Sexual Propagation Mr. Wilson Uintah High School
Objectives Students will describe the elements of propagation and the techniques and practices used for propagation. • Define Propagation. • List the two main types of plant propagation. • Define germination. • Identify the life cycle of plants. • Identify the parts of a seed.
Objectives Continued • Define seed dormancy. • Explain why some seeds will not germinate right after ripening. • Define scarification. • Identify the factors affecting germination.
Objectives Continued • Identify germination media requirements and components. • Explain the ideal germination environment. • Identify the proper steps in transplanting a seedling.
Plant propagation is reproducing, or increasing the number of plants. Either sexually or asexually. What is plant propagation?
What is sexual reproduction? • Sexual propagation requires the union of the pollen (the male sex cell) and the egg (the female sex cell). • The union of the female and male sex cells to produce a seed (embryo). • Ovule: female sex cell. • Pollen: male sex cell. • Embryo (seed-germ): an immature plant. • *Sexual reproduction involves the creation of a genetically new individual.
List and explain the different types of seeds. • Monocots: • Seeds with one seed leaf. • Leaves have parallel veins. • 1 solid seed. • Stem vascular bundles scattered. • Roots are adventitious • Flowers in multiples of three. • Pollen with single furrow or pore
Dicots • Seeds with 2 seed leaves or 2 cotyledons • Veins are “webbed.” • Pollen with three furrows or pores. • Flowers parts in multiples of four or five. • Stem vascular bundles in a ring.
List and explain the different types of flowers. • Complete • Incomplete
Complete Flowers Have all four major parts; sepals, petals, stamen and pistil.
Complete Flowers • Sepals • The outer part of the flower. • In open flowers, the sepals are found at the base of the plant.
Stamens • The male part of the flower that has an anther at the end of it to produce pollen.
Pistil • Stigma • The opening of the pistil. • Style • The tube-like structure that connects the stigma and ovary. • Ovary • The site of fertilization and growth of the seed.
Incomplete Flower • An incomplete flower is one that lacks one or more of the four principal components identified in a complete flower.
Explain the difference between a perfect and imperfect flower • A perfect flower is one with both the stamen and pistil • An imperfect flower is one that lacks one of the sex organs.
Define 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.
What are the parts of a seed? • Seed coat - protective covering around the seed. Hard surface that protects the interior of a plant. • Comprised of two coats • Testa: outer layer • 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.
For what reasons are plants produced from seed? • May be the only way to reproduce certain plants • Only way to produce new varieties • Sometimes less expensive than other methods • Sometimes quicker than other methods • Only way to attain plants with hybrid vigor
What are the characteristics of quality seed? • Viable – ALIVE! • Taken from strong healthy parent plants • Collected and handled correctly
What are the sources for seed? • Collect seed from local plants. • Order seed from suppliers • Utah and Federal Seed Acts • Seed laws to protect consumers • Seed test dates, viability, germination, purity Note – Always buy seed from a reputable source!
Direct seeding vs. Indirect seeding • Direct seeding - seed is sown directly into the container (or ground) in which it will be grown. • Indirect seeding - seed is sown into one container and later transplanted into a larger container or planted in the ground.
How do I plant a seed? • Fill container with a quality growing media • Moisten growing media • Make a depression or hole into which the seed can be sown. • Place seed into hole/depression. • Cover seed if needed. • Make sure soil Temperature is warm enough. • General rule of thumb - Plant seed at a depth of 1.5 times its length and cover if needed. • Note: some plants seed is best planted on top of the soil – check seed label for planting information!
How do I plant a seed? Continued • Label flat • Date planted • Species and variety • Name • Water • Place in germination conditions • Transplant (if needed)
Define germination • Germination: the development of a seed from a resting stage to a stage of growth.
Define 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.
Explain why some seeds will 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.
Define 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.
Identify the factors affecting 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.
Identify the factors affecting germination Continued • Oxygen Supply • Needed for respiration
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
Light • Affects germination • 4 types of light responsive plants • Full light • Half light/ half dark • Full darkness • No affect either way
Identify 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
Explain the 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
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.
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