CONIFEROUS HARDWOOD CUTTINGS. PlSc 300 LAB Learn how to make and handle evergreen hardwood cuttings and observe root initiation.

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1 CONIFEROUS HARDWOOD CUTTINGS PlSc 00 LAB REFERENCE: Text pp. 0 ; 6 7; 8 8. OBJECTIVES:. Learn how to make and handle evergreen hardwood cuttings and observe root initiation.. Evaluate the importance of light intensity on rooting.. Compare Sand vs. Peat:Perlite as medium for rooting.. Compare several species with respect to ease of rooting. INTRODUCTION: Many conifers are propagated by hardwood cuttings taken from dormant, current season s growth. Cultivars of yew (Taxus), American arborvitae (Thuja), falsecypress Chamaecyparis, and shrubby and groundcover type junipers especially are propagated this way. The average cutting consists of a 6 to 8 inch shoot, which has had branches and leaves removed from the proximal (bottom) to inches. Some propagators, especially when stock material is in short supply, use small (shoot) tip cuttings. Because leaves must be present (these are evergreens), measures must be taken to prevent desiccation during root formation. Some commercial operations use mist for protection on warm, sunny days. Most cuttings, however, are rooted during winter in plastic houses tight enough to maintain high relative humidity to prevent foliage desiccation. Air temperatures are maintained cool enough to inhibit shoot growth, while bottom heat is often used to encourage root initiation. Without bottom heat rooting may be slow, resulting in late spring planting and inferior growth the first season. Inclusion of older wood, as in the heel or mallet type of cutting, use of auxin, and basal wounding have been shown to be advantageous in many cases.

2 PROCEDURE: Take a few minutes to study the layout of the outdoor hotbed. Section A contains the deciduous hardwood cuttings stuck last week and will also be used this week. Sections B and C are also for conifer cuttings this week. Sections A and C have Sunshine # medium (abbreviated as P/P). Section B has a rooting medium of sand. All flats have bottom heat (70ºF). Sections A and B are in full sun, but section C will be covered with shade cloth to exclude 0% of available light. Objective above will be achieved by comparing rooting in section C against rooting in section A with Sunshine # medium. Objective will be achieved by comparing rooting in section A against rooting in section B. Each group should do the following (as one group of three or four students). A. Auxin treatment. Prepare the following cuttings. Each group should make 0 total cuttings, ten of each species (five with auxin treatment and five without auxin). Make straight cuttings, 6 to 8 inches long, and remove all foliage from the lower inches. Wound by drawing a knife edge down the lower inch on two sides of the stem. Cut into the cambium of the stem, but avoid splitting. Never allow leafy cuttings to dry. Make eight labeled bundles (use rubber bands if desired), treat bases with auxin (Hormex #8) or plain talc following procedures learned last week. a) Juniperus chinensis - 0 cuttings (treat five with Hormex #8) b) Juniperus sabina - 0 cuttings (treat five with Hormex #8) c) Thuja occidentalis - 0 cuttings (treat five with Hormex #8) d) Taxus x media - 0 cuttings (treat five with Hormex #8)

3 . Stick the cuttings in open space in the flat you used last week (called section A). Use a pencil or your fingers to make an opening in the rooting medium before sticking the cuttings so that the applied auxin or talc stays on the cutting. Cuttings should be stuck into the medium nearly to the lower most foliage and down as close to the heat source as possible. Avoid getting foliage below propagation medium, as this encourages build-up of rot organisms. REMEMBER: always work from left to right and front to back, with your label at the front of your cuttings. Labels should include your names, lab section/group, the name of the species, the bench section (in this experiment - A), and treatment - growth regulator (hormone) or control. B. Prepare the following cuttings using the above procedure. Treat all cuttings with Hormex #8. Wound all cuttings as you did in the previous section. a) Euonymus fortunei Colorata - cuttings b) Buxus spp. - cuttings c) Pyracantha coccinea - cuttings d) Prunus laurocerasus cuttings e) Taxus x media - 0 cuttings f) Thuja occidentalis - 0 cuttings After labeling and treating the cuttings, stick five cuttings of Euonymus, Buxus, Pyracantha, and Prunus in a flat to be placed in section A, B, and C. Stick five cuttings of Taxus and Thuja in section B and C. (You already have five treated cuttings in section A from the previous experiment you just completed.)

