Lab 2

• embryo: the new plant generation, the product of fertilization
• storage reserve tissue: sustains the germinating embryo until the seeding can produce its own resources
• Dicto storage reserve tissue is contained in the endosperm, cotyledons, and perisperm tissue
• Monocot storage reserve tissue is in the endosperm
• protective outer covering: surrounds the seed and provides physical protection
• fleshy seed: fleshy layers attached
• dry indehiscent seed: doesn't split open when ripe to release seed (nuts)
• dry dehiscent seed: split open when ripe to release seed (legumes)
• seed tests:

  • purity analysis
  • noxious exam
  • germination test
  • viability test (TTC)
  • vigor test
• viability tests: measure the number of seeds that are still alive to produce plants
• cut test: cut seed and observe if there are malformations
• float test: non-viable seeds float and viable seeds sink
• Tetrazolium Chloride (TTC) test: stains living tissue and indicates viable seeds
• TTC contains dehydrogenase
• germination: the emergence and development from the seed embryo of those essential structures which, for the kind of seed in question, are indicative of the ability to produce a normal plant under favorable conditions
• methods of planting:

  • planting boards
  • vacuum planters
  • hand planting
• root functions:

  • anchor plant in soil
  • absorb water & dissolved salts from soil
  • conduct water & salts to hypocotyl, cotyledons, and epicotyl
• hypocotyl: portion of seedling axis between the root and the cotyledons
• cotyledons in dicots: storage structure of the embryo
• epicotyl: includes all seedling structures above the cotyledons
• terminal bud: at tip of epicotyl, the apical meristem
• Seedling structure of dicots and gymnosperms:

  • root
  • hypocotyl
  • cotyledons
  • epicotyl
  • terminal bud
• cotyldeon in monocots: absorbs nutrients from the endosperm and transfers them to growing seedling
• coleoptile: present only in Poaceae; protective sheath enclosing terminal bud and developing leaves
• plumule: first leaf
• seedling structure of monocots:

  • root
  • hypocotyl and mesocotyl
  • cotyledon
  • coleoptile
  • plumule
• Sexual propagation results from the germination of either seed or spores
• Seeds are made of 3 necessary parts: the embryo, the endosperm, and the testa (seed coat)
• Embryo is the plant that will eventually result from the germination of the seed
• The endosperm is the energy source (protein, carbs, and lipids) for the embryo during the dormancy period
• The testa is a protective barrier for the embryo
• Ovary at the base of the flower swells when fertilized
• During double fertilization, pollen from one flower lands on another flower and the pollen grain germinates and a pollen tube goes to the ovary. The pollen tube allows two sperm cells into the ovule
• Double fertilization results in a triploid
• All seed experience a stage of tissue differentiation and cell expansion but not all seeds go through maturation drying
• If a seed is an orthodox seed, it will go through maturation drying and will be dried down to 10-15% moisture
• For long term storage, moisture of 8% is best
• Recalcitrant seed is unable to withstand drying
• viability tests:

  • cut test
  • float test
  • TTC test
• cut test: cut seed in half and observe whether the endosperm is fully formed