Seed Production and Handling

• dioecious: male and female flowers on different plants
• monoecious: different male and female flowers on the same plant
• dichogamy: the separation of male flower function in time; pollen shed at different time than pistil is receptive
• protogyny: female becomes receptive before the male sheds pollen
• protandry: male sheds pollen before the female is receptive
• polymorphism: different arrangements of flower parts in flowers from the same or different plants within the same species
• sexual incompatibility: the inability of the plant related to produce offspring; genetic barriers to successful pollination or fertilization between plants
• self-incompatibility: a form of sexual incompatibility; lack of pollen growth or restricted pollen tube growth
• gametophytic incompatibility: each pollen grain has a single S-allele; pollen tube will not grow down a style where the allele is represented
• sporophytic incompatibility: each pollen contains genes of both S1 and S2 alleles and the pollen tube will only grow down a style with a different genotype
• You can control genetic variability through:

  • isolation
  • roguing
• isolation methods:

  • distance
  • enclosing in cages
  • removing male flower parts
• roguing: removal of off-type plants, plants of other cultivars and weeds in the seed production field
• seed production system phases:

  1. development phase
  2. maintenance phase
  3. multiplication or distribution phase
• development phase: production of a small quantity of seeds (breeder's seed) that is maintained by the originating institution as the primary reference for the cultivar
• maintenance phase: a quantity of seed (foundation or stock seed) is maintained under high standards of isolation, inspection, and roguing
• multiplication or distribution phase: a second generation increased block and a third generation block to produce commercial seed for distribution to the public
• seed certification: a legalized program that applies the previously mentioned principles to the pedigree seed production of specific seed-propagated plant cultivars to ensure the maintenance of seed purity
• seed certification objective: provide standards to preserve the genetic qualities of a cultivar
• seed certifying agency: determine production standards for isolation, maximum percentage of off-type plants and quality of harvested seed, make regular inspections of the production fields to see that the standards are being maintained and monitor seed processing
• commercial seed production: agricultural, vegetable, and flower seed production
• Some agricultural seeds are produced in the area where the crops are grown. This reduces the transportation and handling costs and the potential for genetic shift.
• Some seeds are produced in specialized growing areas. This provides the best conditions for producing high-quality, disease-free seeds which leads to high-value crops.
• major considerations for selecting areas for seed production:

  • environmental conditions
  • cost of production
• biennials:

  • vernalization
  • overwintering
• vernalization: a period of cold temperature required by plants to induce flowering
• Overwintering in fields or putting stecklings into a cooler shortens the seed production cycle.
• stecklings: one-year-old biennial plants used for seed production
• appropriate site for high-quality seed production:

  • low summer rainfall
  • low humidity
  • limited rainfall during seed harvest season
• considerations for site selection:

  • soil type and fertility
  • cropping history to avoid disease or herbicide carryover
  • adequate soil moisture or irrigation
  • dry environment during seed harvest
  • ability to isolate open or cross-pollinated crops
• considerations for high-quality seed production:

  • appropriate site
  • appropriate planting density
  • pest control
  • availability of insect pollinators
• mature/ripe: used to describe the fruits that ripe on the plants known as non-climacteric
• horticultural maturity: any stage of development when the fruit has reached a level of development sufficient for its intended use
• horticultural maturity:

  • indicate desirable changes to make it marketable
  • may not ripen
  • maximum growth and maturation may not have occurred
  • seed collection is not easy
• physiological maturity: the stage in the development of fruits when maximum growth and maturation has occurred
• physiological maturity:

  • indicate the end of the stage
  • maximum growth and maturation occurred
  • may ripen after harvest
  • seed collection easy
• physiological harvest maturity: the time during seed development when seed can be harvested for germination without a significant reduction in seed quality
• If you harvest too late, fruit may dehisce, drop to the ground, or be eaten/carried off by birds or animals
• If harvested too early, embryo may not be fully developed and seed may be poor quality
• Seed moisture percentage is an indicator of seed maturity