4 Your group should check the moisture of the rooting medium twice a week. Allowing the rooting medium to dry out will hinder root initiation and may kill the cuttings. RESULTS: You can tell when rooting begins by feeling resistance when very gently tugging on cuttings. When terminating experiments (about the end of March), stick your hand or a trowel underneath the cuttings and push them up to minimize root breakage. Always keep exposed roots covered with wet paper towels, as they desiccate very rapidly. Rooting is evaluated by scoring each cutting as follows: Score Observed Rooting 0 no roots or callus callus only, no roots one or two roots a few roots ( to ) moderate root mass ( to 0) heavy root mass (> ) Enter the score for each cutting into the following table. Add rooting scores to determine totals for each species in each hotbed section, then divide totals by five to determine average rooting scores for each species in each hotbed section. Enter the means onto the class data sheet as well. Class summary data sheets will be posted for you to record your data at the end of the study. In addition, be sure to tell the rooting percentage for each treatment-environment combination. For instance, if three cuttings rooted in a treatment, the percent rooting success was 60% ( rooted cuttings divided by cuttings made).

5 6 CONCLUSIONS: Examine the class summary data and comment on the following:. Was light important for rooting? How do you think light might benefit rooting?. Which was the better rooting medium? Can we generalize for conifers, or is the best medium species specific?. How might bottom heat promote rooting?. Briefly discuss your personal data. You should be sure to try to explain the potential reasons why your results differed from expected results or from others in the class. C. Devise Your Own Cutting Experiment. You are encouraged to use available facilities to further study rooting of evergreen cuttings.. Have your group select one plant species to use.. Plan an experiment with your chosen plant material.. Consider investigating two factors: a. Auxin concentration effect on number and size of emerging roots. b. Effect of cutting type (straight, heel, or mallet) on rooting. c. Effect of wounding on number, rate, and location of emerging roots. d. Importance of cutting size on root development.

6 7 e. Ease of rooting juvenile vs. adult cuttings. f. Effect of medium on rooting (expand the experiment run under A). g. Importance of foliage in rooting. h. Comparison of rooting of current season s wood vs. - and -year-old wood. i. Foliage tip cuttings. j. Keep evergreen cuttings off of bottom heat for the first four weeks. k. Your own idea.. Be sure to use the appropriate controls for each treatment. See the lab instructor for help.. Make five cuttings for each part of each treatment. All cuttings will be stuck in the hotbed (if room is available) unless directed otherwise. 6. Carefully follow procedures described in the lab when sticking cuttings, and label cuttings carefully. 7. Test the cuttings for rooting as described above (Part B). 8. For your experiments, devise a table that relates the appropriate information: Species, Treatment, Time (since cuttings were treated) Results - control versus treated cuttings - percentage of cuttings forming roots - number of roots per rooted cutting - average length of roots Amount of callus formed (if any) Pattern of callus development Effects of wounding (if completed) Site of wound appearance in relation to callus (if any)

7 8 Rooting Score: Group Data Hotbed Section A A B C Species Cutting No. Control Light, Sand Dark, P/P

8 9 Rooting Score: Group Data Hotbed Section A A B C Species Cutting No. Control Light, Sand Dark, P/P

9 0 Rooting Score: Group Data Hotbed Section A A B C Species Cutting No. Control Light, Sand Dark, P/P

10 Rooting Score: Class Data - Mean Scores Hotbed Section A A B C Species Cutting No. Control Light, Sand Dark, P/P

11 Rooting Score: Class Data - Mean Scores Hotbed Section A A B C Species Cutting No. Control Light, Sand Dark, P/P

12 Rooting Score: Class Data - Mean Scores Hotbed Section A A B C Species Cutting No. Control Light, Sand Dark, P/P c:\plsc00\lab evergreen cuttings-.doc