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Crop physiology and plant nutrition (Subject) / Crop Physiology and Plant nutrition (Lesson)
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- Name the functions of Fe in plants -enzyme constituent -important for chlorophyll biosynthesis
- Name the functions of Cu in plants -Enzyme constituent -important in protein/carbohydrate metabolism
- Name the functions of Mn in plants -Enzyme activator -important in N metabolism/assimilation
- Name the functions of Ni in plants (2) -needed for Fe absorption -constituent of urease enzyme
- Name the functions of B in plants -Enzyme activation -essential for cell division and development
- Name the functions of Mo in plants -important in N fixation and assimilation -important for growth hormone synthesis
- Name the functions of Cl -important for photosynthesis -enzyme activation
- What is the biggest anthropogenic source of metals in soils? Fly ash
- What kind of physiological damage do toxic elements cause to plants? -oxidative damage (creation of reactive oxygen species) -biomolecule dysfunction -enzyme inactivation (displacement of activator)
- What are the symptoms of toxicity of heavy metals? -brown, stubby root system -other induced deficiencies -inhibited growth
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- What are the mechanisms of plants to deal with toxic elements? (7) -selective uptake of ions -chelating of ions outside plant cells -binding ions to cell walls -efflux of element excess from roots -immobilization as compounds, also minerals -volatilization of toxic elements -removal of elements with falling leaves/needles
- Name a problem caused by B toxicity Interference with Mn-dependant enzymatic reactions
- Which nutrient uptake is suppressed by Al toxicity? Ca, Mg, K
- What are the three factors affecting micronutrient and toxin solubility? -OM -pH -redox potential
- Name four types of N uptake by plants -as NO3-/NH3/amino acids through channels (passive) -co-transport of H+ and NO3-/NH3/amino acids -antiport of H+ and NH4+ or OH- and NO3- -through symbiosis with mycorrhiza
- Which two factors are influenced by increased N availability in grains? -baking quality/protein content increased -nutritional value (lysine content) decreased
- Which two factors are influenced by N increased availability in sugar beets? -beet yield increased -sugar content decreased
- Why is the demand for sulfur fertilization rising over the last decades? (3) -cleaning up of SO2 emissions -elimination of S content in NPK fertilizer -removal of S by high yielding varieties
- How are specific forms of S taken up by plants? -SO4²- via roots -SO2 via stomata -org S as amino acids
- How is S transported within the plant and where do deficiency symptoms show first? S is phloem mobile Deficiency symptoms usually show on older leaves but at high N availability they can show on younger leaves as S is immobilized as proteins
- How is SO4²- taken up by plant roots? (3) -Symport of H+/Na+ and SO4²- -antiport of SO4²- and anions -SO4²- pumps
- Which forms of S are present in plants? (3) -SO4²- -S²- -organic sulfur ->amino acids ->proteins ->coenzymes ->secondary plant metabolites
- Name three types of inorganic sulfur fertilizer and their S content -Sulfuric ammonia (24% S) -Kieserite (MgSO4²-) (20-22% S) -Epsom salt (MgSO4²-) (13% S)
- How long are phosphorous reserves predicted to last? 350 years
- How is P taken up by plant roots? -antiport of OH- and H2PO4- -(at alkaline/neutral soil conditions) antiport of OH- and HPO4²- -symbiosis with mycorrhiza
- Which forms of P are found in plants? (5) -inorganic P (H2PO4-/HPO4²-) -ATP -Phospholipids -Nucleic acids -phytine
- What are the symptoms of P deficiency in plants? (4) -dark green colour (chlorophyll increase due to smaller cells) -blue/red discoloration -erect leaves -reduced root growth
- How can P deficiency be induced by abiotic factors? drought ->low soil water content ->low P availability
- How is P precipitated in soils? -under acidic conditions as Fe-/Al-phosphate -under alkaline/neutral conditions as Ca-phosphate
- Which minerals are the basis for P fertilizer? -rock phosphate (apatite/Ca-P, phosphorites)
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- name two types of P fertilizer that could be used foliar application -superphosphate -triplesuperphosphate
- What is the common unit for P fertilizer and what is the actual P content? P2O5 x 0.436 = P
- Which other nutrient increases the effectiveness of P fertilization N and P combined
- How is P transported in the plant and where do deficiency symptoms show first? P is phloem mobile Symptoms show on older leaves first
- Is B phloem mobile/immobile and where do deficiency symptoms show first? B is phloem immobile Symptoms show on younger leaves first
- Which forms of B are found in plants? (5) -inorganic B (H2BO3-/HBO3²-) -organic B ->stabilization of cell walls (can't be remobilized) ->boric ester acid (carbohydrate metabolism) ->nucleotide synthesis ->pollen germination
- name three symptoms of B deficiency -chlorosis and necrosis on young leaves -reduced growth of young tissue -hollow stems and roots
- Which types of soils are usually high in B? marine soils
- Name three types of B fertilizer (one highly soluble, soluble and slightly soluble) and their B content -Solubor (highly soluble, 21% B) -sodiumtetraborate (soluble, 11% B) -Colemanite (slightly soluble, 16% B)
- What are the effects of adequate Si nutrition in plants? (5) -improves resistance against plant pathogens -P mobilization -detoxifies Al -increases chlorophyll content -increases sugar content
- For which types of plants is Si a beneficial element? Gramineae (rice, sugar cane)
- Which types of Si are found in plants? (4) inorganic Si: -H2SiO4/H3SiO4- -amorphous SiO2 minerals organic Si: -as Si-cellulose in epidermal cell walls of monocots -in dicots probably stored in the cell
- Name one highly soluble, one soluble and one poorly soluble for of Si fertilizer -highly soluble: potassium silicate -soluble: calcium silicate -weakly soluble: Quartz
- Name one highly soluble, one soluble and one poorly soluble for of Si fertilizer -highly soluble: potassium silicate -soluble: calcium silicate -weakly soluble: Quartz
- From which types of minerals does Ca mainly originate? (5) primary minerals: -feldspath -apatite secondary minerals: -lime -gypsum -Ca-phosphates
- Which types of soil conditions provide a problem to the supply of Ca? (3) -soils with high OM content -acidic soils -alkaline soils (low availability)
- Which nutrient works as an antagonist to Ca uptake Ca2+/K+ antagonism
- Which types of minerals work as a source for Mg? (7) -augit -olivine -biotite -vermiculite -montmorillinite -magnesite -dolomite
- Under which soil conditions is Mg usually deficient? (2) -high OM soils -acidic soils with low CEC (leaching)
- Which types of ions work antagonistic/synergistic to Mg availability? -other cations (H+, NH4+, Ca2+, K+, Mn2+) work as antagonists -NO3- works synergistically