How to understand the relationship between elements and plants

Phytonutrients

The nutrients required for normal growth and development of plants are divided into essential elements and beneficial elements; essential elements are divided into macroelements (also called macroelements) and trace elements.
Essential elements refer to plant nutrients that are necessary for normal plant growth and development and cannot be replaced by other elements. According to the amount required by plants, essential elements are divided into essential macroelements and essential trace elements.
Essential macroelements include carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulfur (S), potassium (K), magnesium (Mg), calcium (Ca), silicon (Si) (The latest plant physiology says that Si is a newly added macro-element)
The essential trace elements are iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), chlorine (Cl), sodium (Na), and nickel (Ni) (latest According to plant physiology, Na and Ni are newly added trace elements).

Introduction

Although macroelements and trace elements are different in required amounts, they both have important functions for the life activities of plants and are indispensable.
The physiological functions of essential elements can be summarized as: components that constitute the organic structure of plants and participate in enzymatic reactions or energy metabolism and physiological regulation. For example, cellulose, monosaccharides and polysaccharides contain carbon, hydrogen, and oxygen; proteins contain carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur; some enzymes contain iron or zinc; Mg2+ and K+ are two different enzymes. Activators; K+ and Cl- play an important role in osmoregulation, etc.
Beneficial elements refer to elements that are necessary for normal growth and development of some plants but not for all plants. Such as cobalt, etc.
Silicon is necessary for gramineous plants such as rice, wheat, and sugarcane, and it also has a certain effect on tomatoes, cucumbers, beans, strawberries, etc. Silicon deficiency will weaken the fertilization ability of plants during the reproductive growth period and reduce fruit number and fruit weight.
Cobalt is necessary for nitrogen fixation and root nodule growth of leguminous plants; nickel plays an important role in nitrogen metabolism of leguminous plants.
In addition to promoting the growth and development of certain plants, some beneficial elements can replace part of the physiological functions of certain essential elements. For example, for some natriuretic plants (beets, etc.), Na+ can replace the role of K+ in osmoregulation and other aspects. When K+ is in short supply, Na+ can replace K+.

Physiological function

Physiological functions of major nutrients
Although plants have different requirements for various nutritional elements, various nutritional elements have different physiological functions in the life metabolism of plants, and they are equally important and irreplaceable for each other. Understanding the physiological functions of various elements is of great significance for scientific fertilization and achieving high quality and high yield.
(1) Carbon, hydrogen, oxygen
Carbon, hydrogen, and oxygen are abundant in plants, accounting for more than 90% of the dry weight of plants. They are the main components of plant organisms. They are represented by various carbohydrates, such as cellulose, hemicellulose, and pectin. It exists in form and is a component of the cell wall. They can also constitute active substances in plants, such as certain cellulose and plant hormones. They are also components of sugar, fat, and acid compounds.
In addition, hydrogen and oxygen also play an important role in the biological redox process in plants. Since carbon, hydrogen, and oxygen mainly come from carbon dioxide and water in the air, the application of fertilizers is generally not considered. However, plastic greenhouses and greenhouses should consider applying CO2 fertilizer, but it should be noted that the concentration of CO2 should be controlled below 0.1%.
(2) Nitrogen
Nitrogen is a component of many important organic compounds in plants and affects the metabolic processes, growth and development of plants in many ways. Nitrogen is the main component of protein, the basic substance in the protoplasm composition of plant cells, and the basis of plant life activities. Without nitrogen there would be no life. Nitrogen is a component of chlorophyll and nucleic acids. Various biological enzymes in plants also contain nitrogen. In addition, nitrogen is also a component of some vitamins (such as vitamin B1, B2, B6, etc.) and alkaloids (such as nicotine, theophylline).
(3) Phosphorus
Phosphorus is a component of many organic compounds in plants. It participates in various metabolic processes in plants in various ways and plays an important role in plant growth and development. Phosphorus is the main component of nucleic acids. Nucleic acids exist in cell nuclei and protoplasm. They are extremely important in plant growth, development and metabolic processes and are indispensable for cell division and root growth.
Phosphorus is a component element of phospholipids and an important component of biological membranes. Phosphorus is also a component of other important phosphorus compounds, such as adenotriphosphate (ATP), various dehydrogenases, aminotransferases, etc. Phosphorus improves plants' stress resistance and ability to adapt to external environmental conditions.
(4) Potassium
Potassium is not a component of organic compounds in plants. It mainly exists in the ionic state in plant cell fluids. It is an activator of various enzymes and plays an important role in the metabolic process. It not only promotes photosynthesis, but also promotes nitrogen metabolism and improves plants' absorption and utilization of nitrogen. Potassium regulates the osmotic pressure of cells, regulates plant growth and economic water use, and enhances plants' ability to resist adverse factors (drought, cold, disease, salt-alkali, lodging). Potassium can also improve the quality of agricultural products.
(5) Calcium, magnesium, sulfur
Calcium can stabilize the biofilm structure, maintain cell integrity, and plays an important role in plant ion selective absorption, growth, senescence, information transmission, and plant stress resistance.
Magnesium is a component of chlorophyll. Both chlorophyll a and chlorophyll b contain magnesium, which is of great significance to photosynthesis, carbohydrate metabolism and respiration of plants.
Sulfur is an indispensable component of proteins and enzymes.
(6) Trace elements
Iron is necessary for the synthesis of chlorophyll and is closely related to photosynthesis.
Boron can promote the normal operation of carbohydrates, promote the formation and development of reproductive organs, promote cell division and cell elongation, and improve the nitrogen-fixing ability of leguminous plants.
The role of manganese in plants is mainly achieved through its influence on enzyme activity, so manganese is also called a catalytic element.
Copper is a component of many oxidases in plants, or an activator of certain enzymes. It participates in many redox reactions. It also participates in photosynthesis, affects nitrogen metabolism, and promotes the development of flower organs.
Zinc is a component or activator of certain enzymes. Through the action of enzymes, zinc has a wide range of effects on plant carbon and nitrogen metabolism, participates in photosynthesis, participates in the synthesis of auxin, promotes the development of reproductive organs and improves stress resistance.
Molybdenum is a component of nitrogenase and nitrate reductase. Molybdenum is indispensable for nitrogen metabolism and symbiotic nitrogen fixation of leguminous plants. Molybdenum can also promote photosynthesis.
Chlorine participates in plant photosynthesis, regulates the opening and closing of stomata, and enhances the ability of crops to suppress certain diseases.