- - AGRICULTURE CORE CURRICULUM - - (CLF6000) Advanced Core Cluster: ORNAMENTAL HORTICULTURE (CLF6250) Unit Title: SEXUAL AND ASEXUAL PROPAGATION ____________________________________________________________________________ (CLF6255) Topic: VEGETATIVE CUTTINGS Time Year(s) 3 / 4 hours 3 / 4 ____________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the student will be able to: Learning Outcome #: (D-8) - Demonstrate in class at least three techniques for making vegetative cuttings (e.g., stem, leaf, root, hardwood, softwood, semi-hardwood). (D-9) - List and briefly describe four environmental factors that affect the rooting of a stem cutting (e.g., soil temperature, humidity, light, and hormonal balance). Special Materials and Equipment: Flats, perlite or other rooting media, pruners or knives, cutting material, rooting hormone and a propagation area References: Bailey, L. H. (1974). THE NURSERY MANUAL. New York: Macmillan. Hartmann, H. T., & Kester, D. (1983). PLANT PROPAGATION: PRINCIPLES AND PRACTICES (4th ed.). Englewood Cliffs, NJ: Prentice-Hall. Ingels, Jack E. (1985). ORNAMENTAL HORTICULTURE: PRINCIPLES AND PRACTICES. Albany, NY: Delmar Publishers. Evaluation: Observation by instructor, quiz TOPIC PRESENTATION: VEGETATIVE PROPAGATION A. Vegetative propagation is asexual (a- is a prefix meaning not or without, asexual means without sex) and uses plant parts such as leaves, roots, and stems to start new plants. Because no new genetic material is introduced (as through pollination), the products of vegetative propagation will be IDENTICAL to the parent plants. B. There are three methods of making cuttings: NOTE TO INSTRUCTOR: You can demonstrate how to make these cuttings as you cover them or as part of a class activity. 1. Plants can be propagated by stem cuttings using a tip (straight) cutting. 2. Some plants can be propagated, with leaf cuttings by using a leaf section, leaf petiole, or by cutting the veins. 3. Some plants can be propagated with root cuttings, by using a cutting of a root and planting it. C. Stem cuttings can be of three different types. 1. Hardwood a. These cuttings are made during late fall, winter, or early spring. b. The plants used are deciduous or conifer. c. Older, established growth should be used. 2. Softwood a. These cuttings are made during spring to summer. b. They are made of the current season's growth (they always have leaves on them). c. They must be kept moist by misting. 3. Semi-hardwood a. These cuttings are made during summer and fall. b. They are made of partly mature growth. c. They must be kept moist by misting. NOTE TO INSTRUCTOR: You may choose to do the activity at this point. D. Several environmental factors affect the rooting of stem cuttings. 1. The rooting media temperature should be maintained at 70-80 degrees Fahrenheit. a. It should be about 10 degrees Fahrenheit warmer than the tops of the cuttings (air temperature). b. This is best done by providing bottom heat, using either a thermostatically controlled electric heating cable or a hot water circulation system under the cuttings. 2. Maintaining high humidity is important. a. For cuttings that include leaves, it is necessary to reduce transpiration. b. This will keep cuttings from drying out before they can root. 3. Light is important for photosynthesis and controlling daylength. a. Leafy cuttings root better under high intensity of light if cuttings receive plenty of water and water temperature is controlled. b. Leafless hardwood cuttings require only a little light for root formation. c. Stem tissue developing in complete darkness is more likely to initiate adventitious roots than tissue exposed to light (etiolation). 4. The rooting medium, especially for difficult-to-root species, can greatly affect the percentage of rooted cuttings. a. It is best if the medium retains moisture, but provides good drainage and aeration. b. A mixture of organic components (e.g., peat moss, sawdust) and inorganic components (e.g., perlite, vermiculite, coarse sand) gives desirable physical properties for rootings. c. Sometimes sand, perlite, or other mineral components are used alone. d. There is no one ideal rooting mix for all cuttings. 1) The particular medium used depends on plant species, cutting type, season, and type of propagation system. 2) Water management of the medium is of prime importance. e. It must be clean and free of decaying organic matter. f. It should be heat pateurized or fumigated to remove pathogenic fungi, bacteria, nematodes, and weed seeds. 5. Young cutting materials root best. a. Cuttings taken from young (juvenile) trees root better than those taken from old (mature) trees. b. Trunk sprouts are good for cutting materials. Tissues of trunk sprouts are in a juvenile stage. 6. Treatments with the hormones called auxins may promote rooting. a. The cuttings are dipped in a solution of auxin in water, or a mixture of dry hormone and talc. b. Then the cuttings are inserted into the rooting medium. __________________________________________________________ ACTIVITY: Since herbaceous plants are easily propagated, you can use coleus, impatiens, or creeping Charlies to produce rooted cuttings in less than one week. 1. Take ten 3-inch coleus cuttings (remove lower 1/2 to 1/3 of leaves). 2. Put a soil mix of 1/3 peat, 1/3 perlite, and 1/3 sand in a gallon can. 3. Using a dibble, or your finger, make a hole and insert the cutting; press soil back around cutting so it does not dry out. Do not bury the leaves. 4. Water the cuttings with about one pint of water. 5. Cover with a plastic bag and place the container where it receives a great deal of indirect light. 6. The coleus or herbaceous cuttings should root in about 3-10 days. 7. If you use softwood cuttings it is recommended that you use a rooting compound (such as Hormodin). They will usually take 2 weeks to a month to root. __________________________________________________________ 1/6/91 MT/clh #%&C