propagation made easy

Propagation Made EasyTake your propagation skills to the next level

30th Annual Florida Master Gardener Continued Training Conference

Dr. Mack ThetfordAssociate Professor of Environmental Horticulture

Mack Thetford: Research Overview

Native plant species establishment for ecosystem restoration

Specific goal: improve the quantity and quality of

Focus areas: reproductive biology of native and invasive plantsapplication of propagation, production and landscape establishment

techniques for coastal restoration on the Gulf coast

Mack Thetford: Teaching Overview

Plant Propagation

Plant Identification

Annual and Perennial Gardening

Landscape and Turfgrass Management

Ecosystems of North Florida

Dendrology

THE MILTON GARDENSDr. Mack Thetford, Director

Friends of the Gardens of Northwest Florida

What We Ask of a Cutting

Regenerate missing parts under conditions of: Loss of water supply Loss of nutrient supply Excessive wounding

Do not rot

C. Cook

Types of cuttings

Stem cuttings Hardwood

Deciduous Narrow-leaved

evergreen Semi-hardwood Softwood Herbaceous

Leaf cuttings• Leaf blade• Leaf blade & petiole

Leaf-bud cuttings• Single node stem

cuttings

Root cuttings

Presenter

Presentation Notes

Cuttings can be classified according to the part of the plant from which they are obtained or the developmental nature of the wood

Adventitious root formation in cuttings

Root growthand development

Root initiation

Dedifferentiation- The capability of previously developed,

differentiated cells to initiate cell divisions and form a new meristematic growing point.

Adventitious root formationPreformed roots (latent root initials)Preformed root initials

and root primordiadevelop naturally on stems while they are still attached to the parent plant.

Presenter

Presentation Notes

Roots may or may not emerge prior to severing the stem piece.

Preformed root initials

Preformed root initials and root primordia develop naturally on stems while they are still attached to the parent plant.

Adventitious roots arising from preformed root initials

Campsis radicans

Adventitious root formationWound-induced rootsWound-induced roots develop only after

the cutting is made, in response to wounding in preparing the cuttings.

These roots are formed de novo (anew)

Wound induced root formation

Day 0

Day 8

Day 12

Types of cuttingsplant part or maturity of wood

Stem cuttings Hardwood

Deciduous Narrow-leaved

evergreen Semi-hardwood Softwood Herbaceous

Leaf cuttings• Leaf blade• Leaf blade & petiole

Leaf-bud cuttings• Single node stem cuttings

Root cuttings

Presenter

Presentation Notes

Cuttings can be classified according to the part of the plant from which they are obtained or the developmental nature of the wood

Stem Cuttings

Hardwood CuttingsDeciduous or Narrow-leaved evergreen species

• Mature wood• Dormant wood• Firm wood • Collected during

dormant season• May also need

older wood for success

Presenter

Presentation Notes

Usually best rooted in a propagation structure with high irradiance, high humidity, and very light misting. Bottom heat of 75 to 80 F have given good results. Removal of lower leaves or branches is common – light wounding -

Hardwood Cuttings

Straight cutting Does not include older wood

Heel cutting Includes only a small piece

of older wood Mallet cutting Includes a short stem section

of older wood

Softwood cuttings Cuttings collected from the soft,

succulent, new spring growth of deciduous or evergreen species.

Presenter

Presentation Notes

The window of availability of this type of cutting is from 2 to 8 weeks for most species. Some species may produce successive growth flushes of softwood. Forsythia, spiraea, Crepe Myrtle While others will not Chionanthus, Elm, and Euonymus Softwood cuttings generally root quicker and easier than other types (two to five weeks) but require more sophisticated equipment. This type of cutting is always made with leaves attached.

Semi-hardwood cuttings(greenwood cuttings)

Woody, broad-leaved evergreen species Partially mature wood from summer to early fall Collected just after a flush of growth

Deciduous plants Leafy summer wood Early fall wood

Presenter

Presentation Notes

Late summer wood which typically has formed a resting bud. Has more carbohydrate storage than a softwood cutting.

Herbaceous cuttings

Succulent, nonwoody stems with leaves retained at the upper end.

Auxins are generally not required but may be used to gain uniformity in rooting and development of heavier root systems.

…to Strip or not to strip?

Presenter

Presentation Notes

Rooted under the same conditions as softwood cuttings. Types of cuttings -apical verses basal, and nodal position of herbaceous cuttings can influence shoot growth and finished plant quality of rooted liners. Succulent species may require callusing for a week or more before inserting into rooting media.

