Historical Background

  a. Seed quality prior to 1950

  b. Role of seed in agricultural development

Development of the Seed Industry

 a. Factors

    1. New varieties

       - Hatch Act (1875)

       - National Foundation Seed Project (1949)

    2. Development of seed certification. & enforcement programs

    3. Development of seed technology

    4. Knowledge of seed quality

    5. Emergence of seed industry

Genetic Principles

• Variation
  1. Genetic
  2. Environmental
• Genetic Control
  1. Monogenic
  2. Polygenic
     • Quantitative (continuous)
     • Qualitative (noncontinuous)
• Deterioration of Genetic Purity
  • Factors responsible for deterioration
    1. Developmental variations
       • Different soil types, fertility, climate, photoperiods or elevations
    2. Mechanical mixtures
    3. Mutations
       • Typically not an important factor
    4. Natural crossing
       • More serious in cross-pollinated crops
       • Principle effects:
         1. Undesirable plants
         2. Diseased plants
         3. Off-type plants
    5. Minor genetic variations
       • Phenotypic variation
    6. Selected influence of diseases

Maintaining Genetic Purity of Seed

• Key steps involved:
  1. Use certified seed
  2. Inspect plot area before planting
  3. Maintain adequate isolation from similar crop cultivars
  4. Inspect fields during critical growth phases:
     • Vegetative
     • Flowering
     • Maturity
  5. Sample and seal seed lots
  6. Compare seed samples with authentic stock

Agronomic Principles for Seed Production

• Agroclimate and Location
  • Variety must be adapted to photoperiod and temperature conditions
  • Area should have dry period and moderate temperatures during flowering & at maturity
• Isolation, Variety and Sowing
  • Maintain appropriate isolation
    • AOSCA standards (minimum)
  • Consider seed treatment
  • Seed rate
    • Typically less than commercial rate for early generations
• Roguing, Pollination and Weed Control
  • Rogue diseased plants, off-types and other crops
  • Supplementary pollination
  • Weeds harbor diseases and insects
    • Harvest problems
• Irrigation and Plant Nutrition
  • Crops are most moisture sensitive in vegetative, flowering & maturity
    • Fertilizer quantity and timing
      • N: top growth
      • P: root growth, straw strength, fruiting & seed development
      • K: photosynthetic efficiency, protein & lipids in oilseeds       
• Plant Protection
  • Appropriate fungicides and insecticides
  • Rogue diseased plants
• Harvesting, Drying and Storage
  • Best harvest moisture content:
    • Wheat = 15 - 17%
    • Soybeans = 13%
  • Drying seed temperature <105^oF

Production Area

• Local
  1. Economics
  2. Logistics
• Outside of Area
  1. Advantages
     • Climate
     • Insects
     • Diseases
  2. Disadvantages
     • Cost
     • Genetic Drift

Legume Seed Production

• Western Areas
  1. Advantages
  2. Disadvantages
• Cultural Practices
  • Row spacing
  • Seed rate
  • Weed control
• Insect Pollinators
  • Honeybees
  • Leaf-cutting bees
  • Alkali bees
  • Bumblebees & Melissodes bees

   Grass Seed Production

• Cool Season Grasses
  • Characteristics
  • Adapted to northern areas
  • Grow actively with cool temperatures
  • Become dormant with hot temperatures
• Cultural Practices
  • Row spacing
  • Seed rate
  • Weed control
  • Harvest
  • Disease & Insect control
• Warm Season Grasses
  • Characteristics
  • Great Plains Grasses
  • Southern Grasses

References:

Principles of Seed Science and Technology. 3rd Ed. L.O. Copeland and M.B. McDonald. Chapman and Hill, New York, 1995.

Seeds Handbook, B.B. Desai, P.M. Kotecha and D.K. Salunkhe. Marcel Dekker, Inc., New York, 1997.