AGRY 525 Exam I

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Author:
MRK
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262059
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AGRY 525 Exam I
Updated:
2014-02-19 12:58:09
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Photosynthesis Respiration Volenc
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  1. How do night time temperatures affect yield?
    • High temps = Rd ^ = yield down
    • Low temps = Rd down = yield ^
  2. Fick's Law
    • Rate of diffusion ~ ∆concentration/∆distance
    • ∆c/∆d
  3. affects of Still air v. windy air around corn plant on photosynthesis
    • [CO2] @ 500m = 400ppm
    • [CO2] @ leaf surface = Still 200ppm, Windy 400ppm
    • ∆d gets much smaller = rate of diffusion
  4. What is N used for in plants
    Protiens
  5. What is P used for in plants
    • ATP
    • NADPH
    • PGA (phosphorylated sugars)
  6. What is K used in plants for
    opening and closing stomata
  7. what is Mn used in plants
    e- extraction from H2O
  8. Cu role in plants
    in light rxn
  9. S role in plants
    light rxn
  10. Fe role in plants
    light rxn
  11. The formula
    Ps-Rd = growth + stored reserves
  12. General Stored reserves
    • No Ps when (hot, dry, cold)
    • Survives on stored reserves
    • Irreversible CHO Storage (seeds)
    • Reversible Storage
  13. Where do Annuals store CHO
    • Grasses: lower 1/3 of stem
    • Dicots: Roots
  14. Where do Biennials store CHO
    • Yr 1 - Veg devo and C stored
    • Yr 2 seed production and no storage
    • eg sweet clover = blood thinner
  15. Where Do Perennial Grasses store CHO
    • 'stem base' (leaves/stem together, more leaves on younger) 3-4" above soil
    • stems: may and june
    • Rhizomes- below ground stem
    • Stolons- above ground stem
    • Corms- swollen internodes (timothy)
  16. Where do Perennial Dicots store CHO
    • Taproots: carrots
    • Stolons: white clover
    • Rhizomes: not many (Kura clover)
  17. What kind of CHO compounds do plants store
    • Sugars
    • Polysaccharides (Starch, Fuctans)
    • Lipids
    • Protiens
  18. Stored plant sugar
    4
    • 4 kcal/g of material
    • Sucrose: non-reducing sugar, inert
    • C4 annuals are the main plants (corn, sorghum, millet)
    • Also sugarcane and sugar beet
  19. Stored Plant starch characteristics
    • Polymer of glucose
    • 4 kcal/gram
    • amylose 20%
    • amylopectin 80%
    • Not water soluable
    • Stored in plastids called amyloplasts
  20. Amylose
    • Starch
    • linear glucose
    • DP (degree of polymerization) = 3,000
    • used to coat paper
  21. Amylopectin
    • starch component
    • branched glucose chain
    • DP= 500,000
    • why corn starch gels
  22. Plants that store starch
    • C4 perennial grasses: zoysia, bermuda, miscanthus, switch grass, big blue stem
    • Legumes: alfalfa, sweet clover, red clover, white clover
  23. Fructans
    • Polymer of fructose (a polysaccharide)
    • 4 kcal/g
    • small DP= 3-300
    • soluble in water
    • cool season C3 (tall fescue, KY blue grass, orchard grass, wheat, barley, oats, rye, onion, Jerusalem artichoke, chicory)
  24. lipid storage in plants
    • 9 kcal/g
    • seeds
    • small volume
    • synthesis takes much more energy than CHO
  25. Plant proteins
    • 4 kcal/g
    • very expensive to synthesis
    • N source- not N
    • Vegetative storage protiens
    • clover canopy
    • bad structure
    • not all leaves involved
    • gets bet out for light
    • survives b/c N fixation
    • Grass canopy
    • almost all tissues intercepting light
    • taller than clover
    • good canopy structure
  26. C4 discovered in
    1966
  27. C4 temperature
    • pretty bad lower than 10C/50F
    • Optimum 30+/- 5
  28. C3 temperature
    • Broad temp optimum
    • 10-20C
    • can still photosynthesis until ice forms
  29. both really decline when low
  30. Temperature affecting C3
    • If no photorespiration and do really good at high temp
    • Peak moves higher without
  31. When do plants fluoresce
    Spell Fluorescence
    • when light rxn screwed up
    • fluoresce to get rid of energy
    • atrizine stops e- passing = fluoresce and die
  32. around 20C how does temp ∆ dark respiration
    • as temp goes up Rd rate doubles
    • Q10=2
  33. H2O // CO2 exchange at leave ratio
    more H2O lost than CO2 in
  34. Water Stress on Photosynthesis
    • growth is stopped
    • Ps not affected until mod stress
    • drops off gradually as stomata close
    • Stops at abrupt closure
    • *Soybeans can get CO2 through cuticle
  35. Relationship btw leaf conductance and photosythsis
    • As stomata open Ps increases
    • If water limiting can partially close stomata- levels out Ps but cut water loss
