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Chapter 14 - Soils and Mineral Nutrition - Coggle Diagram
Chapter 14 - Soils and Mineral Nutrition
Soils and Mineral Availability
Cation Exchange - Roots/Root Hairs respire, give off carbon dioxide -> dissolves in soil solution, reacting chemically with water, forms carbonic acid - > breaks down into a proton and a bicarbonate ion -> further disassociates into a second proton and carbonate ion -> acidifies the soil adjacent to roots and root hairs -> protons diffuse, bounce close to a bound cation at micelle surface, disrupting the electrical attraction of cation and trapping it.
Soil Acidity - Acidity Increases - greater concentration of protons causes more cations to be released from micelles. Extremely Acidic Soil - loses cations rapidly, soil becomes poor. High Alkaline Soil - too few protons to allow cation release, concentrations of minerals become excessive.
Weathering - Physical (breakdown of rock by physical forces, wind, water, temperature - coarse sand -> fine sand -> silt -> clay particles/micelles) and Chemical (chemical reactions, acids, decaying bodies - alters soil chemistry)
The Endodermis and Selective Absorption of Substances - Endodermis prevents uncontrolled apoplastic diffusion in roots, highly selective permeability.
Mycorrhizae and the Absorption of Phosphorous - Plants forming a symbiotic relationship with soil fungi, symbiosis permits plants to absorb phosphorous.
Essential Elements
Criteria For Essentiality - 1) Element must be necessary for complete, normal plant development through a full life cycle. 2) Element itself must be necessary and no substitute can be effective. 3) Element must be acting within the plant, not outside it.
Minor/Micro Essential Elements (Trace Elements) - Iron/Boron/Chlorine/Copper/Manganese/Molybdenum/Zinc
Major/Macro Essential Elements - Calcium/Nitrogen/Potassium/Phosphorus/Magnesium/Sulfur
Mineral Deficiency Diseases
Symptoms of Deficiency Diseases - Chlorosis (Leaves lack chlorophyll, brittle and papery, yellowish), Necrosis (Death of patches of tissue).
Mobile Elements - Chlorine/Magnesium/Nitrogen/Phosphorous/Potassium/Sulfur - Even after being incorporated into plant tissue, they can move. Can move to younger tissue.
Causes of Deficiency Diseases - Excessive Concentrations, Osmotic Drought, Acid Soils (Aluminum Toxicity), Mine Tailings, Competition, Harvesting Crops
Immobile Elements - Boron/Calcium/Iron - After incorporated into plant tissue, remain in place, cannot be moved to younger parts of plant.
Nitrogen Metabolism
Nitrogen Fixation - conversion of N2 gas into nitrate, nitrite, or ammonium. Nitrogenase - enzyme that uses N2 as substrate.
Other Aspects of Prokaryotes and Nitrogen - Nitrifying Bacteria, oxidize ammonium to nitrite or nitrite to nitrate, all called nitrification.
Nitrogen Assimilation - Actual incorporation of ammonium into organic molecules in the plant body.
Obtaining Nitrogen from Animals - Carnivorous Plants, capturing/eating animals. Ant-plants, ants use areas of the plant as homes, and as they die the plant absorbs nitrogenous compounds via the walls or the roots. (Mutualistic)
Nitrogen Reduction - Process of reducing nitrogen in the nitrate ion from an oxidation state of +5 to the -3 oxidation state of ammonium.
Storage of Minerals Within Plants
All parts of a plant except seeds store minerals in soluble form. During formation of flower buds and fruits/seeds, need for essential elements increases. Seeds store minerals, not the same way as the other parts of the plant do.