Lecture 13

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  1. What is Combining Ability?
    the ability of parents to combine amongst each other so that favorable genes/alleles are transmitted to their progenies
  2. What is Specific combining ability?
    • the deviation in performance of hybrids from the expected productivity based upon the
    • average performance of lines involved in the hybrid combination
    •  Differences in SCA are attributed to
    • non-additive genetic variation
  3. What is General combining ability?
    • —the average performance of a line in a series of crosses
    •  Evaluates the additive portion of
    • genetic effects
    •  Difference in GCA are due to additive
    • and additive x additive interactions in
    • the base population
  4. Combining abilitiy concepts:
    •  The higher the GCA value, the better
    • that parent will perform in a myriad of
    • crosses
    •  The higher the SCA, the better hybrid
    • those lines will make
    •  Used a lot in cross-pollinating species
    • where hybrid vigor is desired
  5. Describe Population Improvement:
    •  Population Genetics—change in the
    • genetic structure of a population of plants
    •  Change the gene frequency such that
    • desirable genotypes predominate in the
    • population
    •  Cyclical selection (recurrent selection)
    • increases the frequency of favorable
    • genes
  6. What is Intrapopulation improvement?
    —selection is practiced within a specific population for its improvement for a specific purpose
  7. What is Interpopulation improvement?
    —entails selection on the basis of the performance of a cross between two populations (used for hybrid production)
  8. Describe Recurrent Selection:
    •  Goal-improve the performance of a population
    • with respect to a trait such that the new
    • population is superior in mean performance
    •  Population is improved without the reduction in
    • genetic variability
    •  Population can respond to future improvements
    •  Parents of the cross should be high performing
    • regarding the traits of interest
    •  Parents should not be closely related
    •  More rounds of mating increases the
    • opportunity for recombination
  9. Key Features of Recurrent Selection:
    •  Individual families are created for evaluation
    •  Parents are crossed in all possible combinations
    •  The plants/families are evaluated and new
    • parents selected
    •  The selected parents are intermated to produce
    • a new population for future selection
  10. Describe Ear to Row Selection:
    •  Used to better manage G x E interactions
    •  Genetic gain is both inter and intra family
    • selection
    •  Often used with perennial species
  11. Pros and Cons to Half-sib with progeny test
    •  Advantages
    •  Suited for improving traits of high
    • heritability
    •  Good for plants with self-incompatibility or
    • male sterile
    •  Disadvantages
    •  Based on maternal plant selection, so
    • heritability estimates are reduced 50%
    •  Less effective for low heritability traits
  12. Pros and Cons to Half-sib with test cross:
    •  Advantages:
    •  More precise evaluation of selected plant
    •  Rapid to conduct
    •  Disadvantages:
    •  Must be able to self-pollinate
    •  Need a lot of seed for subsequent progeny
    • trials
  13. What are the general advantages of half-sib methods:
    •  Usually rapid to conduct
    •  Increase frequency of desirable alleles
    •  Progeny/test cross allows a more precise
    • evaluation of the genotype of selected
    • plants
  14. What are the general disadvantages of half-sib methods:
    • Disadvantages-Half-sib methods
    •  In some cases, a lot of seed is needed for
    • subsequent years testing
    •  Trait should have high heritability
    •  Some methods require self-pollination

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Author:
wsucoug12
ID:
317415
Filename:
Lecture 13
Updated:
2016-03-23 03:48:55
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Plant Breeding
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Plant Breeding
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Plant Breeding
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