Plant Propagation

• One of the most rewarding and satisfying activities in horticulture is plant propagation.

• Plant propagation is the heart of all work in the field.

What is plant propagation?

• Making new plants from old plants

• There are two (2) types of propagation:

sexual

asexual (vegetative)

Why propagate plants

• To multiply numbers

• To save wanted traits

• To improve a species of plants

• Biotechnology helps improve food production, quality of flowers, and resistance to disease in plants.

• Gene manipulation may someday cure many of our most deadly diseases.

Sexual Propagation

• Involves the union of pollen with an egg in the ovary.

• These male and female cells may be from the same plant (self-pollination) or from

• Separate parent plants (cross-pollination)

• Seeds are a way of rapidly increasing the number of a certain plant.

• Many plants reproduced from seed will differ from the original plants.

• This is because genes from each of the parent plants are represented in the new plant. Thus, a variety is created.

Principles of Genetics

• Gregor Mendel, an Austrian Monk, is recognized for discovering the basic principles of genetics.

• Genetics is the study of how characteristics are passed from parents to offspring.

• He used observations of pea plants to develop these principles:

• In all organisms, there is a pair of genes in every cell that determines every trait in that individual organism.

• Individuals receive one gene for each trait from each parent.

• Genes are transmitted from parent to offspring as unchanging units.

• In the making of reproductive cells, gene pairs separate; with only one gene for each trait is contained in each gamete.

(sex cells: pollen or eggs)

Each gene passed on by the parent plant is called an allele

• A visible characteristic is called a phenotype

• The combination genes from parent plants is the genotype

• When different genes are present for a single trait, in most cases only one trait will be expressed (seen) in the offspring.

• The seen trait is called a dominant trait

The masked or unseen trait is a recessive trait

• A dominant allele is written as an upper case letter symbol (T)

• A recessive allele is written as a lowercase letter symbol (t)

• In plants, the color red is a dominant trait, white flowers are a recessive trait.

• If a plant has two (2) dominant genes for a trait, it is called pure dominant. (TT)

• Dominant homozygous

• A plant with two(2) recessive genes is pure recessive (tt)

• recessive homozygous

• A plant with two (2) different genes for a trait (Tt)

• It is heterozygous.

• Even though the individual has the recessive gene, the recessive trait is not seen. Only the dominant feature shows up

Expected & Observed Results

• Question:

How can knowing the types of genes that each parent has be helpful?

• Traits the offspring will have can be predicted

• The color, size and shape of the petals can be pre-determined by understanding what traits will appear when two plants are cross-pollinated.

• Biotechnology allows us to build or re-build plants to produce better quality flowers, fruit or growth habit by combining the best traits of different plants.

Hybrid Seed

• Hybrid seed are specially produced seed that germinate into plants which appear to be genetically identical.

• If seed are taken from these hybrid plants, the resulting plants will have a variety of combinations of traits. If only the original traits are desired, do not use seed from hybrid plants.

• Chose seed from named varieties only.

Sowing Seed

• Seed propagation of is used for many herbaceous annuals, and perennials.

• The proper environmental and cultural conditions must be provided:

1) temperature

2) moisture

3) light

4) media

1)Place media in container (water gently)

2)Slowly shake seed onto media

a. broadcast: randomly & evenly shake out over the media

b. row plant: place seed in even rows*

(*best method to avoid spread of fungus /diseases)

3) cover seed with a thin layer of media

4) water gently

5) place in area with higher humidity, and increase soil temperature to specified level for the seed growing. (bottom heat range 65’ – 70’)

6) label container with Named variety. date sown

Asexual Propagation

• Reproduction without sex.

• Occurs naturally with most plants,

• Has become very important in the Horticultural Industry.

• Clones – plants genetically identical being produced asexually (uses part of a plant)

• Pluses to clones:

The new plant is genetically identical

The new plant is quicker to get to mature size.

Disadvantages of Using Seed to Propagate New Plants

• Seedlings may take too long to mature• Seed from some plants may be slow to

germinate (Adds to Costs)• Varying genetics transfer to off spring with

each generation.

• Seed production is mainly used when growing bedding plants, (annuals,perennials, and vegetables)

• Asexual Propagation Provides:

• 1. uniformity of large numbers of plants

• 2. to sustain wanted or desired traits (characteristics)

• 3. rejuvenate sick or scraggly plants

Methods of Propagating Plants Asexually

• Stem Cuttings• Cane Cuttings• Leaf Cuttings• Leaf-bud Cuttings• Layering• Air Layering• Division and Separation• Tissue Culture• Grafting

Grafting

• The method of grafting is connecting two plants or plant parts together so they unite and continue to grow as one plant.

• Grafting is possible only when the two plants are related at least at the family level.

• A graft consists of two parts:

• Scion: • A short piece of stem with 2 or more buds,

becomes the top of the new plant

• Understock: (rootstock)

• The lower part of the graft. Becomes the root system of the new plant

•

Reason(s) for grafting

• Propagate plants difficult to propagate by other means

• Used most often in orchards, shade trees, and roses

• Creates dwarf plants• Creates plants with more hardy

characteristics

Types of Grafts

• Whip and tongue graft-

• Used of wood smaller than an inch• Allows vascular tissue to match up

Types of Grafts

• Cleft graft- • Used when the understock is larger than

the scion.• Vascular tissue must match up so scions

are inserted at the edges of the understock

Types of Grafting

• Slip Graft (Side Graft)-

• Quickest graft, although hard to keep together (lined up)

Types of Grafts

• Saddle graft – scion is cut so it sits over the understock a very tight fit is achieved

Budding/Bud Grafting

• Similar to Grafting except the scion is a single bud with a small section of bark.

• Practiced in early spring just before plants break dormancy.

Types of Budding

• T- Budding -

• buds removed from a plant with desirable traits then attached to an understock to form new plant

• The rootstock is cut in a “T” shape, the bud is slipped into the cut and tied off with a band. It is then covered with beeswax

Types of Budding

• Patch Budding- desired bud is cut out like a stamp patch. The same shape patch is cut out of the understock.

• The bud is placed into the patch on the understock then tied off and covered with beeswax

• For both types of budding, the top of the rootstock is cut just above the new bud once it opens to become the new plant's top

• Grafting is important to the horticulture industry because it has enabled growers to create new plants while using the best traits of others.

• The wine industry of Europe was saved by the inferior rootstock of the 'Concord' Grape.