Lab 9

• types of stem cuttings:

  • hardwood
  • semi-hardwood
  • softwood
  • herbaceous
• types of leaf-bud cuttings:

  • single eye
  • double eye
• types of leaf cuttings:

  • leaf blade + petiole
  • leaf blade
• Adventitious buds and roots form at the base of a leaf cutting
• The original leaf does not become part of the new plant
• Leaf cuttings can have new plants regenerate from the petiole or the cut surface of the leaf blade
• Auxin is not generally used for leaf cuttings because it may inhibit shoot regeneration
• Cytokinin is frequently used for leaf cuttings because it may speed or increase shoot production, but it can inhibit root production
• high humidity is crucial for leaf cuttings
• root cuttings are taken during winter and early spring before new growth starts and carbohydrates are high
• root cuttings must regenerate adventitious shoot system and often adventitious roots
• small root cuttings are placed horizontally
• large root cuttings are placed vertically
• root cuttings should be put in soil with the proximal end upward
• adventitious shoots form at the proximal ends of root cuttings
• small, delicate roots should be placed near the surface; keep moist in shaded warm greenhouse
• fleshy roots are planted vertically and should be kept warm and moist
• large roots are planted vertically and are often planted in the field
• factors affecting cutting propagation:

  • time of year
  • tissue maturity
  • exogenous treatments (hormones)
  • wounding
  • environmental factors
• temperature should be carefully controlled throughout the rooting period
• humidity should be as high as possible for cuttings
• adequate drainage should be provided for cuttings
• semi-hardwood cuttings: partially mature wood from recent growth
• semi-hardwood cuttings are taken in late spring to late-summer or early fall
• semi-hardwood cuttings require 1,000-3,000 mg/L auxin
• cuttings: produced by taking a portion of a plant and placing it in contact with a source of moisture and stability
• Stem cuttings are the most popular type of cutting because they are quick to propagate
• Stem cuttings are dependent upon the production of adventitious roots
• Softwood is generally harvested from March to May in Texas
• Softwood cuttings are often easier to root than other types of woody cuttings
• Semi-hardwood cuttings are generally harvested from May to October in Texas
• Semi-hardwood cuttings are made from the current season's growth that has begun to "harden"
• Semi-hardwood cuttings are generally easier to root than hardwood cuttings, but can be more difficult to root than softwood cuttings
• Hardwood are generally harvested between December and February I n Texas
• Some species root poorly from hardwood cuttings
• straight cuttings: often made to maximize a small amount of cutting wood; the base has been totally removed from the stem from which it initially grew
• heel cuttings: made to include a portion of the stem from which they originally grew; allows for the movement of carbohydrates from this tissue back into the hardwood cutting, thus providing more energy for adventitious root growth
• mallet cuttings: made to include an intact portion of the stem from which the cutting initially grew; allows for increased movement of sugars from the older branch
• Herbaceous cuttings can be harvested at any time when the plant has shoots
• Herbaceous growth cuttings are susceptible to water loss