Back to: Jss2 Agricultural Science (PVS)

Meaning of Propagation

Propagation refers to the process of spreading or transmitting information, ideas, or beliefs from one person, group, or place to another. It is often used in the context of mass communication, where news or information is disseminated to a large audience through various channels, such as television, radio, newspapers, social media, and other forms of media.

Propagation can also refer to the spread of plants or animals to new areas, either through natural means or human intervention, such as the intentional introduction of a new species into an ecosystem.

Methods of Propagation

There are two types of propagation, these are sexual and Asexual/Vegetative propagation.

Sexual Propagation

The process of Sexual Propagation entails planting crops through the use of seeds. These seeds can either be planted directly in the field or first grown in a nursery before being transplanted. Some examples of seeds that are initially grown in a nursery include oil palm, cocoa, and coconut. Cowpeas (beans), maize, pawpaw, rice, and groundnut, among others, are common crops that are propagated sexually.

When a seed is planted, it undergoes the following processes:

1. Germination: This is the process where the dormant embryo within a seed begins to grow and develop under favourable conditions.
2. Emergence: This term refers to the stage when the seedling breaks through the soil surface and becomes visible above ground level.
3. Seed coat rupture: This is the first step in the germination process, where the seed coat (outer layer) of the seed ruptures, allowing the embryo to emerge.
4. Root growth: Once the embryo has emerged, the root will start growing down into the soil in search of water and nutrients.
5. Shoot growth: Alongside root growth, the shoot will also start growing upwards towards the light, with the cotyledons (first leaves) emerging from the soil.
6. Photosynthesis: As the shoot continues to grow, it will develop leaves and begin to carry out photosynthesis, producing energy and organic compounds that support growth.
7. Reproduction: Once the plant has matured, it will produce flowers or fruit, containing seeds that will restart the life cycle.

Conditions Necessary for Germination of Seeds

The germination of a seed is a complex process that requires a combination of favourable environmental conditions and the presence of the necessary nutrients and hormones. Here are the key conditions necessary for the germination of seeds:

1. Water: Water is essential for seed germination as it initiates the biochemical reactions that lead to the activation of enzymes in the seed. It also softens the seed coat, allowing the seedling to emerge from the seed.
2. Oxygen: Oxygen is essential for the respiration process, which provides energy for the germination process. The embryo of the seed needs oxygen to break down stored food into a form that can be used by the seedling.
3. Temperature: The optimal temperature for seed germination varies depending on the species. Generally, most seeds require a temperature range between 15°C to 30°C. Some seeds require cold stratification, which means they need to be exposed to cold temperatures for a period before germination.
4. Light: Some seeds require light for germination. For example, lettuce seeds need light for germination, while other seeds, like tomato seeds, do not require light.
5. Soil or substrate: The substrate or soil provides support to the seed and the developing seedling. It also contains the necessary nutrients for the seedling to grow.
6. Hormones: Some seeds require specific hormones, such as gibberellins or auxins, to germinate. These hormones play a crucial role in initiating the germination process and promoting the growth of the seedling.

Advantages of Sexual Propagation

Sexual reproduction is a type of reproduction that involves the fusion of male and female gametes to produce offspring. It is the most common method of reproduction in higher organisms. Sexual propagation, in particular, has several advantages over other forms of reproduction, including:

1. Genetic diversity: Sexual reproduction increases genetic diversity, which is beneficial for species’ survival. This diversity helps the species adapt to changing environmental conditions, such as new pathogens or predators.
2. Increased disease resistance: Sexual reproduction increases the chances of producing offspring with greater resistance to diseases, as they have a mixture of genes from both parents.
3. Elimination of harmful mutations: Sexual reproduction can help to eliminate harmful mutations from a population, as they are less likely to be passed on to the offspring.
4. Combination of beneficial traits: Sexual reproduction allows for the combination of beneficial traits from both parents, resulting in offspring with improved abilities, such as increased intelligence or physical prowess.
5. Acceleration of evolutionary change: Sexual reproduction accelerates evolutionary change by producing new genetic combinations that allow for the emergence of new traits and characteristics.
6. Higher adaptability: Sexual reproduction produces offspring with a higher degree of adaptability and flexibility to changing environmental conditions, as they have a wider range of genetic variation.
7. Reduction in genetic inbreeding: Sexual reproduction helps to reduce the likelihood of genetic inbreeding, which can lead to the expression of deleterious traits and reduce the overall fitness of the population.
8. Increased survival rate: Sexual reproduction increases the survival rate of offspring, as they are more likely to inherit a combination of advantageous traits that help them to survive and thrive.
9. Sexual selection: Sexual reproduction allows for the process of sexual selection, where certain traits that enhance reproductive success are favoured by natural selection, leading to the evolution of elaborate physical and behavioural traits.
10. Enhanced coevolution: Sexual reproduction enhances coevolution between species, as it allows for the evolution of specialized adaptations between male and female individuals, leading to coevolutionary arms races between predators and prey or parasites and hosts.

