Layering

• layering: a type of vegetative propagation in which adventitious roots are initiated on a stem while still attached to the parent plant
• uses of layering:

  • natural layers
  • highly successful for species that are difficult to root by cutting propagation
  • produce a large plant quickly
  • allows propagation with limited resources
• increased regeneration capacity with layering method due to:

  • physical attachment of the stem to the mother plant (continuous supply of water/minerals)
  • increased accumulation of photosynthates and hormones in the rooting area
  • excluding light to the stem in the rooting zone
  • invigoration and rejuvenation of stock zone
  • utilizing seasonal effects on rooting
• Layering is expensive due to large space requirement, greater labor requirements, and special materials
• Layering is not necessary for easy-to-root species
• prior to layering:

  • select true-to-type stock plants
  • disease/pest free
  • appropriate age/size
  • proper nutrition before layering
• during layering:

  • protection from temperature extremes
  • proper hydration
  • provision of conditions to facilitate rooting
• treatments that enhance rooting:

  • auxin
  • wounding
  • light exclusion
  • substrate provision
• types of layering:

  • simple
  • compound
  • serpentine
  • air
  • mound/stool bed
  • trench
• simple layering: bending of a shoot to the ground to induce formation of adventitious roots
• Simple layering works best in the spring with 1-year old wood
• Simple layering is harvested in fall or next spring
• compound layering: an entire side shoot is covered with rooting substrate; shoots develop from each node
• Compound layering is used for shrubs and woody and herbaceous vines
• serpentine layering: modification of compound layering; more than one portion of the stem is alternatively covered and exposed
• air layering: a girdling cut is made in the stem, exposed surface is scraped, moist substrate is placed around cut stem, area is sealed
• Air layering is done in spring or summer on current or year-old shoots
• Girdled stems can be covered with aluminum foil for heat control
• Mound/Stool bed layering is the most important commercial form of layering
• Mound/stool bed layering is best for plants that branch from the base
• Mound/stool bed layering is done during the dormant season, before new growth starts in the spring
• drop layering: a modification of mound layering where plants are grown in double-stacked containers, rather than in the field
• trench layering steps:

  1. mother plants planted in the row at an angle
  2. plants are laid flat
  3. soil or sawdust is added for etiolation
  4. at the end of the season, the medium is removed and the rooted layers are cut close to the parent plant
• Tip layering is used for berries
• runner: a specialized stem that develops from the axil of a leaf at the crown of a plant, grows horizontally along the ground, and forms a new plant at one of the nodes
• stolon: specialized underground/along the ground stems that grow laterally from the crown of the mother plant to produce either another plant or tuber
• natural layers:

  • offsets
  • bulbs
  • corms
  • bromeliads
• Suckers arise as adventitious shoots from roots
• crown division: separation of individual stems or branches making up the crown or shoot portion of the plant and transplanting as rooted layers
• Crown division is usually done in the spring just before active growth begins or in the fall if active growth is produced after flowering
• factors affecting layering:

  • nutrition
  • minerals
  • carbohydrates
  • stem treatments
  • bending
  • girdling
  • hormones
• environmental effects:

  • light exclusion
  • blanching
  • etiolation
  • banding
  • moisture, temperature, oxygen
  • stock plant development
  • timing
  • pruning
• A specialized stem that emerges from the axil of a leaf, grows horizontally along the ground and produces new plantlets at every other node is known as ___

  runner
• ___ is also known as Circumposition or Gootee

  air layering
• Generally layering is started at what time during the year?

  late winter/early spring
• Air layering is carried out by enclosing the shoot with ___

  moistened sphagnum moss
• Layering differs from cuttings in that ___

  layering initiates roots before shoot is removed
• List two physiological reasons why layering can increase probability of rooting

  • There is an increase in carbohydrates around the layered area
  • Auxin is sometimes applied to the layered area
• ___ method is a modification of compound layering

  serpentine layering
• Removal of a layer of bark around the stem in air layering is known as ___

  girdling