Leaf Cuttings –preformed, primary meristems Rudimentary leaves Stem (with intact bud) Root primordia Foot

New plants develop from a latent primary meristem – from cells that have not fully differentiated.

Leaf blade & margin

Leaf Cuttings –Wound-induced, secondary meristems

African violet Begonia Snake plant

Adventitious rootformation

Preformed roots

(latent root initials)

Presenter

Presentation Notes

Roots may or may not emerge prior to severing the stem piece.

Adventitious root formationWound-induced rootsWound-induced roots develop only after

the cutting is made, in response to wounding in preparing the cuttings.

Begonia sp.

4 STAGES OF ADVENTITIOUS ROOT FORMATION

ROOT INITIATION1. Dedifferentiation of specific

differentiated cells2. Formation of root initials3. Development of root primordiaROOT GROWTH4. Growth and emergence of root primordia

Root growthand development

Root initiation

Wounding of stem cuttings to enhance rooting

Light Heavy

Presenter

Presentation Notes

Stripping of leaves - may benefit some species (Berberis, Juniperus) but not benefit others (Spiraea, Forsythia and Weigela). Reduce bench space requirements Increase contact area between cutting and media Can improve absorption of auxin (auxin is predominantly absorbed via the cut surface not through the epidermis or periderm. Light wounding – knife Heavy wounding – paring knife (carrot peeler) – (magnolia, Rhododendron) The cuttings should be treated with auxins after wounding for the greatest benefit May permit greater absorption of applied growth regulators May remove a physical barrier to new emerging roots (sclerenchyma)

AuxinsAuxin is required for initiation of adventitious

roots on stems, and it has been shown that divisions of the first root initial cells are dependent upon either applied or endogenous auxin.

Auxins – natural and syntheticIndole-3-acetic acid (natural) Considerable auxin activity but easily

metabolized by the plant

Indole-3-butyric acid (natural) More effective than IAA for rooting and not

easily metabolized by the plant.

α-naphthalene acetic acid (synthetic) More effective than IAA for rooting

Rooting Chemicals, formulations and carriers

IBA is the best auxin for general use nontoxic to plants over a wide concentration

range effective in promoting rooting of a large

number of plant species a relatively stable compound as a powder or

liquid IBA may be toxic to softwood cuttings of some

species

What are Rooting Cofactors?

Rooting cofactors

(Diphenols)(IAA Oxidase /Peroxidase)

(Borate)

Auxin

Induction of wound root initiation

Naturally occurring substances that appear to act synergistically with Auxin in promoting rooting.

Classification of Plant Rooting Response to auxin

Easy to Root –plants that have all the essential endogenous substances plus auxin. When cuttings are made and placed under proper

environmental conditions, rapid root formation occurs.

Auxin may enhance rooting, but is generally not required.


Moderately Easy to Root -plants in which the essential endogenous substances are present, but auxin in limiting.

Auxin is needed to enhance rooting.


Recalcitrant (difficult to root) –plants in which an essential endogenous substance is limiting or the plant lacks the cell sensitivity to respond to these substances, even though natural auxin may or may not be present in abundance.

Auxin application provides little or no enhancement of rooting.

What can be done to improve rooting?

Presenter

Presentation Notes

Auxin application provides little or no enhancement of rooting.

Environmental ManipulationWater Relations – Humidity Control

1. Maintain an atmosphere with low evaporative demand.

2. Maintain acceptable temperatures for the regeneration process at the cutting base and avoid heat stress of leaves.

3. Maintain light levels suitable for photosynthesis and carbohydrate production.

Presenter

Presentation Notes

Water status of cuttings is a balance between transpirational losses and uptake of water. Water uptake through the leaves is not a major contributor to this water balance in most species. The cutting base and any foliage immersed in the media are main entry points of water. Maintain an atmosphere with low evaporative demand, minimize transpirational water losses from cuttings. Cuttings without roots cannot effectively replace transpired water loss Photosynthesis and carbohydrate production are necessary to to maintain the cuttings (respiration) and for growth once root initiation has occurred.