  36. WUE
    • water use efficiency
    • kg H2O / kg Dry Matter
    • alfalfa 1500:1
    • Partial stomata closer helps this
  37. ratio of Ps to Rd when under stress
    Rd >> Ps
  38. current CO2 concentration
    • ~400 ppm
    • winter goes up
    • summer down
  39. Influence of [CO2] on leaf Ps of C3 & C4
    • C4- no bump with increase
    • C3- Photorespiration will go down @ 800 ppm CO2 will beat C4
  40. Influece of [CO2] on growth on C4 & C3
    • C4 don't respond to increase
    • C3 respond and grow more
  41. Ps of C4 and C3 with [O2] ∆
    • C4: no impact
    • C3: goes down with increase
    • 2% O2 inhibits Photorespiration
  42. Influcence of wind speed and leaf size on boundary layer thickness
    • big surface w/ slow wind = thick boundary layer
    • thinner boundary layer as speeds go faster
  43. PEP carboxylase is how much of protein in C4s?
    15%
  44. Influence of leaf [N] on Ps in C4 v. C3
    • C4 responds better
    • both increase
  45. C4 or C3 is more efficient on K use
    C4
  46. Where are buds from tap root?
    below the surface
  47. Non-structual CHO in alfalfa during season
    Ps - Rd = growth and stored resese
    • April: 0 - + = Up + down
    • Late may: +++ - + = up + up
    • August-cut: 0 - + = up + down
    • need 155% of april to make it thorough winter
  48. N2 Fixation throughout season
    • @ 100%
    • cut = drop to 0
    • for 2-3 wks fixation at zero
    • then sharp increase
    • N stored in taproots: gradually comes down then merges with fixation on the up
  49. Annuals stored reserve for grain growth
    • straight line regardless of Ps
    • Use stored reseves
    • fill seed at all costs
  50. Cutting Alfalfa
    • Cut close
    • Not often
    • will end up at the same level
    • if every 2 wks- will deplete stored reserves and die
  51. Birdsfoot Trefoil
    • Poor seedling vigor
    • doesn't cause bloot
    • effictively no stored reserves
    • Needs to be cut high
    • can be cut often
    • photoperiods and cool = start storing
  52. Seasonal change in root N and protein in legumes
    • Accumulates a lot in the fall (especially alfalfa)
    • Goes down in spring for initial growth
    • then up and down like in other charts
  53. N transfer values from storage for Rye grass
    • 55% from stem base
    • 47% roots
  54. N transfer values from storage for Alfalfa
    • 41% from crown leaves and stem
    • 78% from taproots
    • 52% from lateral roots
  55. N transfer values from storage for White Clover
    • 70% from stolons
    • 56% from roots
    • Biennial
    • year 1 mange like alfalfa (close, not often)
    • Year 2 like Birdsfoot (often, not close)
    • Don't want to cut in critical fall period
  56. Influence on defoliation on kernel dry wight in corn
    • Ps is taken out of the model
    • Rate is slightly reduced but still linear
  57. Influence of light intensity on restoration of nonstructural CHO in Alfalfa roots
    • Takes longer in a low light environment to build back up
    • doesn't ever make as much as high light
  58. Influence of temperatuer on CHO restoration in stem base of rye grass
    • @ high temp: high Ps, low Rd = CHO up and storage happens
    • @ low temp: drecase Ps, high Rd thus low CHO and growth
    • NB: C3 fructan storage
  59. Influence of Stored reserves and leaf area on regrowth rate in Orchard grass
    More important to have stored reserves than leaves
  60. How does N/P affect equation and lodging
    • Ps up
    • Rd ~
    • growth ^^
    • S.R. goes down
    • 28% lodging
  61. How does NPK affect equation and lodging
    • Ps ^^ (stomotal control)
    • Rd ~
    • Growth ^
    • SR down little
    • 1% lodging
  62. Affect of K on sugar mobilization in corn
    If K added less of a drop in sugar
  63. Influence of N fert on leaf N, stubble N and yield
    • More N =
    • more leaf N
    • less stubble N
    • More yield
  64. Lodging Resistance
    • Stem breakage = low CHO reserves in stem
    • High K: prevents / limits lodging
    • High N (P): can some times increase lodging
  65. N affect on equation
    • Ps ^
    • Rd ^ (more maintenance)
    • Growth way up
    • S.R. Down

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