Plant Propagation Sexual and asexual propagation
Plant Anatomy Flowers, Seeds, and Shoots
Stolon vs. Rhizome Stolon Rhizome
Propagation Sexual Reproduction Asexual Reproduction • Reproduction involving the exchange of genetic information, i.e. seeds and spores. • Reproduction without the exchange of genetic information resulting in an identical clone, i.e. cuttings and division.
Propagating by Seeds • Seed harvesting and storage • When to sow • Seed treatments • Depth • Temperature • Media • Transplanting seedlings • Pathogens
Seeds Collection and Storage Harvesting Storage • When harvesting no longer impairs germination • Maximum dry weight • Dry seeds • Prevent excessive moisture • Cool temps • Rh + Temp < 100
Seeding Direct sow Transplant • Saves time and space • Many cool season crops such as lettuce and spinach • Plants with tap roots such as peas and radishes • Improve germination • Plants that mature slowly • Increase yield or promote flowering
Seed Treatments for Germination • Scarification • Stratification • Soaking
Depth • Light requirements • Twice as deep as the size of the seed • Too shallow is better than too deep
Temperature • Some seeds need certain temperature cycles to break dormancy. • Some crops, such as eggplants, need temps in excess of 80 degrees • As a general rule, temperatures in the mid 60’s are ideal. • Bottom heat can accelerate germination and plant growth.
Media • Seed germination media should be fine, retain moisture, and drain readily. • Fafard Superfine Seed Germination Mix is a good choice. • Avoid media with coarse perlite and large pieces of bark.
Transplanting • Soil temps- plants can take up nutrients when soil temperatures are above 40, but soil temps of 50 for warm season vegetables and perennials is preferred. • Evaluate roots- transplant when roots and reached the side of the container and have started to turn down. Avoid letting transplants become pot bound. • Handle young seedling by their leaves only. It is very easy to crush a stem during transplanting. • Attempt to spread roots out so they are not bent. • Manage shock- maintain consistent moisture. If using fertilizer wait until at least 3 irrigations have occurred before fertilizing.
Pathogens and Pests • Damping off • Insects • Fungus • Animals
Asexual Propagation • Tissue Culture/Micro-propagation • Layering • Grafting/Budding • Division • Cuttings
Layering Simple Layering Air Layering
Grafting Whip and Tongue Budding
Division • Timing- typically right after flowering • Balance- maintain a balance between root and shoot • Manage shock- maintain consistent moisture until established.
Cuttings • Competence: Competent cells found in nodes or basal plate • Timing: Specific to every plant • Condition of stock plant: Disease and pest free. Usually active but not vigorous growth • Cone of Juvenility: Juvenile tissue roots easier. Can be important with hard to root species. Mature tissue fruit or flowers faster, important with grafting fruit trees. • Ripeness: Semi-ripe wood usually roots best • Auxin : Cytokinin • Media- well draining: retains moisture • Temperature- bottom heat will greatly increase rooting speed/ • Humidity- maintain high humidity but not standing water in leaves.
Phytohormones: Auxin • Auxins root ‘em : Cytokinins shoot ‘em • Auxin is synthesized in small amounts in the apical meristem and then transported down the dark side of the plant. • Auxin is photosensitive. • There are numerous forms of synthetic auxin.
Phytohormones: Cytokinin • Cytokinin is synthesized in the roots and promotes cell division. • The relative amount of auxin to cytokinin are key to plants regulating growth.
References • The Complete Book of Plant Propagation, Clark and Toogood, 1992 • Plant Propagation: Principles and Practices, Hartmann and Kester, 1983 • Seed Starter, Heffernan, 1996