give some summary on mineral nutrition chapter in bio class 11
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INTRODUCTION
Soil the main source of mineral nutrients. These mineral nutrients are mainely absorbed by the meristemetic region of roots.
Mineral nutrients are present with soil particles in colloidal form and in water as soil solution. Conduction of mineral nutrients is done through the xylem.
Absorption of meneral in plant is an active process.
ESSENTIAL ELEMENTS
About 50-60 elements are present in plant body but 16 elements are considered as essential elements
According to Arnon-Criteria of essentiality of minerals:
The element must be neccessary for normal growth and reproduction of all plants.
The requirement of element must be specific for plant life. That is indespensible element to plant.
The Element must be directly involved in metabolism of plant.
C, H, O, N, K, S, Ca, Fe, Mg, P, Cu, Mn, B, Cl, Zn, Mo, Ni
CLASSIFICATION OF ESSENTIAL ELEMENTS
Arnon divides these necessary elements in two group on the basis of requirement of plant Major element/Macro nutrients: Concentration must be 1-10 mg L–1 more than 10 m mole
kg–1of dry matter. (mmole-Milimolar)
C, H, O, N, P, Mg, S, K, Ca
Minor element/Micro nutrients: (Concentration present 1.0-0.1 mg L–1 less than 10 m mole kg–1 per gram of dry matter)
Cu, Zn, N, Mo, Mn, B, Cl, Fe
General functions of essential elements-
1. Protoplasmic elements - C, H, O, N, P, S
2. Elements of Redox Reaction - Fe, Cu, Mn, Cl
3. Balancing / Antagonetic - K, Ca
4. Membrane Permeability - K, Ca
5. Co-factor of enzymes - All micronutrients except B
6. Osmotic pressure of cell.
Benificial nutrients: Mineral elements other than essential elements, which satisfy specific additional nutrient requirement of some specific plants.
Ex. Na - Halophytes (eg. Atriplex - helps in C4 pathway)
Si - Grasses (Provides mechanical strength)
Se - Astragalus
Co - Leguminous plants (root nodule formation)
Toxic elements/Toxicity:- Any mineral ion concentration in plant tissue, that reduces the dry weight of tissue by about 10 percent is considerd as toxic or toxic element and this effect is called toxicity.
Most of the micronutrients become toxic as their required amount for plants is very low. This excess concentration inhibits activity of other essential elements.
Ex : Toxicity of Mn (Manganese) may induce deficiency of iron, magnesium and calcium cause appearance of brown spots surrounded by chlorotic veins. Mn competes with iron (Fe) and magnesium (Mg) for uptake and for binding to enzymes. Mn also inhibits, calcium translocation into the shoot apex and causes disease 'Crickle leaf '.
So the dominant symptoms of Mn toxicity may actually be the symptoms of Fe, Mg and Ca deficiency.
Deficiency symptoms and mobility of minerals.
The deficiency symptoms of highly mobile elements in plants like N, P, K, Cl and Mg first appear in older plant parts. These minerals are present as structural constituent of biomolecules of mature plant parts and when plant parts become older, these biomolecules broken down making these elements available for younger plant parts.
The deficiency symptoms of immobile elements like Ca, S, B, Fe first appear in young plant parts,as they are not transported from older plant parts.
MINERAL SALT ABSORPTION/M ECHANISM OF MINERAL ABSORPTION
(A) Passive absorption of minerals : (Without expenditure of ATP)
(1) By simple diffusion : According to this method mineral ions may diffuse in root cells from the soil solution. Facilitated diffusion of minerals also occurs with help of carrier proteins.
(2) By mass flow : Proposed by Hymo (Supported by Kramer) According to this method mineral ions absorption occurs with flow of water under the influence of transpiration.
(3) By ion exchange : By Jenny and Over street. This is exchange of mineral ions with the ions of same charge.
(i) By contact exchange : When the mineral ion exchange occurs with the H+ and OH– ions.
(ii) Carbonic acid exchange : When the mineral ion exchange takes place with the ions of carbonic acid.
Soil the main source of mineral nutrients. These mineral nutrients are mainely absorbed by the meristemetic region of roots.
