Transcript File
Plant Propagation Essential Standard 4.00: Examine factors relating to plant growth and development. Objective 4.02 • Use sexual and asexual methods of propagation. Propagation • The multiplication of a kind or species. • Reproduction of a species. Sexual Propagation • Propagation from seeds. • Pollen is transferred from the anther to the stigma. • Fertilization occurs and seeds are produced. Germination Rates • Percent of seeds that sprout – 75 out of 100=75% • Rate is affected by seed viability, temperature and moisture. • Rates vary depending on plant and quality of seed. Seeds • Plant depth depends on the size of seeds – larger seeds are planted deeper – water small seeds from bottom by soaking Embryo Seed Coat Endosperm Seeds • Plant seeds no more than 1 ½ times the diameter of the seed – Larger seeds are planted deeper – Smaller seeds are planted shallow (Petunias) • Water small seeds from bottom by soaking to prevent burying them Seedlings (small plants) • The first sets of leaves are called cotyledons – Monocots produce one seed leaf – Dicots produce two seed leaves • True leaves are the second set of leaves • Transplant seedlings when the first true leaves appear • Before planting in the outdoor environment, reduce humidity and water and make the environment more like the outside to “harden off” plants Seeds to Seedlings Advantages of Sexual Reproduction • Fast way to get many plants • Easy to do • Economical Disadvantages of Sexual Reproduction • Some plants, especially hybrids, do not reproduce true to parents • Some plants are difficult to propagate from seeds Plants Started by Seeds • • • • • • • Marigold Impatiens Begonia Coleus Salvia Shasta daisy Pansy Asexual Reproduction • Uses growing plant parts other than seeds • Types of asexual reproduction: – – – – – – cuttings layering division or separation budding grafting tissue culture Rooting from Cuttings • Rooting media should be about 4 inches deep • Best time of day is early mornings because plants have more moisture • Types of cuttings: – stem – leaf – root Stem Cuttings • 1. Start with sterile flats, soil, and tools • 2. Must include a node. A node is a point along a plant stem where leaves or other stems are attached • 3. Internode is the area between two nodes • 4. Cutting is taking a 4-6 inch piece of the plant and forcing roots to grow • 5. Using hormones helps speed up rooting Stem Cuttings • • • • • 6. Dipping the cutting in fungicides helps prevent rotting 7. Herbaceous plants are soft-tissue plants 8. Woody plants are plants that produce woody tissue 9. Rooting media should be about four inches deep 10. Examples of plants that can be started by cuttings – Herbaceous: geranium, impatiens, begonia, coleus – Woody: holly, abelia, rosemary Stem Cuttings-Step 1 Gather all materials needed Stem Cuttings-Step 2 Cut 3 to 4 inch shoot from stem tip Stem Cuttings-Step 3 Remove lower leaves from the shoot Stem Cuttings-Step 4 Dip cut surface in rooting hormone Stem Cuttings-Step 5 Thoroughly moisten rooting medium Stem Cuttings-Step 6 Stick one or more cuttings in rooting media Stem Cuttings-Step 7 Cover with plastic wrap or place on a mist bench in a warm area away from direct sunlight. Stem Cuttings-Step 8 Once rooted, cuttings can be separated carefully and transplanted Leaf cuttings • Usually propagated from herbaceous plants • Midrib vein must be cut in order to make roots form • Examples of plants started by leaf cuttings: – – – – African violet Philodendron Snake plant Jade plant Root Cuttings • Should be spaced three inches apart in rooting area • A sand, vermiculite, or perlite mixture is a good medium for root cuttings • Examples of plants that can be started by root cuttings – Hosta – Daylily Cuttings • The best time of day to take a stem, leaf, or root cutting is early morning because plants have more moisture Layering • Scarring a small area of stem to produce new plants – air layering – trench layering – mound layering Air Layering • 1. Make an incision at the node of a branch • 2. Dust with rooting hormone, place sphagnum moss in plastic and wrap around the incision, forcing roots to grow on the stem of the plant • 3. Once roots form, remove below the new roots for a new plant • Examples: Decora rubber plant, weeping (Benjamin) fig Air Layering Trench Layering • New plants form at each node along the stem while still attached to plant • 1. Cut a trench and lay a branch in the trench • 2. Types of trench layering are simple, tip, serpentine • Examples: grapes, clematis Trench Layering Mound layering • Mounding the soil on a branch • Used for asexual propagation of azalea Trench Layering Division • Cutting apart plant structures for reproduction – – – – – rhizomes tubers runners stolons suckers Division • Used on plants that grow in clumps • Examples: hostas, daylilies, irises • Also used on some grasses Separation • Separating natural structures of a plant without making a cut • Examples: bulbs and corms Grafting • Joining separate plant parts together so that they form a union and grow together to make one plant. Wedge Graft Approach Graft Grafting Terms • Scion-the piece of plant at the top of the graft • Rootstock-the piece of the plant at the root or bottom of the graft • Tools needed: knife, tape, wax • Plants must be related to each other and normally in same genus or family • Examples: maples, fruit trees, sweetgum, pecan Methods of Grafting • If the scion and rootstock are the same size – – – – wedge splice whip and tongue approach Methods of Grafting • If the scion is smaller than the rootstock – – – – cleft side notch bark inlay Budding • A form of grafting when a bud is used instead of scion – patch budding – T-budding – Chip Budding Chip Budding How to perform T-budding Step 2 Step 4 Step 1 Step 3 Budding • Successful budding requires that the scion (top) material have a fully-formed, mature, dormant bud • Rootstock has to be in condition of active growth “bark is slipping” • Refers to vascular cambium actively growing and bark can be easily peeled from rootstock with little damage • Example: rose Tissue Culture (Micropropagation) • • • • A sterile environment is necessary for micropropagation A good way to get the most plants in a short period of time It will give you a plant identical to the parent plant Examples: impatiens, many flowers, vegetable plants Additional Terminology • Corm – enlarged, bulb-like, fleshy structure found at the base of a stem. Usually flattened and round. – Gladiolus, crocus • Rhizome – a creeping underground stem, usually horizontal, that produces roots and leaves at the nodes. – Canna, bearded iris • Stolon – creeping above ground stem that grows horizontally and produces roots and shoots at the nodes – strawberry • Tuber – Swollen, modified stem that grows underground – potato • Sucker – shoot or stem that originates from the roots Advantages of Asexual Production • Plants mature in a shorter time • Budding is faster than grafting • In trench layering, a plant forms at each node on a covered stem • Some plants do not produce viable seed • New plants are the same as the parent plant Disadvantages of Asexual Reproduction • Some require special equipment and skills, such as grafting • Cuttings detach plant parts from water and nutrient source • Some plants are patented making propagation illegal The Uses of Biotechnology in Horticulture What is Biotechnology? • The use of cells or components (parts) of cells to produce products or processes Methods • Tissue culture or micropropagation • Cloning • Genetic Engineering Tissue Culture • Uses terminal shoots or leaf buds in a sterile or aseptic environment on agar gel or other nutrient-growing media to produce thousands of identical plants Cloning • Genetically generating offspring from non-sexual tissue Genetic Engineering • Movement of genetic information in the form of genes from one cell to another cell to modify or change the genetic make-up Benefits of Biotechnology • • • • Produce many identical plants in a short time Increase disease and insect resistance Increase tolerance to heat and cold Increase weed tolerance Benefits of Biotechnology • • • • Increase tolerance to drought Improve environment Increase production Other genetic changes