J S S 2

AGRIC SCIENCE NOTE ( cont.) 

(ii). Artificial Methods of vegetative propagation;

These involve the use of cut portions of the parent plant to reproduce new plants. These methods are; 

1. Cutting 

2. Budding 

3. Grafting 

4. Layering

*Plant propagation by seed*

A seed stores its food in the cotyledon (i.e.seed-leaf). Some plants have one seed. leaf; these are called monocotyledon plant. Plants with two seed leaves are called dicotyledon. A cotyledon is an embryonic leaf in a seed-bearing plant. At seedling stage, the seed stores its food in the cotyledon, but when the seedlings stan forming the leaves, the cotyledon drops and the plant begins to manufacture its food through photosynthesis.

*Seed Germination*

Seed germination is the sprouting of a seed usually after a period of dormancy. The process of germination is influenced by water absorption, chilling, warming availability of oxygen, exposure to light and passage of time.

*Types of Germination*

There are two main types of seed Hypogeal germination:germination. These include: 

  (a) Hypogeal germination :This is a type of germination in which the cotyledon remains inside the seed coat and do not come above soil level. eg. monocot plants such as rice, wheat, maize, etc. 

(b) epigeal germination: This is a type of germination in which the cotyledon comes out of the seed coat above the soil level.e.g. onion, bean, castor, etc.

*Conditions necessary for seeds germination*

The conditions that are required for the germination of seeds include:

(a) viable seed;

(b) adequate water/moisture;

(c) adequate temperature;

(d) oxygen/air; and 

(e) sunlight.

*Seed Dormancy*

This is a situation whereby seed fails to germinate due to some factors. A dormant seed is one that is unable to germinate in a specified period of time under normal conditions of germination.

*Factors that cause seed dormancy*

(1) Hard seed coat: This prevents the seed from absorbing water. A seed with hard seed coat can be broken by soaking and scarification.

(2) Immature embryo: Some seeds did not mature during harvesting. Such

seeds will be not be viable for germination.

*Seed Treatment/Seed Dressing*

This is the process whereby farmers coat seeds with chemicals to prevent them from being attacked by pests, and diseases, e.g. fungi. Examples of seed dressing chemicals are 1. Fernasan D

2. Aldrex T etc

Types of asexual propagation

The types of asexual propagation include the following:

1. division;

2. cutting;

3. layering;

4. grafting;

5. budding;

6. marcotting.