HORT 201
Plant Propagation
Laboratory Exercise 2
Deciduous Hardwood Cuttings
Reference: Hartmann and Kester, Chapter 10, pp. 341-350, 363-374.
Key words and terms from CD:
Adventitious roots, auxins, bottom heat, callus, cambium, cuttings, distal, dormancy, hardwood cuttings, intermittent mist, mist systems, parts per million, phloem, preformed roots, proximal, quick dip auxin treatment, root initials, root primordia, stages of root formation, talc auxin treatment, wounding, xylem.
Objectives:
1. To learn how to make deciduous hardwood stem cuttings.
2. To observe the effects of different rooting hormones on rooting of hardwood cuttings.
3. To determine the effects of wounding on rooting of hardwood cuttings.
4. To observe rooting and bud activity under 2 different handling systems.
5. To learn how to callus hardwood cuttings for planting out later.
Introduction: Deciduous hardwood cuttings refer to stem cuttings of wood taken during the dormant period. When possible it is advantageous to use hardwood cuttings because they:
1. are least expensive and easiest to handle
2. do not perish readily
3. are easy to ship
4. require little special equipment to produce
Many deciduous ornamental and fruit species can be propagated by this method. Cuttings from current season's wood are always taken during the dormant season. Best rooting and survival are obtained with cuttings made from stocky but not overly vigorous shoots which grew in full sunlight. Use the center to basal portion of such shoots; avoid the thinner, flimsy, shoot tips. Cutting length is frequently not important to rooting. However, at least 2 buds (the second bud is a safety factor since the first bud will occasionally not develop) should be in a position where you can depend on them to develop into a new shoot. That means that they must be kept away from bottom heat when it is used, and usually out of the moist rooting media where they can rot. Where bud orientation is not obvious, make the distal (terminal) cut 90o and the proximal (basal cut) 45o. Straight cuttings are most common, but heel and mallet cuttings also are used. Tip cuttings are usually only used with conifers.
Examples of different types of hardwood cuttings. Straight cuttings do not include the terminal bud at the end of the stem. Tip cuttings include the terminal bud. A heel cutting is made by pulling stem from a branch so that part of the branch remains attached to the stem.
Wounding the base of hardwood cuttings to expose more cambium cells will stimulate additional root formation. This is usually not done on easy-to-root species but can enhance rooting in difficult-to- root species.
There are many variations in handling deciduous hardwood cuttings (see Hartmann and Kester reference above). Which method is used depends partly on the severity of the winters in a given region. We will study 2 common handling methods in this exercise. Remember that with all methods the key is to encourage rooting while discouraging budbreak. New leaves will quickly wilt and die if there are no roots present to supply them with water. Also, rooted cuttings which have leafed out are more difficult to transplant.
Hartmann, H.T., D.E. Kester, F.T. Davies &R.L. Geneve (2002) Hartmann and Kesters’ Plant Propagation: Principles and Practices, 7th edition. Prentice Hall. (Excellent information on hardwood cutting propagation)
MacDonald, B. (1986) Practical Woody Plant
Propagation for Nursery Growers.
Method I.
Greenhouse. The principle is to use bottom heat to maintain the root zone at approximately 21oC (70oF) to promote rooting, while maintaining the air temperature just above freezing to retard bud development. It's important to start cuttings in winter and transplant them by early spring before air temperatures get too warm. Good ventilation is essential, as the sun will quickly heat the air in a plastic greenhouse even on a cold winter day.
Note: As explained above, minimizing air temperature while providing bottom heat is a very common practice in the propagation of deciduous hardwood species. However, when appropriate growing conditions are unavailable, limited success can be achieved in rooting hardwood cuttings in a (75o F) greenhouse under mist. Under these circumstances bottom heat is not necessary and intermittent mist should be used to reduce desiccation. This approach may be necessary for part of this lab exercise but should still allow us to distinguish relative differences in treatment effects.
Method II.
Refrigerated Room. Bottom heat (70oF) is again used to promote rooting. By locating the box in a refrigerated room, much better control of air temperature is obtained than with the greenhouse. Because reduced air temperature discourages budbreak, there is no urgency to transplant cuttings after rooting occurs and bottom heat is discontinued. Light is not necessary for leaf-less cuttings; darkness, in fact, retards budbreak of some species.
Plants Propagated by this Method:
A. Ornamental trees and
shrubs: Arrowwood viburnum (Viburnum dentatum), multiflora rose
(
B. Greenhouse crops: Roses grown in greenhouses
for cut flower production are usually budded or grafted onto rooted hardwood
cuttings of
C. Fruit crops: Grapes are commonly propagated
by hardwood cuttings in areas where use of rootstocks is not necessary. Hardwood
cuttings of fruit trees are harder to handle successfully than those listed
under A and B above. In the
Procedures for Today’s Lab:
Experiment # 1: Effects of rooting hormones and handling systems
1. Each group should obtain 15-30 stems of one species as directed by the instructor (the number of stems depends on the species). These stems are from the current season’s wood. Please look at example branches at the front of the lab to practice identifying 1 year wood (current season), 2 year wood, etc.
