西北农林科技大学：《植物营养学》课程教学资源（PPT课件讲稿，英文版）Chapter 14 Micronutrient elements

Chapter 14 Micronutrient elements General Characteristics

Micronutrient elements Chapter 14 General Characteristics

Micronutrients in Soils and Crops Nutrient Soil Content(kg/ha) Corn Removal (kg/ha) Boron (B) 22-225 0.07 Copper (Cu) 2-450 0.06 Iron(Fe) 11,200-224,000 0.12 Manganese(Mn) 112-11.200 0.09 Molybdenum (Mo) 1-8 0.03 inc(Zn) 22-675 0.17

Nutrient Soil Content (kg/ha) Corn Removal (kg/ha) Boron (B) 22-225 0.07 Copper (Cu) 2-450 0.06 Iron (Fe) 11,200 – 224,000 0.12 Manganese (Mn) 112-11,200 0.09 Molybdenum (Mo) 1-8 0.03 Zinc (Zn) 22-675 0.17 Micronutrients in Soils and Crops

General Characteristics A. Micronutrients are required by all plants but in smaller amounts compared to the macronutrients Deficiencies of micronutrients can reduce growth just as much as deficiencies of macronutrients Remember the“ Law of the minimum

• A. Micronutrients are required by all plants but in smaller amounts compared to the macronutrients. • Deficiencies of micronutrients can reduce growth just as much as deficiencies of macronutrients. Remember the “Law of the Minimum”. General Characteristics

General Characteristics b The amount of micronutrient that is needed by the plant can have a narrow ange. If the amount of micronutrient is too high, it is possible for toxicity to occur Available forms 1. Cations: Fe2+ Fe3+. Mn2+ Zn2+ Cu2+ 2. Anions: MoO42, Ch- 3. Neutral: H3 BO3

B The amount of micronutrient that is needed by the plant can have a narrow range. If the amount of micronutrient is too high, it is possible for toxicity to occur. Available forms 1. Cations: Fe2+, Fe3+, Mn2+, Zn2+, Cu2+ 2. Anions: MoO4 2- , Cl- 3. Neutral: H3BO3 General Characteristics

Micronutrient function in plants 1. Enzymes and coenzymes a) Structural component of enzymes b) Involved in the activation and regulation of enzymes Oxidation and reduction reactions Micronutrients are involved in electron transport

Micronutrient function in plants 1. Enzymes and coenzymes a) Structural component of enzymes b) Involved in the activation and regulation of enzymes 2. Oxidation and reduction reactions Micronutrients are involved in electron transport

Micronutrient transformations in the soil 1. The transformations that micronutrients undergo in the soil vary depending on the nutrient, but overall the reactions are similar to what has already been discussed for macronutrients a)Mineralization and immobilization b) Adsorption and desorption to clay or organic matter surfaces c)Precipitation and dissolution of secondary minerals

Micronutrient transformations in the soil 1. The transformations that micronutrients undergo in the soil vary depending on the nutrient, but overall, the reactions are similar to what has already been discussed for macronutrients. a) Mineralization and immobilization b) Adsorption and desorption to clay or organic matter surfaces c) Precipitation and dissolution of secondary minerals

Micronutrient transformations in the soil 2. Micronutrients undergo one transformation that is quite different from the transformations that we discussed for the macronutrients That transformation is called chelation

Micronutrient transformations in the soil 2. Micronutrients undergo one transformation that is quite different from the transformations that we discussed for the macronutrients. That transformation is called chelation

The chelation process in the soil a) The word chelate means claw. Chelation refers to the process in which organic molecules in the soil form a complex with micronutrient ions b) The chelated micronutrients are carried by mass flow and diffusion to the root surface

a) The word chelate means “claw”. Chelation refers to the process in which organic molecules in the soil form a complex with micronutrient ions. b) The chelated micronutrients are carried by mass flow and diffusion to the root surface. The chelation process in the soil

The chelation process in the soil c) The chelate is broken down in rhizosphere The micronutrient is taken up by the root and the organic molecule diffuses away. d) The organic molecule can complex with more micronutrients and the process is repeated

c) The chelate is broken down in rhizosphere . The micronutrient is taken up by the root and the organic molecule diffuses away. d) The organic molecule can complex with more micronutrients and the process is repeated. The chelation process in the soil

The chelation process in the soil e) There is still a lot about the chelation of micronutrients that is unknown. The organic molecule that forms the chelate may be derived from Natural chelates (1) Organic compounds released by the roots or soil mIcroorganIsm, such as Siderophores高铁载体and phytosiderophores植物高铁载体 (2)Compounds released during the decomposition of soil organic matter, such as fulvic acids (3)Man-made chelates: EDTA, DTPA EDDHA etc

e) There is still a lot about the chelation of micronutrients that is unknown. The organic molecule that forms the chelate may be derived from: Natural chelates (1) Organic compounds released by the roots or soil microorganism, such as Siderophores高铁载体 and phytosiderophores植物高铁载体 (2) Compounds released during the decomposition of soil organic matter ,such as fulvic acids (3) Man-made chelates: EDTA, DTPA EDDHA etc The chelation process in the soil