Water Relations – Humidity Control (vapor pressure)

Vair > Vleaf

no water loss from leaves

Vair < Vleaf

water loss from leaves

Vleaf

Vair

Presenter

Presentation Notes

Water uptake in cuttings declines after initial insertion into media. This is caused by blockage of xylem vessels and/or collapse of tracheids, - similar to problems associated with cut flowers. (Wounding will sometimes increase the contact area thereby improving water uptake) The driving force that determines the rate at which cuttings lose water is the difference in pressure between water vapor in the leaves and that in the surrounding air. Commercial propagation systems are designed to minimize this difference either by decreasing Leaf Vapor pressure by reducing leaf temperatures (mist systems) or decreasing the Air vapor pressure by preventing the escape of water vapor (enclosed polytent).

Mist Control systems Static – rely on clocks and timers to

manage intermittent mist and fog systems.

Dynamic – rely on environmental parameters to determine water status of cuttings.

Mist Controls - Static

24 voltTransf ormer

24 HourClock

Shortint ervalClock

120 VoltPowerSource

PressureRegulat or

SolenoidValve

In-lineScreen

Wat erValve

24 hour clock andshort int erval clock

Presenter

Presentation Notes

Static – 24 hour clock to control time of operation Interval timer to control interval of misting Do not respond to daily fluctuation in light irradiance, cloud cover, relative humidity or temperature. Static – rely on clocks and timers to manage intermittent mist and fog systems.

Basic mist systemplumbing kit $55.00

P40-075 –DIG 24 3/4 inch VAC Preset Drip Zone Valve Assembly

$33.00

R750 –DIG Adjustable Stake Sprayer Kit

$20.00

Static Controller ($200) Intermatic 24 Hour Outdoor Timer HB31R

$30.00 Up to 2 ON / 2 OFF settings per day with a manual override

ON/OFF switch

Intermatic Repeat Cylcle Timer Model C8815 10 min Dial Cycle $140.00

5 second tripper actuating time. Short Range Cycle Timers provide repeat cycling for “ON”

times. Ten combination “ON/OFF” trippers supplied with each switch.

Honeywell 24V Step-Down Transformer $20.00

120v/24v step down transformer, knockout mount, boxed.

Mist Controls - Static120 VoltPowerSource

PressureRegulat or

SolenoidValve

In-lineScreen

Wat erValve

Solid Stat e Timer

SolidStateTimer

Presenter

Presentation Notes


($30) Up to 2 ON / 2 OFF settings per day with a

manual override ON/OFF switch Sentinel DRT-1 Repeat Cycle Timer with

Photosensor ($110) designed to control devices that must be activated on a

repeating cycle can be set in hours, minutes and seconds.

Honeywell 24V Step-Down Transformer ($20)

120v/24v step down transformer, knockout mount, boxed.



ON/OFF switch

Phytotronics 1A Single Zone Controller Model No: 1A Catalog No: 1080 ($300)

The controller is provided with a 24 volt AC wall-mount transformer

The "seconds of on time" knob allows for 2, 4, 6, 8, 10, 12, 15,20, 30, 40, 50, and 60 seconds of mist.

The "minutes between on time" knob allows for 2, 4, 6, 11, 15, 20, 30, 60, and 120 minutes between mist cycles.

Dynamic Control systems Electric leaf Carbon electrodes (evaporation)

Screen Balance (Mist-A-Matic) Mercury switch (evaporation) weight of

water on a screen. Photoelectric cell Conducts current in proportion to

irradiance.

Presenter

Presentation Notes

Computerized controllers can be programmed to monitor air, media, leaf cutting temperature, light irradiance, and vapor pressure differences between air and leaf and the information used to establish the frequency and duration of mist or fog.

Mist Controls - Dynamic

ScreenBalance

120 VoltPowerSource

24 VoltTransformer

PressureRegulator

SolenoidValve

In-lineScreen

WaterValve

Mist-A-Matic

Propagation Bench

Presenter

Presentation Notes

Dynamic – rely on environmental parameters to determine water status of cuttings. Dynamic control systems – may be more precise in regulating water management than static control systems. Electronic and mechanical leaves, light sensors, and humidistats.

Dynamic Controller ($230) Intermatic 24 Hour Outdoor Timer HB31R


ON/OFF switch

Electronic Leaf Mist Control $200 Includes 24 VAC transformer and 20' of 18-gauge two-strand

bell wire for easy attachment to a 24V solenoid.

Enclosure Systems Low polyethylene

tunnels Cold or hot frames Contact polyethylene

systems Indoor polytents

Presenter

Presentation Notes

these systems have an advantage of avoiding the nutrient leaching problems of mist propagation

Simple Enclosure Systems

Alternative systems

Subirrigation Water is supplied by capillary action through a

coarse medium. Can be used in combination with an enclosure

system.

propagation made easy

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