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is the study of the functions and dynamics of nutrients in plants, soils and ecosystems as well as of plant production processes.

Plant nutrition

Investigates how the organic-matter and mineral content of the local environment affects the nutritional status of plants, and the organisms — including humans — that feed on them.

Plant nutrition

Contains an adequate supply of all the nutrients required for plant growth.

fertile soil

What defines a “fertile soil” is determined by the combination of:

physical , physiochemical properties

refers to the capacity of the soil to provide adequate amounts of water, oxygen and plant nutrients for the optimum growth of the plant.

Soil fertility

Soil consists of these major components:

Mineral matter 45%, Air 25%, Water 25%, Organic matter 5%

• Also called humus • Made up of microorganisms (dead and alive), and dead animals and plants in varying stages of decay.

Organic matter

improves soil structure and provides plants with water and minerals

Humus

Soil particles that are 0.1 to 2 mm in diameter are .

sand

Soil particles between 0.002 and 0.1 mm are called,

silt

Even smaller particles, less than 0.002 mm in diameter, are called.

clay

Some soils have no dominant particle size and contain a mixture of sand, silt, and humus; these soils are called.

loams

Ideal soil

loamy texture

Soil fertility management has two requirements:

establishing and maintaining the soil pH and essential plant nutrient elemental content within their desired ranges for that soil type , crop or cropping sequence employed with its associated cultural management practices.

A soil has both a solid and a liquid phase. The essential plant mineral nutrient elements exist in four solid forms:

1. In minerals that are water insoluble , 2. In minerals that are slightly water soluble , 3. As ions held on the exchange sites of soil colloids , 4. As a constituent in soil organic matter

The rate at which this process occurs depends on a number of soil factors

• pH , • Soil moisture content , • Physiochemical characteristics of the colloidal substances , • Solubility characteristics of the solid-phase components , • Temperature, • Biological activity

Elements are released from the solid phase into the liquid phase, called the,

soil solution

How these ions are brought into proximity to the root occurs by means of three processes:

mass flow, diffusion, root interception

occurs when water moves within the soil mass, carrying dissolved ions along with the moving water.

Mass flow

Water movement can occur in three directions:

down through , Pulled up through , Laterally

the soil profile as a result of rainfall or applied irrigation water,

down through

The soil profile by the evaporation of water at the soil surface,

pulled up through

within the soil profile from an advancing water front.

laterally

is the process by which ions move within the soil solution from an area of high concentration to an area of lower concentration.

Diffusion

occurs as plant roots expand into the soil mass, resulting in an ever-increasing root surface contact with soil particles and their surrounding soil solution.

Root interception

The roots are the organs of a plant responsible for the following functions:

1. Anchoring the plant in the rooting medium , 2. Means for water absorption , 3. Means for essential and nonessential plant nutrient element absorption

The first developed root of a plant which is originally the radicle.

Primary Root

Roots that arise from the primary and gives rise to tertiary roots

Secondary roots

Roots that arise from the secondary roots and contains the active growing portions of the root.

Tertiary roots

What Are the Main Parts of a Plant Root System A typical plant root system shows four distinct regions or zones:

1) region of root cap, , 2) region of cell division or meristematic region , 3) region of elongation, and , 4) region of maturation or differentiation.

The tip of the root is protected by a multi-cellular (more than one cell) structure called

The Region of Root Cap

It is located a few millimeters above the root cap. The cells of the meristematic region are typically small, thin-walled, and contain dense protoplasm. contain three layers: i) Dermatogen – the outermost layer, ii) Plerome – the middle layer, and iii) Periblem – the innermost layer.

The Region of Cell Division (Meristematic Region)

Meristematic cells contain three layers:

i) Dermatogen – the outermost layer, , ii) Plerome – the middle layer,, iii) Periblem – the innermost layer.

It is located next to the meristematic region. They are incapable of cell division.

The Region of Elongation

Located next to the region of elongation, it is also called the piliferous region. They develop when the cells of the elongation zone differentiate and mature into specialized tissues such as root hairs, endodermis, and cortex.

The Region of Maturation or Differentiation

Coined by the German agronomist and physiologist Lorenz Hiltner to describe the plant-root interface

Rhizosphere

The area around a plant root that is inhabited by a unique population of microorganisms influenced by the chemicals released from plant roots.

Rhizosphere

The rhizosphere, the narrow region of a soil that is directly influenced by root secretions and associated soil microorganisms, is the thin cylinder immediately surrounding the root, serving as the interface between the root and the rooting medium.

Rhizosphere

Parts of rhizosphere

Endorhizosphere, Rhizoplane, Ectorhizosphere

includes portions of the cortex and endodermis in which microbes and cations can occupy the "free space" between cells (apoplastic space).

endorhizosphere

medial zone directly adjacent to the root including the root epidermis and mucilage.

rhizoplane

•Outermost zone •Extends from the rhizoplane out into the bulk soil.

ectorhizosphere

studied the importance of mineral elements were done and plant nutrition was established as a scientific discipline

Justus von Liebig (1803-1873)

Based on Carl Sprengel (1840) but popularized by Justus von Liebig , It states that growth is dictated not by total resources available,but by the scarcest resource (limiting factor).

Liebig’s Law of Minimum or Liebig’s Law

The term essential elements (or mineral nutrient) was proposed by

Arnon and Stout in 1939

The term essential elements (or mineral nutrient) was proposed by Arnon and Stout in 1939 for any element that satisfies the following criteria:

It is needed for the completion of the plant’s life cycle, It causes a specific deficiency when it is unavailable , It must be directly involved in the plant metabolism

There are ____ established Essential Elements, however, this varies in some literature.

