Final Exam- Plant Propagation

What is IPPS?

International Plant Propagator’s Society

Cutting Propagation Definition

A plant propagation technique that utilizes a portion of the stem, root, or leaf that is cut from the parent plant and induced to form roots and shoots by chemical, mechanical, and/or environmental manipulation. The new independent plant produced is a clone of the parent plant.

What are the three types of cuttings?

• Root

• Stem

• Leaf and leaf bud

What are the three types of woody stem cuttings?

• Softwood (Spring to early summer)

• Semi- hardwood (Summer to fall)

• Hardwood (Late fall to winter)

*Herbaceous is a type of non-woody stem cutting

What are the three types of hardwood stem cuttings?

• Straight

• Mallet

• Heel

Three types of leaf cuttings?

• Leaf with petiole

• Entire leaf blade

• Portion of leaf blade

Leaf Cutting Definition

Utilizes leaf blade or leaf blade plus petiole to regenerate a new plant

What organs are formed from leaf blade cutting?

shoot and root

Liners

Starter plants that comes from cutting

Seedlings

Starter plants that come from seeds

Factors affecting rooting of cuttings

• Genetics

• Timing

• Wounding

• Hormones

• Nutrition

Cutting Positions

• Topophysis: Different growth characteristics when different parts of the plants are used as cuttings

• Orthotropic: Cuttings growing vertically

• Plagiotropic: Cuttings growing laterally

Factors affecting rooting of cuttings

• Banding

• Etiolation

• Shading

• Combined

Three factors of hormones that influence rooting of cuttings

• The type

• The concentration

• The application method

What are hormones?

Chemical messengers that regulate plant growth.

The Big 5 Hormone

• Auxin: stimulates root initiation and elongation

• Gibberellin: promotes shoot elongation(cell enlargement)

• Cytokinin: encourage shoot and bud formation (cell division)

• Ethylene: Enhances rooting by promoting auxin sensitivity and cell differentiation (maturation)

• Abscisic (ABA): Helps reduce stress and water loss (stress regulator)

Methods of Applying Auxins

• Liquid

• Powder

• Double Dip (liquid + Powder)

• Foliar spray

• Gel

1 PPM

1 mg pure substance per liter of water

The four functions of rooting medium

• Hold the cutting in place

• Provide moisture for the cutting

• Permit air exchange to base of cutting

• Create dark or opaque environment by reducing light penetration to the base

Three major rooting media substrates or compounds

• Peat moss

• Perlite

• Pine Bark

Advantages of Mist

• Evaporation cools leaf

• Allows full sunlight to reach leaf

• Washes off fungi from leaves

Preventative Disease Control

• Disease-free stock plants

• Chemical treatment of cuttings

• Beneficial microbes

• High water quality

Three factors of light

• Quality

• Quantity

• Photoperiod

What is an important management practice?

Record keeping: important to be as detailed as possible

Care of cuttings during rooting

• Cutting Nutrition

• Environmental Conditions

• Sanitation and IPM

• Weed Control

• Herbicide Use in Propagation

Hardening off

Adapting the cuttings to outdoor environmental conditions

4 propagation house tips

1. Know our water pressure and water quality

2. Use a reliable timing system

3. Space misters and plants correctly

4. Create ideal temperature

Layering Propagation Definition

A system of vegetative propagation where stems are rooted while still attached to the source plant.

Simple Layering

Stem is bent to the ground, held in place an covered with soil. Only a single portion of the stem between base and shoot is covered with soil.

Compound Layering

A branch with numerous nodes is laid horizontally and covered with soil. Shoots develop from each node.

Serpentine Layering

Similar to compound layering except that each alternating node is covered with soil, leaving one node to root and the other node to develop a new shoot.

Air Layering

An aerial stem is girdled and enclosed with rooting media (usually peat moss) to produce rooted layers in the upper part of the plant.

