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30 Cards in this Set
- Front
- Back
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Criteria for determining essentiality
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1. necessary for normal development and reproduction through a full life cycle.
2. restoration of growth/reproduction occurs only with that element (no substitute will suffice) 3. must be taken up by the plant and used internally. |
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Methods for determining essentiality
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1. study chemical composition
2. hydroponics |
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First 6 mineral nutrients found by Knops & vonSachs
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Ca+2, K+, Mg+2, NO3-, PO4-2, SO4-2
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Macroelements
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Ca+2, K+, Mg+2, H2PO4-, NO3-, SO4-2
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Relative uptake of macroelements in wheat
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N>K>P>Ca>Mg/S
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Microelements
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Fe+2, Mn+2, Zn+2, Cu+2, MoO4-2 (molybdenum), Cl-, Boron( BO3-2)
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Nitrogen
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NO3-, macroelement. amino acids (proteins), nucleic acids (DNA/RNA), chlorophyll
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Phosphorus
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H2PO4-, macroelement. ATP. nucleic acids (DNA/RNA) and other sugar phosphate. phospholipid.
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Sulfur
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SO4-2, macroelement. amino acid (methionine & cysteine), Coenzyme A, Fe-S cluster involved in photosynthesis
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Potassium
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K+, macroelement. main cation in cells (osomotic levels in cytoplasm - turgor). enzyme activation
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Calcium
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Ca+2, macroelement. secondary messenger, enzyme regulation, cell wall (middle lamella) afftects membranes.
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Magnesium
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Mg+2, macroelement. chlorophyll, enzyme activation, nucleic acid metabolism, RNA/ribosome structure.
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Iron
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microelement (Fe+2), chlorophyll synthesis, cytochrome, Fe-S cluster
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Copper
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microelement (Cu+2), plastocyanin (electron transfer in photosynthesis)
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Manganese
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microelement (Mn+2), chlorophyll synthesis, necessary for enzyme (oxidase)
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Zinc
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microelement (Zn+2) - activates enzymes, transcription
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Molybdenum
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nitrate reductace (reducing and metabolizing nitrogen)
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Manganese
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chlorophyll synthesis, necessary for oxidase enzyme
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Zinc
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activate enzyme, transcription
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Molybdenum
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nitrate reductase (reducing and metabolizing nitrogen)
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Chlorine
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unknown - photosynthesis, release of oxygen
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Boron
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unknown
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Sodium
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needed by mangroves and salt marsh plants
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Silicon
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some grasses are silica -rich, stinging needed
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Selenium
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some species in Se-rich soils accumulate Se and become very toxic
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5 Soil Components
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1. inorganic particles
2. water 3. organic particles 4. air 5. organisms |
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Soil Particle Size Categories
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1. coarse sand (0.2 - 2.0 mm)
2. fine sand (0.02 - 0.2 mm) 3. silt (0.002- 0.02 mm) 4. clay (<0.002 - 2 um) |
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Significance of soil composition
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Determines amount of water (and dissolved minerals) soil can hold
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What happens after rain?
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H20 drains into aquifer
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field capacity
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amount of H20 remaining
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