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Crop physiology and plant nutrition (Subject) / Crop Physiology and Plant nutrition (Lesson)
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- Why is it recommended to carry out soil/plant nutrient analysis? -make fertilizer recommendations -possible toxicity/deficiency -calibrate fertilizer application to plant response
- What are plant macronutrients? (10) -O -C -H -N -P -K -Ca -Mg -S (-Si)
- What are plant micronutrients? (10) -Cu -Fe -Mn -Ni -Zn (-Co) (-Na) -Bo -Cl -Mo
- Name five pools of soil nutrients -soil solution -adsorbed to colloids -organic matter -amorphous minerals -within primary and secondary minerals
- What part of soil nutrients is important in nutrient analysis and how is it tested for? -Plant available nutrients -testing by using extraction agents mimicking root activity
- What do roots/plants do to obtain nutrients from the soil? (5) -interception of ions -transpire water (mass flow) -create concentration gradients (diffusion) -acidification of the rhizosphere -symbiosis with mycorrhiza or N-fixing bacteria
- What is the standard procedure of plant nutrient analysis? -Drying plant matter at 80°C -grinding -destroying the organic matter by thermal oxidation or acid digestion
- What are the options for analyzing the nutrient concentration in soil/plant extracts? -spectrophotometry -separation of ions (ion-specific electrode, ion chromatography)
- What are the drawbacks of soil and plant nutrient analysis? soil: only indicates the potential availability of nutrients plant: gives only a snapshot of nutritional status
- How to define stress to plants? Stress is a condition preventing plants from fully expressing their genetic potential for growth, development and reproduction.
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- What induces biotic stress in plants? -competition -predation -parasitism -allelopathic chemicals
- What are the two categories for symptoms of plant stress? -invisible symptoms (enzyme activity, change in biomembranes) -visible symptoms (necrosis, chlorosis, predation damage)
- define abiotic stress Disease or injury can occur when any of several environmental factors are outside a plant's normal range or requirement. The abiotic factors most commonly involved are temperature, light, moisture, wind, mineral nutrients and pH
- What makes the diagnosis of abiotic plant diseases hard? -many abiotic factors cause similar symptoms -symptoms may resemble those of biotic disease -the abiotic factor causing the disease may not be present at the time of detection -invasion of damaged plant tissue by biotic agents
- What happens during flooding? -much slower gas diffusion -changes in soil conditions (anaerobic, accumulation of toxins) -changes in light conditions (depends on sediment load) -physical damage caused by flooding and/or subsequent erosion
- How do soil microbes react to anaerobic conditions? Use of alternate electron acceptors ->formation of toxins
- How have plants adapted to deal with flooding? -aerenchyma (programmed cell death caused by ethylene) -adventitious roots -shoot elongation (regulated by ethylene and gibberellin) -in rice formation of barrier to radial oxygen loss
- Which proteins allow plants to detect light? -cryptochrome -phototropin
- Which types of photoperiodism are found in plants? -long-day plants -> flower when day time exceeds critical day length -short-day plants -> flower when day time is shorter than critical day length -day-neutral plants -> are photoperiodically insensitive
- How do stable isotopes differ from common isotopes? Different number of neutrons
- How do stable isotopes differ from common isotopes? Different number of neutrons
- How do stable isotopes differ from common isotopes? Different number of neutrons
- How can plant nutrients be classified based on their physiological and functional behavior? -assimilated nutrients: C, O, H, N, S -ester-forming nutrients: P, B, Si -free and sorbed nutrients: K, Na, Cl, Ca, Mg -chelated nutrients: Fe, Ni, Cu, Zn, Mn, Mo
- name the four zones of a root -root hair zone -elongation zone (elongation, root exudation) -meristematic zone (cell growth, root exudation) -root cap (mucilage)
- Which are the three ways nutrients are transported through the root cortex (short distance transport? -symplastic transport (nutrients are transported through the cells by joined cytosol (plasmodesmata)) -apoplastic transport (nutrients are transported between cells) -transmembrane transport (through cells via cell membranes)