2. Prepare 50 uniform 6-8 inch straight cuttings, each with at least 3 nodes (where buds are). Extra buds are a safety factor since a bud may occasionally not grow.
- stems should have a green inner layer under the bark
- avoid thin, weak shoots
- make a 90o cut at the distal end (i.e., top end), just above a node
- make a 45o cuts at the proximal end (i.e., basal-bottom end), about 1-2 inches below a node
3. Using a knife, wound the cutting by removing two ½ - æ inch long slices of bark from opposite sides at the base of the cutting. Cut deeply enough to expose the green layer under the bark, but not so deeply that the stem is cut in half. Because Forsythia roots so easily, this species does not require wounding.
3. Make 10 bundles of cuttings (each bundle with 5 cuttings).
4. Taking care to keep track of which bundle has been treated with each treatment, treat each bundle as follows with one of the five following treatments listed in the chart below. Be sure that the treatment covers the entire portion of stem that was wounded.
|
Treatment |
# of bundles |
Auxin concentration |
Auxin formulation |
treatment method |
|
a |
2 |
none (control) |
none (control) |
5-second dip in H20 |
|
2 |
8000 ppm K+-IBA1 |
K+-IBA1 8 gm per 1000 mL water |
5-second dip in K+-IBA |
|
|
c |
2 |
1650 ppm IBA2 + 825 ppm NAA3 |
Dip-n-Grow (dilute part Dip-n-Grow with 5 parts water) |
5-second dip in Dip-n-Grow |
|
d |
2 |
3000 ppm IBA2 |
Rhizopon #2 |
talc dip |
|
e |
2 |
8000 ppm IBA |
Hormex 8 |
talc dip |
1indole-3-butyric acid - potassium salt
2indole-3-butyric acid
3α-naphthaleneacetic acid
5. Knock off excess talc from treatments d and e.
6. Each lab group will have two propagation flats. One bundle from treatments a, b, c, d, and e (25 cuttings) will be stuck 2 inch deep in one flat which will be placed in the cooler with 70oF. bottom heat.
7. The second bundle from treatments a, b, c, d, and e (25 cuttings) will be stuck in your group’s second propagation flat which will be placed in Zone 16 with intermittent mist and no bottom heat.
8. Propagation flats are filled with a mixture of course-grade perlite and medium-grade vermiculite (1:1).
Follow these instructions for placing cuttings in the propagation flat:
a. Use a cutting tool or marker to make a 2-inch-deep hole in the media that is a larger diameter than your cutting. This will allow the cuttings to be placed in the media at a depth of 2 inches. Greater depth will cause the bottom of the cutting to be too close to the heating mat; less depth will not provide sufficient warmth.
b. Place the cuttings in the hole. Stick 10 cuttings per row (i.e., two treatments per row). Do not stick the cutting directly into the media because that will remove the treatment residue on the cutting.
c. Fill in the groove to bury the cutting end and using the pressing board to firm the media down between rows after each row is filled in. Each propagation flat can hold 5 -6 rows of 10 cuttings per row. When experiment #1 is completed, 25 cuttings (2½ rows) should be in each flat.
d. Use plastic tags to label each set of 5 cuttings with species, treatment, date, lab section, and a name identifying your lab group.
Experiment #2: Callusing bundles of hardwood cuttings:
1. Make 10 additional hardwood cuttings of the species used in Experiment #1 and place a rubber band around them to hold them together. Dip the base of the bundle in the 8000 ppm IBA (treatment b) solution for 5 sec.
2. Bury the bundle in a box of moist peat moss that is at the front of the lab as described by your laboratory instructor. The box will be stored in the cooler with bottom heat of 70 F.
Experiment # 3 : Other hardwood cuttings:
Both your group’s two propagation flats should now be half full. Repeat experiment #1 with another available species to fill up your propagation flat (10 cuttings per row). Label your cuttings as in experiment #1. When your flat is full take one flat to Zone 16 bench 2, take the other flat to the HORT 201 Cooler 1158 and place it on a heating mat located on the wire shelves on the left-hand side of the cooler.
RESULTS:
Initial scoring for rooting will be done on Lab #5 (Feb. 5). It is unlikely any significant rooting will occur before then. Scoring is done by carefully pulling the cutting to see if it has rooted. Pulling up on your cuttings to check on rooting progress should be done carefully, as this may remove the talc preparation and may break off the new roots. Rooting has started if you feel a slight resistance when you tug very gently on the cuttings.
Final scoring for rooting will be done on Lab #9 (Mar. 18) when the experiment is terminated. Stick your hand or a trowel underneath the cuttings and push the cuttings up to minimize root breakage. Examine and score each cutting for callus and for root formation. Assign a score for root formation using the following scale: (0) no roots or callus; (1) callused but no roots; (2) roots started but only
bumps; (3) few roots; 1-3; (4) some roots; 4-5; (5) many roots per cutting; >5.