Nutrients that are needed and found in plants in larger quantities

Macronutrients

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulfur

Macronutrients Maybe classified into three groups:

Structural Elements/Nutrients (C,H,O) , Primary Elements/Nutrients (N,P, K) , Secondary Elements/Nutrients (Ca, Mg, S)

Micronutrients also known as ?

trace elements

also known as trace elements, are needed and found in plants in relatively smaller or minute quantities.

Micronutrients

Chlorine, Iron, Boron, Manganese, Zinc, Copper, , Molybdenum, Nickel

Functions of Essential Elements Essential elements have specific vital functions in plant metabolism. Each can perform one or more of the following general functions:

• Constituent of organic structures (C, H, O, N, S, and Mg) , •Activator of enzyme reactions or charge carrier (Fe, Cu, Zn, Mo, Mn, and Ni) , •Involvement in osmoregulation or maintenance of electrochemical equilibrium (K, Cl, and Ca) , • Involvement in energy transfer reactions (P and B)

Functions of essential elements

Yield, Fruit size, Fruit number, Fruit weight , Firmness , TSS or total soluble solids, Bitter pit, Internal breakdown , Fruit rota, Acidity/ Vitamin C, Coloration, Alfalfa Greening

Factors affecting the availability of Micronutrients

Ph >7.0, Ph <5.5, Water- logged soil, draught , High humus content, High P- content, Sand, Compaction

or sugar content that measures and includes the carbohydrates, organic acids, proteins, fats and minerals of the fruit. From 10-20% of the fruit’s fresh weight and increases as fruit matures producing less acidic, sweeter fruit.

total soluble solids

a disorder which causes dark-green, slightly sunken spots on the skin of fruits (e.g. pears).

Alfalfa Greening

There are two sources of nutrients in the soil

Native, Added components

derived from the decomposition of plant residues and soil organic matter

Native

sourced from the addition of fertilizers and manure

Added components

those that are chemically bound to soil particles, are not immediately useful.

Undissolved or granular nutrients

Factors that improve a plant's ability to use nutrients

• Type of soil , • Soil pH , • Types of nutrients in the soil , • Amount of soil water , • Anything that affects the plant's growth

Negatively charged ions

Anion

Positively charged ions

Cation

Type of soil

Sandy, Clayey, Loamy

is the single most important chemical property of the soil

Soil pH

The most favorable soil pH for most agricultural crops is between

6.0 and 7.0 (Optimum = about 6.5)

can have high concentrations of soluble Al, Fe, and Mn which may be toxic to the growth of some plants.

Strongly acid soils (4.0 – 5.0)

Crops in increasing acidity

Maize, Wheat, Cowpea , Bermuda grass, Potatos, Sugarcane , Tobacco

Crops in Increasing Alkalinity

Rice, Beans, Groundnut , Soybean , Cotton , Rape, Sunflower

For a plant to utilize the these nutrients, it must first be?

absorbed

Plants normally absorb nutrients in the soil. However, plants can also absorb nutrients through the leaves. E.g. ?

foliar fertilizers

Mechanisms by which plants absorb nutrients from the soil

Soil Solution Mechanism, Contact mechanism

Exchange takes place at the root hair surface, ions being absorbed from solution in exchange for ions excreted by the roots

Soil Solution Mechanism

the soil solution is bypassed ad exchange takes place directly between the soil particle and the root. Both root surface and clay particle have exchangeable ions and when the root contacts the clay particle, the ion exchange takes place.

Contact mechanism

nutrients move from areas of high to low concentration, without the expenditure of energy by the plant.

Passive transport

nutrient ions move against a concentration gradient involving the expenditure of energy.

Active Transport

Lack of soil ______ hinders production of energy by the roots and therefore limits nutrient uptake.

oxygen

Very mobile

Mg, N, P, Cl, K

Slightly mobile

S, Ni, Co

Immobile

Fe, Cu, Zn, Mn, Mo

Very Immobile

B, Ca

The driving force that moves water, ions, and other dissolved solutes in this complex vascular system comes from a number of sources:

Transpiration , Root pressure , Source- Sink phenomenon

of water from the leaf surfaces of the plant, which water from the rooting medium into the root and then up the entire plant

Transpiration

exerted from the roots themselves, pushing water and ions up the plant

Root pressure

draws water, ions, and solutes from inactive to active expanding portions (growing points, developing fruit, grain, etc.) of the plant.

Source-sink phenomenon

are being used in breeding programs to select on the basis of tolerance to certain soil conditions (such as soil salinity) and to remove from the gene pool undesirable traits, to make the plant unsuitable for use as feed for animals or food for human consumption.

Genotype differences

Plants need ____, ____, _____, _____,for growth

CO2, water, light, nutrients

The yield response curves for a particular nutrient are asymptotic; when a supply of one nutrient (or other growth factor) is increased, other nutrients (or growth factors) become limiting factors.

Law of Diminishing Yield Increment

Abundance of plant nutrient may cause ?

inversion

The inversion may be caused by:

• Toxicity of a nutrient , • Induced deficiency of other nutrients

In most crops, both ______ (e.g., dry matter yield in tons per hectare) and ______ (e.g., content of sugars or protein) are important yield components.

quantity, quality

Plants are ______?, which means they can produce their own food.

autotrophs

auto meaning Trophos meaning

self, feeder

Plants harness light as a source of energy to produce food through the process called ?

photosynthesis

It is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.

Photosynthesis

Greek: Photo meaning ____ and synthesis meaning to _____

light, combine

Raw materials for photosynthesis

H2O, CO2, Minerals

100

Formula of photosynthesis

6CO2 + 6H2O = C6H12O6 + 6O2

Soil Tech Midterm 1

Mutated Lemon · 100問 · 2年前

Soil Tech Midterm 1