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The Seed Notes. 8 th Grade Exploring Agriculture New Lisbon Agricultural Education Department. Seed Characteristics. Viable Taken from strong healthy parent plants Collected and handled correctly. Collect seed from local plants. Order seed from suppliers. Quality Seeds. Sources of Seeds.
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The Seed Notes 8th Grade Exploring Agriculture New Lisbon Agricultural Education Department
Seed Characteristics • Viable • Taken from strong healthy parent plants • Collected and handled correctly • Collect seed from local plants. • Order seed from suppliers Quality Seeds Sources of Seeds
Pollination, Fertilization and Germination. • Pollination • The transfer of pollen from an anther to a stigma of a flower of the same species. • Fertilization • The union of the pollen and ovule cells. • Germination • The sprouting of a seed. • Self-Pollination • Pollen from a plant pollinates a flower on the same plant • Cross-Pollination • Pollen from a plant pollinates a flower on a different plant
What are the parts of a seed? • Seed coat • Protective covering around the seed. • Hard surface that protects the interior of a plant. • Embryo • The new plant that has developed as a result of fertilization. • During germination it extends its roots and seed leaves to form a new plant. • Endosperm • Provide energy for embryo and young plant. • It supplies enough energy for the plant to grow until the leaves start to produce energy.
Embryo: • The miniature plant that forms from the union of the sex gametes. • Plumule: • 1st terminal bud • Develops into the first shoot that emerges from the seed.
Hypocotyl: • 1st true stem • Causes the plumule and cotyledons to emerge from the seed. • Radicle: • 1st root of the plant • 1st to emerge from the seed
Cotyledons: • 1st leaf or leaves that emerge from the seed. • They fall off after the 1st true leaves form.
Germination • Germination: the development of a seed from a resting stage to a stage of growth.
Seed dormancy • Seed Dormancy: • A protective condition that prevents the seed from germinating until all of the environmental factors required for optimum growth are present.
Why will some seeds not germinate right after ripening? • Some seed coats are too thick or extremely hard to allow moisture into the embryo. • Some seed coats contain a chemical inhibitor that must be washed away.
Scarification & Stratification • Scarification: • The scratching or removal of the seed coat to induce germination. • Sandpaper • Removal of an end of the seed • Create a crack in the seed • Soak in sulfuric acid • Must be washed several times after soaking in sulfuric acid. • Dried • Stratification • Putting seeds in moist cold conditions to stimulate germination.
Conditions required for seed germination • Water absorption • The seed does not need to be submerged in water, just moist. • The water softens the seed coat. • Causes the embryo to release the hormone gibberlin. • Gibberlin activates digestive enzymes that cause the release of cytokins & auxins. • Cytokins and auxins induce cell elongation and cell division.
Conditions required for seed germination • Moisture • Too much water causes the plant to rot. • Too light water causes the plant to dry out and die. • Water drives many of the reactions in the plant. • Photosynthesis, respiration, nutrient uptake and nutrient transport • Intermittent Low-Pressure Misting • Controlled by a • Time clock • Solar-activated counter • Electronic leaf • Sub irrigation • Seed flats are soaked with water from the bottom. * Applied only during daylight hours because of disease and lower temperature caused by evaporative cooling of the water
Conditions required for seed germination. • Oxygen Supply • Needed for respiration • Light • Affects germination • 4 types of light responsive plants • Full light • Half light/ half dark • Full darkness • No affect either way • Red wavelengths have the most influence on germination • Far-red light become “leggy”
Conditions required for seed germination. • Temperature • Minimum: point at which seed will not germinate • 32-39 • Optimum: desired level for most species • 68-86 • Maximum: point at which seeds will not germinate • 113-120 • Temperature • Plants have an optimum temperature for growth • Bottom heat (5-10 higher than the air temperature) helps expedite germination • Heat should be removed once germination occurs because the plants become too succulent (soft) and “leggy” and does not transplant well.
Germination media requirements and components • Requirements • Not too heavy • Contain small amount of nutrients for plant growth • Free of all pathogens or weeds • Holds water, but allows aeration and drainage (porosity) components
Ideal germination environment • Aeration • Must have enough air for respiration • If the soil is too hard (no pore space), water retention will be dramatically reduced