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

Place media in container (water gently) 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.