Mound Layering

Shoots are cut back to the ground and soil or rooting substrate is mounded around them to stimulate roots to develop at their bases.

Drop Layering

A modification of mound layering where the plants are growing in double -stacked containers rather than in the field

Trench Layering

The initial stem used to establish the layering system is laid horizontally in a trench. Shoots develop from nodes along the stems that are then covered with mounded rooting substrates and roots also form at nodes.

Hilling up

The mounding of soil or rooting media around the base during layering

Pegging Down

The practice of holding the stem horizontally in place with any type of wire metal, or wooden fastener.

Natural Layering

Layering methods that occur naturally in nature by some plants

What is the most important means for clonal regeneration of many horticultural crops?

Cutting Propagation

How much is labor costs of propagations?

Up to 80%

Stem and leaf bud cuttings only need to produce what?

Adventitious roots

Root and leaf cuttings need to develop what?

Both adventitious roots and adventitious buds

Dedifferentiation

The ability of previously developed, differentiated cells to initiate cell divisions & form new meristems = adventitious roots and buds

Adventitious roots

Roots that arise on aerial plant parts , underground stems

Adventitious buds and shoots

Those that arise from any part other than terminal, lateral or latent buds and stems

Preformed (latent) root initials

develop naturally on the stem and lie dormant or active growth

Where are hormones produced?

In meristems (actively growing regions)

Grafting

the art of joining two pieces of living plant tissue together in such a manner that they will unite and subsequently grow and develop as one composite plant.

Reasons to do grafting in the first place

A way to clone material that is difficult to root
-Improve branching architecture of trees
-Improve tolerance to biotic and abiotic conditions (rootstocks)
-Preserve germplasm
-Dwarfing (makes plant smaller bc limited by rootstock)
-Uniformity

Rootstock

the root portion of a grafted tree

Scion

Grafted piece of plant that is attached to the root stock; the top portion of a grafted tree

Interstock

In between the root stock and the scion, usually to resolve compatibility issues

5 important element for successful grafting

1. The rootstock and scion must be COMPATIBLE.
2. The VASCULAR CAMBIUM of the scion must be placed in direct contact with that of the root stock.
3. Must be done at a time where the rootstock and scion are in the PROPER PHYSIOLOGICAL STAGE.
4. All cut surfaces must be PROTECTED FROM DESICCATION (drying out).
5. PROPER CARE must be given to the grafts for a period of time after grafting

Vascular cambium

A cylinder of meristematic tissue in woody plants that adds layers of second vascular tissue called secondary xylem (wood) and secondary phloem.

Three categories or types of grafts

-Detached scion graftage (most common)

-Approach graftage (brining complete plant parts together than pruning after graft has healed)

-Repair graftage (used to heal or patch wounds in tree cambia)

Four types of detached scion graftage

• Apical graftage

• Side graftage

• Bark graftage

• Root graftage

Types of Apical Graftage

-Whip-and-tongue Graft
-Splice Graft (whip graft)
-Cleft Graft (split graft)
- Wedge Graft (Saw-Kerf Graft)
-Saddle Graft
-Four-Flap Graft (Banana Graft)
-Hole Insertion Graft

When is grafting usually done?

Most grafting is done in late winter or early spring before new growth begins, but it can be done in summer as well depending on the type of grafting.

Desiccationn

drying out

A shoot can. be attached to the epicotyl root portion and create a new plant.

Epicotyl Grafting of Camellia oleifera (tea oil)

Budding

The art of joining only one bud of a living plant with another living plant in such a manner that they will unite and subsequently grow and develop as one composite plant.

• a form of grafting in which the scion consists of a single bud and a small section of bark with or without the wood.

What are the 2 most important types of budding for woody ornamentals and fruit trees?

