sexual & asexual reproduction

Sexual & Asexual Reproduction

Vegetative Parts in Asexual Reproduction: Presentation 3 of 3

Asexual Reproduction

• Asexual or vegetative reproduction involves the production of new plants by means of vegetative parts of an existing plant.

• The vegetative parts of many plants have the ability to produce new roots and/or shoots to form a new plant.

• Asexual reproduction is often advantageous over sexual reproduction because:

• new plants reach maturity in less time;

• disease-free plants can be produced in controlled environmental conditions;

• reproduction is possible for plants that do not develop reproductive parts or viable seeds;

• plant selection for desired characteristics is more reliable; and

• new plants are genetically identical to the parent plant.

• Vegetative plant parts used in asexual reproduction include:– Leaves– Stems– Buds– Roots

• Methods of vegetative plant reproduction include:– Cuttings– Layering– Separation– Division– Grafting – Budding – Tissue Culture

Cuttings

• Propagation by cuttings is the most widely used method of vegetative or asexual reproduction.

Cuttings Cont’d

• A cutting is any part severed from the parent plant, including:

• stem cuttings,

• root cuttings, and

• leaf cuttings.

Layering

• Layering involves forcing a vegetative plant part to form roots while still attached to the parent plant.

Types of Layering

• Two types of layering are:– Air Layering, which is the process of forcing roots to

form on a stem, outside the soil– Ground layering, which is the process of

extending a plant part into the ground, covering it with soil, and allowing it to root.

Types of Layering Cont’d

Separation

• Separation involves removing new plants formed on specialized stems and separating them from the parent plant.

Division

• Division is the technique of cutting specialized plant structures into sections and forcing each section to grow into a new plant.

Grafting

• Grafting consists of uniting a hardwood scion from one plant with the rootstock of another similar hardwood plant to form a vascular connection between the two plant parts.

Types of Grafting Techniques

• The following techniques could be used in the grafting method.

Budding

• Budding, which is similar to grafting, consists of removing buds from one plant and placing them on stems of other closely related plants to form a new plant.

Budding Techniques

Tissue Culture

• Tissue culture, or micro-propagation, involves placing a very small piece of plant tissue on a sterilized culture medium.

• Under sterile conditions, the plant tissue multiplies and grows into new plants.

Advantages of Tissue Cultures

• Advantages of tissue culture as a means of asexual reproduction are that:– It allows large numbers of offspring to be produced

quickly– it allows growers to produce disease-free plants; – it is a cost-efficient method of reproducing plants;

and– it allows plants to be produced that have the same

characteristics as the parent plant.

Disadvantages of Tissue Cultures

• Disadvantages of tissue culture include:– The costs of necessary tools and equipment

– The preciseness of establishing and maintaining sterile conditions needed for plant development

– The requirement of additional time and labor as compared to other methods of asexual propagation.

Summary

• Growers use several methods to multiply or increase the numbers of plant species.

• Propagation methods can be sexual (reproducing from seeds) or asexual (vegetative production).