MEANING OF PROPAGATION
Propagation simply means reproduction. It is necessary for crops to propagate so that they can increase in numbers and also maintain their useful characteristics.
METHODS OF PROPAGATION
There are two types of propagation; these are sexual and Asexual/Vegetative propagation.
Sexual Propagation involves planting crops by means of seeds. Seeds can be planted directly in the field or first in the nursery before being transplanted. Examples of seeds which are planted first in the nursery are oil palm, cocoa, coconut etc. common crops that that propagated sexually are cowpea (beans), maize, pawpaw, rice, groundnut etc.
A seed when planted undergoes the following processes.
- Germination: the process whereby the embryo of a seed resumes growth under favourable conditions.
- Emergence: this refers to the appearance of a seedling above soil level.
Conditions necessary for germination of seeds are
- Adequate moisture
- Viable seed (living embryo)
- Optimum temperature
- Adequate air
ADVANTAGES OF SEXUAL PROPAGATION
- Seeds are cheap to obtain.
- The seeds are portable.
- They are convenient to handle.
- They are easy to store.
- They are easy and cheap to transport.
- Seeds can be stored for longer periods.
- Crop population increase can easily be obtained through the use of seeds.
DISADVANTAGES OF SEXUAL PROPAGATION
- Some seeds produce plants that do not resemble their parent plants
- Some seeds produce low yields during the first year
- Plants grown from seeds are usually not uniform in growth, maturity and yield
- Plants grown from seeds take a long time to mature and produce fruits
Asexual propagation is the production of new plants from the parent plants using vegetative parts. The vegetative parts include the stem, leaves and roots. Asexual propagation is also being called vegetative propagation. Plants that need to be propagated asexually possess the following characteristics:
- They do not produce seed e.g pineapple
- They produce seeds but are not viable for planting e.g Banana
- They take many years to mature and are easier to propagate via vegetative means e.g cocoa.
Asexual propagation can be divided into five, namely:
DIVISION: Division is the propagation of plants from special vegetative organs that separate naturally from the parent plant. Such organs includes:
- Rhizomes e.g ginger
- Suckers e.g. banana and plantain
- Bulbs e.g. onions
- Corm e.g. cocoyam
CUTTINGS: Plants parts are cut into portions in order to produce new plants from them. Cuttings can be obtain from stems, leaves and roots of plants and are used to propagate plants.
- Stem cutting are used to propagate cassava, sweet potato and sugarcane
- Root cutting are used to propagate breadfruit
- Leaf cuttings are used to propagate bryophyllum.
LAYERING is a method of vegetative propagation in which the stems or branches of plants are made to develop roots and give rise to another plan while they are still attached to the parent plant.
GRAFTING is a method of vegetative propagation in which cut surfaces of two different (but closely related) plants are joined together so that they unite and grow as single plants. The lower part of this union is called the stock while the top is called the scion.
BUDDING: It is similar to grafting. Budding involves a desirable characteristic. The bud removed should have a piece of bark attached to it. The removed bud is then inserted into a cut already made in another plant called the stock. The inserted bud is the scion.
ADVANTAGES OF ASEXUAL PROPAGATION
- Plant are true to type, uniform in quality, growth habit and yield
- There is uniformity at maturity
- Is the only way to propagate plants that do not produce seeds
- Plants mature and start beaning fruit early
DISADVANTAGES OF ASEXUAL PROPAGATION
- Plants are usually very rigorous and therefore do not live long enough
- It is not possible to produce new varieties of plants
- Budding and grafting require special skills
- Virus diseases can be transmitted to new plants.