (Ca)

magnesium

manganese

And Cl are absorbed by plants from soil solution in the form of ions, and they only exist in juice in the form of ions in plant cells, or are adsorbed on non-diffused organic anions.

④ Iron

copper

zinc (Zn)

Molybdenum (nickel) mainly exists in plants in the form of chelation.

(3) Nitrogen, phosphorus and potassium are called the three elements of plant nutrition (i.e. fertilizer or nitrogen, phosphorus and potassium).