Exposed roots will desiccate very quickly, so if you wish to save some of your plants, cover the roots with wet paper towels. Pot up what cuttings you wish to keep after you have collected your data. Label your pot and place it in Zone 21.
Data must be turned in at the end of Lab # 9 (Mar. 18)
Give your lab group’s data recorded on the data sheets of this handout to your lab instructor. Your group’s data sheets will be returned to your group at the next lab. Your group must also decide the appropriate answers to the questions on page 10 and turn those answers in along with your group’s data.
Your instructor will combine the results from the different groups/lab sections and present the combined results at the beginning of lab on Mar. 25. This will provide you with a more complete perspective of the effects of these treatments on rooting.
Candidate species this year:
Shrubs Viburnum rhytidophylloides (Lantanaphyllum Viburnum)
Viburnum dentatum (Arrowwood Viburnum)
Cornus sericea (redosier dogwood)
Cornus ? (yellow twig dogwood?)
Euonymus alatus (winged euonymus, also known as burning bush)
Forsythia x intermedia (border forsythia)
Forsythia x ‘Meadowlark’ (Meadowlark forsythia)
Buxus microphyllum (Little-leaf boxwood)
Hibiscus syriacus (Rose-of-Sharon)
Trees Ginkgo biloba (Ginkgo) – cuttings are from a male
Metasequoia glyptostroboides (Dawn redwood)
Final RESULTS Laboratory Exercise #2 - Deciduous Hardwood Cuttings
Lab section: 1 2 3 Names of group members:____________________________________
Experiment #1 - Effects of rooting hormones and handling systems
______________________________________________________________________________
Species : __________________________________ Date: _________________
Cuttings placed in Greenhouse Zone 16 Mist Bench
______________________________________________________________________________
Treatment (5 cuttings/treatment) # callused only # rooted Average stage of rooting*
Treatment a
control
Treatment b
8,000 ppm K+IBA dip
Treatment c
1650 ppm IBA & 825 ppm NAA
Treatment d
3,000 ppm IBA (Rhizopon #2)
Treatment e
8000 ppm IBA (Hormex 8)
Do not yank cuttings out the media – Instead, scoop out the cuttings
______________________________________________________________________________
______________________________________________________________________________
Treatment (5 cuttings/treatment) # callused only # rooted Average stage of rooting*
Treatment a
control
Treatment b
8,000 ppm K+IBA dip
Treatment c
1650 ppm IBA & 825 ppm NAA
Treatment d
3,000 ppm IBA (Rhizopon #2)
Treatment e
8000 ppm IBA (Hormex 8)
* = Stages of rooting: (0) no roots or callus; (1) callused but no roots; (2) roots started but only
bumps; (3) few roots; 1-3; (4) some roots; 4-5; (5) many roots per cutting; >5
______________________________________________________________________________
Species : __________________________________ Date: _________________
Cuttings placed in Greenhouse Zone 16 Mist Bench
______________________________________________________________________________
Treatment (5 cuttings/treatment) # callused only # rooted Average stage of rooting*
Treatment a
control
Treatment b
8,000 ppm K+IBA dip
Treatment c
1650 ppm IBA & 825 ppm NAA
Treatment d
3,000 ppm IBA (Rhizopon #2)
Treatment e
8000 ppm IBA (Hormex 8)
Do not yank cuttings out the media – Instead, scoop out the cuttings.
______________________________________________________________________________
______________________________________________________________________________
Treatment (5 cuttings/treatment) # callused only # rooted Average stage of rooting*
Treatment a
control
Treatment b
8,000 ppm K+IBA dip
Treatment c
1650 ppm IBA & 825 ppm NAA
Treatment d
3,000 ppm IBA (Rhizopon #2)
Treatment e
8000 ppm IBA (Hormex 8)
* = Stages of rooting: (0) no roots or callus; (1) callused but no roots; (2) roots started but only
bumps; (3) few roots; 1-3; (4) some roots; 4-5; (5) many roots per cutting; >5
Species: __________________________________ Date: _________________
Treatment (10 cuttings) # callused only # rooted Average stage of rooting*
Bundle - 8000 ppm K+IBA quick dip
(treatment b)
* = Stages of rooting: (0) no roots or callus; (1) callused but no roots; (2) roots started but only
bumps; (3) few roots; 1-3; (4) some roots; 4-5; (5) many roots per cutting; >5.
Notes and comments:
CONCLUSIONS:
After final scoring has been completed examine your data above and comment briefly on the following:
1. Did different auxin treatments effect rooting differently?
2. Comment on the difference in rooting ability between the two different species your group used. (which worked best and least)
3. Compare the greenhouse vs. the rooting box in the cooler with respect to:
a) rooting
b) bud break
4. What happened to the bundle of 10 cuttings placed in sphagnum moss?