Chip budding and T-budding

Advantages of Budding

• Numerous clones from a single piece of stem

• Bulky scions is eliminated

Formation of the graft Union

1. lining up vascular cambiums of the Rootstock and scion

2. Wounding Response

3. Callus Bridge Formation

4. Wound-Repair Xylem and Phloem: Differentiation of vascular cambium across the callus bridge

5. Production of secondary xylem and phloem from the new vascular cambium in the callus bridge

Factors influencing Graft union success

• incompatibility

• Plant species and type of graft

• Environmental conditions during and following grafting

• polarity

Types of specialized organs

Bulb, corm, tuber, tuberous stem, tuberous root, rhizome, pseudobulb

Propagule

Any plant organ that is used for the purpose of propagating the same plant to the next stage in its life cycle

Geophyte

Type of plants that can survive part of their annual life cycle as a dormant, fleshy, underground structure.

Bulb

a specialized underground organ consisting of short, fleshy, stem axis (basal plate), bearing at its apex a growing point or a flower primordium enclosed by thick, fleshy scales

3 Parts of a bulb

-Stem Axis (basal plate)
-Flower Axis / apical growing point
-Thick, fleshy scales

Bulb scale

Expanded fleshy leaf base of a bulb; contains food

Basal Plate

short, thickened stem of a bulb; where new organs form

Bulblets

miniature bulbs that form in the axil of a bulb scale; develop from the basal plate

Offsets

Bulblets grown to full size

Two types. of bulbs

• Tunicate (laminate) bulbs

• Nontunicate bulbs (scaly bulbs)

Corm

a unique geophytic structure which is the base of the stem axis is swollen, has nodes and internodes, and is enclosed in a dry membranous tunic

Ex. Gladiolus

Cormels

miniature corms

Tuber

special kind of swollen, modified stem structure that functions as an underground storage organ

Tuberous root

large swollen secondary root; different than true tuber

Ex: sweet potato

Tuberous stem

swollen stem; different than true tuber

Rhizome

specialized stem structure in which the main axis of the plant grows horizontally at, or jut below the surface

Ex: Ginger, bamboo, grass

Pseudobulb

False bulb, produced by many orchid species, consists of enlarged fleshy section of stem

Benefits of Asexual Propagation

-Uniformity
-Propagate non-seed producing plants
-Avoid soil borne diseases
-Create pest resistant plants
-Incorporate environmental tolerances
-reproduce and retain genetic traits of a hybrid
-control size and form of a plant
-can be faster and easier, cheaper

Seed Definition

A matured ovule containing an embryo that is usually the result of sexual fertilization

Three Parts of Seeds

• Embryo

• Storage Tissue

• Protective outer covering

Embryo

Shoot and root meristem, embryonic leaves

Storage Tissue

(variable amounts and types): endosperm, cotyledons, etc.

Protective Outer Covering

Seed coat or fruit covering

What are the steps before seed development?

pollination and Fertilization

Pollination

Transfer of pollen from anther to stigma

Fertilization

the fusion of haploid (1n) male and female gametes inside the ovule.

Funiculus

Tissue that attaches the developing seed with the mother tissue (fruit)

Flower Parts —> Fruit/ Seed Part

• Ovary

• Ovule

• Embryo sac

• 2 polar nuclei + 1 sperm

• Egg cell + 1 sperm

• Integuments

• Fruit tissue

• Mature seed

• Inner part of seed

• Endosperm

• Embryo

• Seed Coat

Three stages of seed development

• Histodifferentiation

• Cell expansion

• Maturation drying

Histodifferentiation

Embryo differentiation; cells undergo specialization in the embryo and endosperm; rapid cell divison occurs

Cell Expansion

Cells increase in size due to water uptake (mainly). storage reserves material, and synthesis of cell structures

Maturation Drying

seed loses excess moisture and undergoes physiological changes to enhance desiccation tolerance

Epicotyl

The upper portion of the axis of an embryo or seedling above the cotyledons

Hypocotyl

The portion of an embryo or seedling situated between the cotyledons and radicle

Seed Coat

Outer layer of the seed developed from the integuments of the ovule