lecture 10

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  1. Physiological v. Morphological
    • Physiological—processes common to all plants
    • photosynthesis, translocation, transpiration, leaf angle, water utilization, harvest index
    • Morphological—products of physiological processes
    • Yield, plant height, maturity, flowering date
  2. Yield
    •  Most important aspect of plant breeding
    •  Composed of many important physiological and morphological traits
    •  What traits are these?
  3. What is biological yield?
    the total dry matter produced per plant or per unit area
  4. What is economic yield?
    • the total weight per unit area of a specified plant product that is of marketable value
    •  Corn-both ear and stalk of value
    •  Sugar beet-all plant parts of value
  5. How to enhance yield:
    • Seasonal adaptation
    •  Tolerance to adverse environmental factors  Pest and Disease resistance
  6. What are the components of yield?
    •  Can be difficult to breed directly for yield  Components are easier to select for
    •  Plants per unit area
    •  Tillers per plant
    •  Number of ears per plant
    •  Number of seeds per ear
    •  Compensation can occur in some circumstances
    •  Wheat and tiller number
  7. What is Yield Potential?
    the inherent optimum capacity to perform under a given environment
  8. What is Yield Stability?
    no G x E interactions
  9. What does yield plateau?
    •  Less focus on yield and more on disease resistance
    •  Increases in fertilizer prices
    •  Genetic potential is present
  10. What is Lodging resistance?
    • resistance to leaning, bending, or breaking of the plant prior to harvest
    •  Short stature
    •  Stronger, thicker stalks,
    •  Resistance to stalk/stem pests
    •  Recurrent Selection
    •  Molecular markers
  11. What is Shatter Resistance
    • Shatter-fruits split open upon maturity and discharge their seeds
    •  Advantageous in the wild, not in cultivation
    •  Of high economic importance
    •  Breeding is often done by visual selection  Also subject to environmental conditions  Hail, wind, etc.
  12. Why is reduced plant height desirable?
    • Reduced stature increases harvest index
    •  Less straw desired only in some instances  Selection mainly done visually
    •  Genetics fairly well understood in many crops
    •  Played role in the green revolution
    •  GA sensitive and insensitive types
  13. Long-day plants:
    • require a light period longer than a certain critical length in order to flower
    • Wheat, barley, alfalfa, sugar beet
  14. Short-day plants:
    • —require a photoperiod of less than a certain critical length
    •  Corn, rice, soybean, peanut, sugarcane
  15. Day-neutral:
    • plants will flower regardless of the duration of day length
    •  Desirable when producing crop over latitudes
  16. Photoperiod Response:
    •  Need plant to flower at the correct time to maximize yield potential
    •  Genetics highly understood
    •  Breeding done both visually and with markers
    •  Need a firm understanding of the environment one is breeding for before selecting for photoperiod response
  17. Breeding for Resistance:
    •  A high priority for many breeding programs  Yield potential can never be reached if pests are a limiting factor
    •  Various breeding methods and strategies have been developed
    •  Main disease will vary greatly by type of crop one is breeding for
  18. Disease Biological and Economic Effects:
    •  Complete plant death
    •  No economic return and weed issues
    •  Stunted growth
    •  Typical of viruses
    •  Partial plant death
    •  Usually when adult plants are attacked
    •  Direct product damage
    •  High economic damage
  19. Disease control methods:
    •  Exclusion of the pathogen from the host
    •  Reduction of the pathogen’s inoculum
    •  Improvement of host resistance
    •  Protection of the host  Chemicals
  20. Disease Concepts:
    •  Pathogenecity The capacity of the pathogen to cause a disease
    •  Virulence The extent of disorder or disease development
    •  Disease triangle Pathogen—Host—Environment
  21. Plant disease defense:
    •  Pre-existing defense mechanism
    •  Morphological features that post as barriers  Secondary metabolites
    •  Infection-induced defense mechanism
    •  Upon infection host produces chemical products
  22. Plant disease defense Avoidance:
    •  Reduces the probability of contact between pathogen and host
    •  Time of planting
    •  Morphological traits
    •  Allelochemicals
    •  Odors
  23. Plant disease defense Resistance:
    •  Manifests after the host has been attacked by the pathogen
    •  Passive resistance—mechanism is preexisting
    •  Active resistance–the mechanism is induced
    •  Hypersensitive reaction-prevents pathogen establishment
    •  Overdevelopment of tissue-excessive abnormal growth such as galls or leaf curling  Underdevelopment of tissue-afflicted part becomes stunted or underdeveloped
  24. describe tolerance:
    •  Ability of plant to maintain economic yields while under attack from pest
    •  Plant vigor
    •  Rapid root growth
    •  Photosynthate partitioning
  25. What is Vertical Resistance
    •  Race or pathogen specific
    •  Single gene or qualitative resistance
    •  Typically absolute in reaction
    •  Typically termed non-durable resistance
  26. What is horizontal Resistance
    •  Race-non-specific
    •  Multiple genes/minor genes (quantitative)  Minor gene reactions
    •  Typically termed durable resistance
  27. Resistance Breeding Strategies I:
    •  Breeders typically only focus on pests of major economic importance
    •  Ease and level of success varies greatly
    •  Consistency in screening of high concern  Instability of pest may require constant selection of new resistance mechanisms
    •  Must justify breeding for pest (the process is long and expensive)  Natural resistance is not always available  Level of success varies from one pest to another (foliar pathogens easier than root pathogens)
    •  Instability of pest resistance modifies the host (it is what keeps us in business)
  28. What are multilines:
  29. Resistance Breeding Strategies II:
    •  Gene pyramiding
    •  Planned release of resistance genes
    •  Multilines
    •  Breeding with vertical resistance
    •  Combining vertical and horizontal resistance
    •  Role of wild germplasm
  30. Resistance Breeding Procedures:
    •  Identification of resistance genes
    •  Either through literature or own efforts
    • Transfer of these genes into germplasm
    •  Backcross, forward breeding, markers
    •  Consistent reliable screening
    •  Field screening, greenhouse screening
    •  Selection

Card Set Information

Author:
wsucoug12
ID:
316571
Filename:
lecture 10
Updated:
2016-03-02 05:33:30
Tags:
plant breeding
Folders:
plant breeding
Description:
plant breeding
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