- Name ten adaptation mechanisms plants use to deal with nutrient deficiency? -larger root system and exploitation of larger soil volume -higher root-shoot ratio -higher root length density -local increase of roots (cluster roots) -using different rooting patterns in time and space in plant communities -exudation of protons, organic acids, phenolic compounds and enzymes -changing rhizosphere pH -altering the redox situation -solubilizing nutrients from solids -activating soil microorganisms
- name three ways nutrients are transported to the root surface -mass flow (driven by transpiration) -diffusion (driven by concentration gradient) -interception (root growth)
- How can nutrients be transported through cell walls? -uniport by carriers/channels (passive) -symport/antiport by carriers (secondary active) -pumps (primary active)
- Which types of substances are mainly transported by the xylem? -water -mineral nutrients -metabolites -signaling molecules (proteins)
- How is xylem transport driven? -transpiration via the leaves -capillary forces in the xylem (adhesion/cohesion) -absorption via the roots -> day -increased osmotic potential in the xylem -> night
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- Which types of transport are present in xylem loading? (5) -active transport of H+ -Active antiport of H+ and cations -channels for passive anion transport -active transport of Ca2+ -K channels (passive uniport)
- Which types of transport are present in phloem loading? (4) -Active transport of H+ -Active transport of Ca2+ -K channels (passive uniport) -Symport of H+ and anions/sugars/amino acids
- What is the driver of phloem transport? -active transport of solutes into the phloem ->higher solute concentration ->influx of water ->movement by mass flow
- Which nutrients are phloem mobile/partly mobile/immobile? Mobile: N, P, K, Mg, Cl Partly mobile: S, Fe, Zn, Mo, Cu Immobile: Ca, Mn, B
- What are plant hormones? natural substances that control plant activities can be synthesized to initiate reactions in plants
- What are the functions of auxin? (5) -cell elongation -tropisms (phototropism, gravitropism) -apical dominance (dominance of the main stem over side branches) -formation of adventitious roots -prevention of leaf abscission
- Where are cytokinins produced? roots and young fruits
- What are the functions of cytokinins? -cell division -formation of new roots and shoots -stimulation of germination -influence on the transport of nutrients and metabolites -delay of senescence
- When is root/shoot growth stimulated by auxin and cytokinin? high auxin, low cytokinin ->roots low auxin, high cytokinin ->shoots
- Where are abscisic acids produced in plants? plastides -> chloroplasts, amyloplasts transport via xylem & phloem
- What are the functions of abscisic acids? -stimulates closing of the stomata -inhibition of growth -seed dormancy
- Where are gibberellins synthesized in plants? -immature seeds -root and shoot apical meristem -developing anthers and pollen
- What are the functions of gibberellins? -cell division and elongation (increased growth) -breaking dormancy of seeds and dormant buds -induces germination -prevents flowering -development of seedless fruits
- Where is ethylene synthesized in plants? -ripening fruits -senescent leaves and flowers
- What are the functions of ethylene? -inhibition of growth -abscision (in combination with low auxin) -promotion of senescence -fruit ripening -gummosis -thigmomorphogenesis (stunting due to mechanical disturbance) -forming a hook during seed germination -production of aerenchyma under waterlogged conditions
- Which processes dictate the availability and mobility of micronutrients and toxins -ion exchange -chemisorption -precipitation and dissolution -complexcation -immobilization by plant or microbial uptake -weathering -leaching
- What stimulates the uptake of metals from the rhizosphere? -acidification of the rhizosphere -chelation of metals
- How does the uptake of iron differ in dicots and monocots? Dicots have a protein in the cell membrane that reduces the Fe3+ to Fe2+ and transports it into the cell while releasing the chelate back to the soil solution. In Monocots the whole complex is transported into the cell where the iron is reduced to Fe2+ and the chelate is then exuded from the cell back into the soil solution.
- What has to be taken into account when fertilizing with micronutrients? The luxury range for micronutrients is rather narrow so toxicity has to be avioded
- Name the functions of Zn in plants (2) -enzyme constituent important for biomembrane structure -promotes growth hormones and seed production