Mineral nutrients are present with soil particles in colloidal form and in water as soil solution. Conduction of mineral nutrients is done through the xylem.
Absorption of meneral in plant is an active process.
ESSENTIAL ELEMENTS
About 50-60 elements are present in plant body but 16 elements are considered as essential elements
According to Arnon-Criteria of essentiality of minerals:
The element must be neccessary for normal growth and reproduction of all plants.
The requirement of element must be specific for plant life. That is indespensible element to plant.
The Element must be directly involved in metabolism of plant.
C, H, O, N, K, S, Ca, Fe, Mg, P, Cu, Mn, B, Cl, Zn, Mo, Ni
CLASSIFICATION OF ESSENTIAL ELEMENTS
Arnon divides these necessary elements in two group on the basis of requirement of plant Major element/Macro nutrients: Concentration must be 1-10 mg L–1 more than 10 m mole
kg–1of dry matter. (mmole-Milimolar)
C, H, O, N, P, Mg, S, K, Ca
Minor element/Micro nutrients: (Concentration present 1.0-0.1 mg L–1 less than 10 m mole kg–1 per gram of dry matter)
Cu, Zn, N, Mo, Mn, B, Cl, Fe
General functions of essential elements-
1. Protoplasmic elements - C, H, O, N, P, S
2. Elements of Redox Reaction - Fe, Cu, Mn, Cl
3. Balancing / Antagonetic - K, Ca
4. Membrane Permeability - K, Ca
5. Co-factor of enzymes - All micronutrients except B
6. Osmotic pressure of cell.
Benificial nutrients: Mineral elements other than essential elements, which satisfy specific additional nutrient requirement of some specific plants.
Ex. Na - Halophytes (eg. Atriplex - helps in C4 pathway)
Si - Grasses (Provides mechanical strength)
Se - Astragalus
Co - Leguminous plants (root nodule formation)
Toxic elements/Toxicity:- Any mineral ion concentration in plant tissue, that reduces the dry weight of tissue by about 10 percent is considerd as toxic or toxic element and this effect is called toxicity.
Most of the micronutrients become toxic as their required amount for plants is very low. This excess concentration inhibits activity of other essential elements.
Ex : Toxicity of Mn (Manganese) may induce deficiency of iron, magnesium and calcium cause appearance of brown spots surrounded by chlorotic veins. Mn competes with iron (Fe) and magnesium (Mg) for uptake and for binding to enzymes. Mn also inhibits, calcium translocation into the shoot apex and causes disease 'Crickle leaf '.
So the dominant symptoms of Mn toxicity may actually be the symptoms of Fe, Mg and Ca deficiency.
Deficiency symptoms and mobility of minerals.
The deficiency symptoms of highly mobile elements in plants like N, P, K, Cl and Mg first appear in older plant parts. These minerals are present as structural constituent of biomolecules of mature plant parts and when plant parts become older, these biomolecules broken down making these elements available for younger plant parts.
The deficiency symptoms of immobile elements like Ca, S, B, Fe first appear in young plant parts,as they are not transported from older plant parts.
MINERAL SALT ABSORPTION/M ECHANISM OF MINERAL ABSORPTION
(A) Passive absorption of minerals : (Without expenditure of ATP)
(1) By simple diffusion : According to this method mineral ions may diffuse in root cells from the soil solution. Facilitated diffusion of minerals also occurs with help of carrier proteins.
(2) By mass flow : Proposed by Hymo (Supported by Kramer) According to this method mineral ions absorption occurs with flow of water under the influence of transpiration.
(3) By ion exchange : By Jenny and Over street. This is exchange of mineral ions with the ions of same charge.
(i) By contact exchange : When the mineral ion exchange occurs with the H+ and OH– ions.
(ii) Carbonic acid exchange : When the mineral ion exchange takes place with the ions of carbonic acid.
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Explanation:
Mineral nutrition is the study of source, mode of absorption, distribution and metabolism of various inorganic substances (minerals) by plants for their growth, development, structure, physiology and reproduction. Hydroponics is the technique of growing plants in nutrient solution in complete absence of soil.
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