Lecture 11

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  1. List types of abiotic stress
    • Drought
    •  Heat
    •  Cold
    •  Salinity
    •  Mineral Toxicity
    •  Water-logging
    •  Mineral Deficiency
  2. Describe Stress and Yield Potential
    • Yield is the product of genotype by
    • environment interactions
    •  Any stress can impact plant growth and
    • development
    •  Stress resistance is inherent to all
    • breeding programs
    •  Genotypes must be evaluated at different
    • locations and over years
  3. Screening for Stress Resistance
    • Genetic variation must occur
    •  Heritability of trait should be greater than
    • heritability of yield per se
    •  The trait should be correlated with yield
    •  Screening should be easy, rapid, and
    • economical
  4. Describe Drought Stress
    • Focus on water use efficiency
    •  Yield = Transpiration X WUE X HI
    •  Characterization of drought environment
    •  Indirect selection on traits affecting
    • drought response
  5. Mechanism of Drought Stress
    • Escape
    •  Early maturing to miss drought conditions
    •  Avoidance
    •  Efficient WUE or epicuticular waxes
    •  Tolerance
    •  Continual photosynthesis and partitioning
    •  Recovery
    •  Rebound after drought stress
  6. Traits Affecting Drought
    •  Phenology
    •  Leaf area index, flowering time, maturity time
    •  Plant development and size
    •  Root characteristics
    •  Plant surface
    • Non-senescence (stay-green)
  7. Canopy temperature
    • an indirect measure of Water Use (WU)
    • Transpiration of water cools the plant.
    • Cooler canopies suggest that roots are reaching deeper water allowing them to transpire
  8. Indirect Breeding approach
    •  Genotypes exposed to environmental stresses
    • for selection, but not in the location where
    • stress conditions occur
  9. direct Breeding approach
    • Selection for stress under environments
    • where the conditions are conducive
    • Field Selection
    •  Managed stress environments
    •  Select on yield per se
    •  Select on developmental traits
  10. what is Cold Stress
    •  Multiple classifications for cold stress
    •  Frost-resistant, cold hardy, cold-hardened
    •  Depends on a highly integrated system of
    • structural, regulatory, and developmental
    • genes
  11. Mechanisms for Cold Stress
    •  Chilling resistance
    •  Freezing resistance
    •  Escape
    •  Avoidance
    •  Tolerance
  12. Salinity Stress
    •  Occurs from natural weathering of parent
    • materials
    •  Human-aided salinity occurs from
    • agricultural practices, irrigation, and rising
    • water tables
  13. Breeding Approaches
    •  Tolerance is the best approach
    •  Field screening is effective but a long
    • process
    •  Marker technology is advancing
    •  Resistance more beneficial than tolerance
    •  Field screening under high temperature
    • environments
    •  Control all factors except heat
    •  Controlled environments (growth
    • chambers
  14. Heat Stress
    •  High daytime/high nighttime temperatures
    •  High nighttime temperatures more detrimental
    •  Rice: 4°C increase above threshold = 18% fertility
    •  Warm and cool season plants affected
    • differently
    •  High temperatures tend to accelerate
    • reproductive development
  15. Flood Stress
    •  Most plants need well-drained soils
    •  Breeding is usually done to fit into a
    • specific cropping system
    •  Rice was developed to be flooding
    • resistant
  16. End use quality traits
    • High protein content (and its quality)
    •  High nutrient content
    •  Lysine, Vitamin A, etc
    •  Oil composition
    •  Low phytate (animals produce less methane)
    •  Extended shelf life
    •  Cooking and processing
    • qualities
    •  Seedlessness
    •  Pharmaceuticals
  17. Transgenic Approaches
    • Golden Rice
    •  Gene inserted from daffodil to produce
    • beta-carotene
    •  Agrobacterium used for transformation
Author:
wsucoug12
ID:
316294
Card Set:
Lecture 11
Updated:
2016-03-04 05:48:14
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Plant Breeding
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Plant Breeding
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