AGRY 525 Quiz III

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MRK
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264559
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AGRY 525 Quiz III
Updated:
2014-03-05 15:54:13
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Translocation mineral nutrients
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Quiz III Cards
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  1. Translocation
    • Moving carbon from different areas
    • Sink
    • Source- supply sinks near them
    • Proximity Matters
    • Fick's law applies
  2. Sink
    • tissue that is a net importer of organic nutrients
    • Seed
    • root tip
    • meristem
  3. Source
    • tissue that supplies sinks with needed organic nutrients
    • leaves
    • storage organs (rhizomes, stolon, stem base, taproots)
  4. Who discovered mass flow?
    Münch
  5. Diffusion
    • High [sucrose] in sources
    • low [sucrose] in sinks
    • Thus C flows from source to sink
  6. Facilitated Diffusion
    • Active loading of sucrose in source tissues
    • increase [sucrose] in source
    • Takes ATP b/c [sucrose] in sieve element is higher than companion cell
    • Sink tissues (such a thing as active unloading ? na)
  7. Sink tissues
    • convert sucrose to something else
    • cellulose, starch fructan
    • only diffuse against own gradient
    • kepp [sucrose] low so ∆c^^^
  8. Psiw
    • water potential
    • = 0 when no forces acting on it (ie pure water)
  9. Psis
    • solute potential
    • (-)
    • less water b/c something is in it
    • more solutes = more negative
  10. Psip
    • pressure potential
    • (+)
    • turgor pressure
    • moves solutes in phloem
  11. water potential equation
    Psiw = Psis + Psip
  12. % of dry matter from soil
    5
  13. Essential Nutrients
    • Needed for Normal Growth and reproduction
    • clear function in plant physiology
  14. Root Nutrient Contact
    • Root interception
    • Diffusion
    • Mass flow
  15. Root Interception
    • Growth causes roots to contact nutrients
    • Minor role in nutrient uptake
    • gives maybe 1% of K needed for Rye
  16. Diffusion
    • Transport from high -> low concentration in the soil
    • Driven by fick's law (∆c/∆d)
    • Depletion at root surface = ^ ∆c
    • Important for K and P b/c taken up in large amounts
  17. Mass Flow
    • Nutrients suspended in H2O => transpiration stream
    • Transpiration rate; average concentration of elements in H2O
    • NO3- SO4- Ca2+ Mg2+ Micronutrients
  18. Anatomy of phloem sieve tube - companion cell complex
    • sieve tube
    • connected by plasmodesmata
    • Companion cells
    • together make up phoelm
  19. Sieve tube
    • sieve plate
    • alive
    • some have pores
    • contain p-protien in callose which seals ends if broken
  20. Companion Cells
    • or Transfer cells
    • lots of undulation in cell wall (more area for transport)
    • Lots of mitochondria
  21. Symplastic flow
    • stays inside the cells
    • through plasmdesmata
  22. Apoplastic flow
    • uses ATP to pump H+ outside
    • creates pH 5.5
    • Sucrose-H+ symporter brings H+ back with sucrose
    • creates high [sucrose] and low H+ inside ) pH 7
  23. active loading
    increases the ∆c and increases the rate
  24. Differences is rate of C translocation in phloem
    • C3 50 cm/hour
    • C4 200 cm/hour
  25. Distrubution of C photosynthate in legumes
    • same side of stem
    • vascular orthostichy near direct vascular connections that override proximity effects
  26. alteration of source sink in sugar beet
    • patterns altered if source sink changes imposed
    • ie leaves taken off
  27. composition of phloem from caster bean
    • 80% sucrose
    • 2% protien
  28. List essential Nutrients
    C HOPKNS CaFe Mg B Mn CuZn MoNiCl
  29. Role of N
    main mode of uptake
    • protiens
    • mostly taken up by mass flow
  30. Role of P
    main mode of uptake
    • ATP
    • diffusion
  31. Role of K
    Main mode of uptake
    • Role in stomatal movements
    • Diffusion
  32. Role of S
    component in protiens
  33. Role of Ca
    Main mode of uptake
    • constituent of the middle lamella of cell walls
    • Mass flow
  34. Role of Mg
    constituent of the chloropyll molecule
  35. Role of Fe
    constituent of cytochromes
  36. Role of Mn
    Required for activety of some dehydrogenases
  37. Role of B
    Indirect evidence for involvement in carbohydrate transport
  38. Role of Cu
    in protiens that transfer e-
  39. Role of Zn
    essential constituent of alcohol dehydrogenase
  40. Mo
    Essential to N2 fixation
  41. Role of Cl
    Required for the photosynthetic reactions involved in O2 evolution
    • Cortex
    • stele
    • Xylem
    • Pholem
    • Endodermis with casprian strip (real barrier, only pure water through = symplastic flow)
    • Root hair
    • epidermis
  42. Depletion of P with distance from root surface
    • within 3 mm goes down drastically
    • highest rate when ratio is larger
  43. Nutrient Uptake process
    • Transport in Free Space
    • Active uptake- cortex
    • Movement from cortex -> xylem
    • Xylem -> shoot
  44. Transport in the free space of roots
    • 15% of root volume is free space
    • open to free movement of water and nutrients
    • Pectin (-) charge = CEC and holds cations
  45. Movement from cortex -> xylem
    • plasmodesmata- symplastic
    • Diffusion, cytoplasmic streaming
    • Passive (not active)
  46. Transport in the xylem -> shoot
    • Passive
    • Transpiration stream
    • Reloaded in phloem => other sink tissues
  47. Alternative sources of Nutrients
    • Mycorrihiza
    • Recycling
  48. Active Uptake
    • In cortex (w/ epidermis)
    • Takes ATP
    • [] inside cells is much greater than free space
    • carriers (gate keepers)- nutrient specific, requireed nutrients only (some times get K mix with Rb or NH4+)
  49. Mechanism of active uptake
    • ATP synthase pushes H+ outside plasmalemma
    • = apoplast @ 5.5 pH, acidic
    • Then H+ co-transports things in @ high 7-7.4 pH
  50. Kenetic relationship between nutrient uptake rate and external nutrients
    • like enzyme activity
    • add fertilizer to get at max
    • Km = 1/2 max, inverse of affinity
    • If decrease Km - max uptake can suffer
  51. affinity (/Km)
    • high = tight grasp, slow release
    • low= loose grasp fast release
    • Not good all the time, plants have to have an array of many of these
  52. How to ∆ Kinetic factors to increase uptake
    • root elongation, initial [p] from fertilizer, root diameter
    • NOT: the actual factors themselves
  53. Influence of [O] on P uptake by roots
    • at very low it goes way down
    • but otherwise is high
  54. Influence of Temp on N uptake by plant roots
    • @ 25 ˚C linear with time
    • @ 10 and 0 ˚C very very low, almost flat line
  55. Influence of soil water content on nutrient uptake
    much better at wetter soils
  56. Influence of light intensity on nutrient uptake
    high light does better b/c more root growth
  57. Root hair importance
    Unknown
  58. Nutrient recovery v. depth
    fibrous and taproots are similar and get about half from top few inches
  59. Mycorriza
    • P to plants
    • CHO to fungi
  60. Recycling
    • very important in natural systems
    • nutrients from leaves and stems to grain
    • ~20% of what cycles to roots stays
    • ~80% of what cycles to roots comes back
    • During Repro stages, veg donates alot
  61. concentration v. amount
    concentration may be constant but total amount is up because Dry matter up
  62. Grafting
    • used to get best combination
    • Fe control is in roots
  63. Root architecture
    • selection
    • Nutrient placement

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