Plant breeding lecture 9

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  1. How to choose parents for a breeding program
    • From this, genetic variation is created
    • Evaluate strengths and weaknesses
    • Evaluate adaptability over environments
    • Evaluate combining ability
    • Agronomic Traits
    • Yield Potential
    • Disease Resistance
    • End-use Quality
  2. Where are sources of germplasm?
    • Current breeding program
    • Regional breeding programs (public and
    • private)
    • International breeding program
    • Landraces
    • Wild relatives
  3. adapted by adapted example of parent selection:
    • Don’t worry much about traits such as time to
    • flower, maturity, plant height, etc
    • Focus in on traits of most importance
  4. Adapted by unadapted example
    • Adapted by Unadapted
    • Focus in on the best of the adapted lines
    • Agronomic traits start to become more of an
    • issue
  5. How to decide on which traits to select for?
    • Traits seen easily in the field
    • Heritability of trait
    • Availability of molecular markers
    • Importance of trait
    • Ease of testing (end-use quality)
  6. how to screen/Identification Traits
    • Easily screened and highly heritable
    • Can screen in earlier generations
    • If predictive, negative selection occurs
    • Easily screened and low heritability
    • Usually screen later in the breeding process
    • (or for multiple rounds)
    • Importance of trait will determine how many rounds of selection will need to occur
  7. Identification of Traits that are hard to screen for:
    • Hard to screen and low heritability
    • Will be done mid to late generations for
    • selection (might need a couple of rounds of
    • selection)
    • Will look for the use of molecular markers
    • Will need larger population sizes
  8. When to use markers to screen for a trait?
    • Trait very difficult to screen for and high on
    • breeding objectives
    • Biasing populations in favor of a trait
    • Need for pyramiding multiple genes into one
    • genotype
  9. Identification of traits hard to screen for and highly heritable:
    • Hard to screen and highly heritable
    • Will be done in late in selection process
    • Again depends on importance of trait and
    • resources of group
  10. Early Screening methods:
    • Inexpensive
    • Small amount of material
    • Non-destructive
    • Indirect measures of performance-negative
    • selection
  11. Late screening methods:
    • Expensive
    • Large amounts of seed/fruit required
    • Often destructive
    • Direct measures of performance-Positive
    • selection
  12. Describe Early screening:
    • Early Generation
    • –Number of entries is higher
    • –Small quantity of seed required
    • –Low genetic variance between entries
    • - More difficult to distinguish between
    • genetic and random effects
    • –Space and labor requirements higher
    • –Can eliminate poor performing entries
  13. Describe Late screening:
    • • Late Generation
    • –Smaller number of entries
    • –Labor requirements still high
    • –Positive selection for elite lines
    • • Have eliminated poor performing lines
    • –Multiple location testing
  14. Outline experimental design:
    • Needs to fairly and effectively evaluate
    • genotypes in the field
    • Needs to be done in an environment similar to
    • that of the farmer
    • Need to limit environment to best evaluate
    • genetic performance
    • Evaluation must be error free
  15. Sources of error in experimental design:
    • Treatments—impose conditions that generate
    • variance in outcomes
    • Units may be plots, rows, single plants, etc
    • Experimental Error is the variation among
    • plots that are treated alike
    • Soil (site) variability
    • – Soil minerals
    • – Soil moisture
    • – Organic matter
    • – Topography and slope
    • – Crop rotation/previous crop
  16. How to reduce error in an experimental design with border rows:
    • Use of border rows
    • – Competition from outside the plot area
    • – Interplot competition
    • – Data collected on middle rows only
  17. How to reduce error in an experimental design with plot size and shape:
    • Plot size and shape
    • – Dependent upon objectives, stage of breeding,
    • resources available, equipment
    • – F2 based on individual plant performance so
    • plants must be space planted to allow for
    • evaluation
    • – Mico/mini-plots—inexpensive way of eliminating
    • the inferior genotypes
    • – Many time rectangular in shape
  18. How to reduce error in an experimental design with replications:
    • Adequate number of replications
    • – Replications is critical for statistical analysis
    • – Usually 2-4 replications
    • – No replications often used in early generations (dangerous!)
    • – Number of replications depends on accuracy desired
  19. How to reduce error in an experimental design when using humans:
    • Minimize operator errors
    • – Human error
    • – Must manage and treat uniformly
    • – Data collection must be accurate
    • – Mistakes must be accounted for and dealt with
  20. Experimental Design contin:
    • Replication—critical for estimating
    • experimental error
    • Randomization—Eliminates bias in the
    • estimation of treatment effects
    • Local control—Use of a known genotype to
    • standardize results
  21. Describe Plot Designs (single plants):
    • No design arrangement
    • – Usually done in segregating populations
    • – Advantages:
    • – Inexpensive and easy (large number of genotypes)
    • – Limitations:
    • – Environmental variations
    • – Suitable for traits with high heritability
  22. Describe Unreplicated Plot Designs (multiple plants):
    • Unreplicated
    • – Planting single rows or plots for evaluation
    • (usually designed to eliminate inferior genotypes)
    • – Advantage:
    • – Save space and are less expensive
    • – Large number of genotypes quickly evaluated
    • – Disadvantage:
    • – No replications!
  23. Describe replicated Plot Designs (multiple plants):
    • Replicated
    • – Randomization important here
    • – Complete block—small number of entries, each block contains all entries
    • – Incomplete block—large number of entries, genotypes split between blocks to account for variation
    • – Advantage:
    • – Can account for environmental variation
    • – Disadvantage:
    • – Can be limited by # of entries and statistics

Card Set Information

Author:
wsucoug12
ID:
315972
Filename:
Plant breeding lecture 9
Updated:
2016-03-04 00:50:47
Tags:
plant breeding
Folders:
plant breeding
Description:
plant breeding
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