文档介绍：Chapter 1
Essential elements
Plant nutrition is a term that takes into account the interrelationships of mineral elements in the growth medium as well as their role in plant growth.
Concept of plant nutrition
Concept of plant nutrition
Complex interactions involving weathering(风化) of rock minerals, decaying(腐解) anic matter, such as humus and residues of plant ,animals, and microbes, take place to form anic minerals in soil.
Roots absorb mineral nutrients as ions in soil water. Many factors influence nutrient uptake for plants.
This interrelationship involves plex balance of mineral elements essential and beneficial for optimum plant growth.
Concept of plant nutrition
Essential elements
The material of living plants consist anic matter, water and minerals. The percentage distribution of these ponents is in the following order of magnitude:
Water 70%(fresh matter)
Organic material 27%(fresh matter)
Minerals 3% (fresh matter)
The term essential mineral element (or mineral nutrient) was proposed by Arnon and Stout (1939).
They concluded three criteria(标准) must be met for an element to be considered essential(必需的).
Essential elements
Three criteria of Essential elements
1. A plant must be unable plete its life cycle in the absence of the mineral element.
2. The function of the element must not be replaceable by another mineral element. or deficiency symptoms can not be remedied by supplying some other element
3. The element must be directly involved in plant metabolism.
Sixteen Essential Elements
Carbon (C) Hydrogen (H) Oxygen (O)
Nitrogen (N) Phosphorus (P) Potassium (K)
Calcium (Ca) Magnesium (Mg) Sulfur (S)
Iron (Fe) Manganese (Mn) Copper (Cu)
Zinc (Zn) Molybdenum (Mo) Boron (B)
Chlorine (Cl)
position of Plants
Relative amounts of essential elements in plant tissues