Crop propagation refers to the art and science of forming new plants. A method of propagation is considered successful if it can transmit desirable characteristics from the mother plant to the offspring. There are two main ways of propagating crops. They are:
- By use of seeds
- By use of vegetative materials
Let's learn more about these two ways of crop propagation.
LEARNING OBJECTIVES
By the end of this topic, you should be able to:
- Explain the methods of crop propagation using seeds and vegetative materials
- Describe the advantages and disadvantages of using seeds and vegetative materials for propagation
- Explain the factors considered when selecting planting materials
- Tell the different plant parts used in vegetative propagation
Crop Propagation Using Seeds
This is the production of new plants through the use of seeds. A seed is a unit of reproduction in plants capable of developing into a plant. Seeds germinate and grow into new plants.
Advantages of using seeds in crop propagation
- Seeds are convenient to handle, store and transport.
- Seed propagation introduces new varieties, particularly in cross a pollinated plants.
- They are relatively cheap.
- They are the only possible method of propagating certain crops like beans and maize.
- Seed propagation requires less skill.
- Mechanization is easy when using for propagation.
- Treatment against diseases and pests is easy.
- Seeds can be stored for relatively long periods of time.
Disadvantages of using seeds in crop propagation
- Some seeds do not breed true to type, like hybrid seeds.
- Some seeds have prolonged dormancy and juvenile periods, hence take longer to mature.
- There is a loss of heterosis or hybrid vigor, mainly in cross-pollinated plants.
- Some seeds have low viability or are not viable at all.
- It is highly dependent on the process of pollination and fertilization.
- Seed propagation can spread undesirable traits in a plant population.
Using Certified seeds
These are seeds that are produced under certain standards by registered seed growers under the supervision of agricultural research organizations or by the government. The aim of seed certification is to ensure genetic purity and physical quality of seeds, therefore adding value to the seeds and improving their marketability.
Advantages of using certified seeds in crop propagation
- They have higher germination potential.
- They are free from pests and diseases.
- They give high yields.
- They are able to adapt to certain ecological conditions easily.
- They are free from physical damage.
- They are bred true to type.
- They are free from foreign materials.
Crop Propagation Using Vegetative materials
These are plant parts that can grow and develop into new plants. They include roots, stems, and leaves. These materials are induced to form roots and shoots depending on the plant part being used.
Plant parts used in vegetative propagation
Slips - They are used to propagate crops like pineapples. They are borne at the base of pineapple fruit and then cut for planting.
Crowns - These can be used also in the propagation of pineapples. They are borne at the top of pineapple fruit and are broken off for planting.
Suckers - They are used to propagate crops like sisal, bananas, and pineapples. They are small plants with adventitious roots growing from the base of the main stem.
Vines - These are soft cuttings obtained from mother plants and planted directly into the main field to give rise to new plants. They are used in the propagation of sweet potatoes.
Splits - They are obtained by splitting the mother plant into plantlets with complete leaves and rooting systems. They are mainly used to propagate pasture grasses.
Tubers - These are underground food storage organs that sprout to grow into new plants. There are two major types of tubers;
- root tubers like sweet potatoes;
- stem tubers like Irish potatoes.
Bulbils - These are tiny plants produced in the inflorescence towards the end of the growth cycle, mainly in sisal.
Cuttings - These are plant portions (roots, leaves, or stems) that are cut and then planted. They have buds that develop into a shoot.
Advantages of using vegetative materials in crop propagation
- It is completely independent of the process of pollination and fertilization.
- It is possible to maintain desirable characteristics such as disease resistance and physical appearance.
- It is a quicker method of propagating crops as the juvenile period is shortened.
- It makes it possible to propagate crops that are seedless or have less viable seeds.
- The growth habit of a crop can be regulated to attain a desirable size and shape.
- Vegetative propagation imparts desirable characteristics to crops, like seedlessness in citrus fruits.
Disadvantages of using vegetative materials in crop propagation
- This method is not useful when breeding new varieties due to the lack of genetic variation of offspring.
- It is difficult to store vegetative materials for a long time.
- Undesirable qualities and diseases may be passed on to the offspring.
- Vegetative materials are bulky, and therefore difficult and expensive to handle, store and transport.
Factors considered when selecting planting materials
- Size and shape of the material.
- The suitability or adaptability of the material to the ecological conditions of the area.
- Health and purity of the material.
- Age or maturity of the material.
- Disease resistance of the material.
- Qualities of the parent plant like high yielding, vigorous growing, and germination percentage.