Disadvantages of Sexual Propagation

1. Genetic variation: Sexual reproduction leads to genetic variation, which can result in offspring that are not well adapted to their environment.
2. Time and resources: Sexual reproduction requires more time and resources than asexual reproduction, as it involves the production of gametes and the search for a suitable mate.
3. Limited gene pool: Sexual reproduction involves combining genetic material from two individuals, which can lead to a limited gene pool and reduced genetic diversity.
4. Risk of disease transmission: Sexual reproduction can lead to the transmission of sexually transmitted diseases and infections between individuals.
5. Reduced population growth: Sexual reproduction can result in fewer offspring than asexual reproduction, which can reduce population growth.
6. Inbreeding: Sexual reproduction can lead to inbreeding, which can increase the likelihood of genetic disorders and reduce genetic diversity.
7. Cost of courtship: Sexual reproduction often involves complex courtship rituals, which can be time-consuming and energetically costly.
8. Sexual dimorphism: Sexual reproduction can lead to sexual dimorphism, where males and females have different physical characteristics and behaviours, which can lead to differences in mating success and reproductive output.
9. Competition for mates: Sexual reproduction often involves competition for mates, which can result in aggression, violence, and reduced fitness.
10. Loss of beneficial mutations: Sexual reproduction can result in the loss of beneficial mutations, as they may not be present in both parents or may be masked by deleterious mutations.

Asexual Propagation 

Asexual propagation is a type of plant reproduction that doesn’t involve the production of seeds. Instead, it involves producing new plants using vegetative parts of an existing plant, such as stem cuttings, leaves, or roots. There are several types of asexual propagation, including:

1. Stem cuttings: In this method, a stem from a parent plant is cut and placed in soil or water until roots form and a new plant grows. Examples of plants that can be propagated by stem cuttings include mint, rosemary, and geraniums.
2. Leaf cuttings: This method involves taking a leaf from a parent plant and placing it in soil or water until roots form and a new plant grows. Examples of plants that can be propagated by leaf cuttings include African violet and jade plant.
3. Root cuttings: In this method, a root from a parent plant is cut and placed in the soil until new shoots form and a new plant grow. Examples of plants that can be propagated by root cuttings include horseradish and raspberry.
4. Division: This method involves dividing an existing plant into multiple parts and planting each part separately to grow into a new plant. Examples of plants that can be propagated by the division include hostas and daylilies.
5. Layering: In this method, a stem from a parent plant is bent and covered with soil until roots form and a new plant grows. Examples of plants that can be propagated by layering include strawberries and wisteria.
6. Grafting: This method involves combining a stem or bud from one plant with the rootstock of another plant to create a new plant. Examples of plants that can be propagated by grafting include fruit trees, such as apples and oranges.
7. Bulbs: Bulbs are a type of underground storage organ that contains an embryonic plant, surrounded by layers of modified leaves. When the bulb is planted, the embryonic plant grows and produces a new plant that is genetically identical to the parent plant. Examples of plants that can be propagated by bulbs include daffodils and tulips.
8. Corms: Corms are similar to bulbs in that they are also underground storage organs, but they differ in structure. Corms have a solid centre, whereas bulbs have layers. Corms produce new plants that are genetically identical to the parent plant. Examples of plants that can be propagated by corms include crocuses and gladioli.
9. Suckers: Suckers are shoots that grow from the roots or base of the parent plant. They can be detached and planted separately to produce new plants. Examples of plants that can be propagated by suckers include raspberry and blackberry.
10. Tissue culture: Tissue culture, also known as micropropagation, is a method of asexual propagation that involves growing plant cells or tissues in a laboratory under sterile conditions. This technique allows for the production of large numbers of genetically identical plants in a short period of time. It is commonly used in commercial plant production, particularly for rare or endangered species. Examples of plants that can be propagated by tissue culture include orchids and ferns

Advantages of Asexual Propagation

There are several advantages to asexual propagation, including:

1. Uniformity: Asexual propagation produces plants that are genetically identical to the parent plant, ensuring that they have the same characteristics, including growth rate, colour, size, and shape.
2. Speed: Asexual propagation is faster than sexual reproduction because it does not involve the development of seeds or the fusion of gametes, making it possible to produce large numbers of plants in a shorter time.
3. Precision: Asexual propagation allows growers to reproduce specific plants with desirable traits, such as disease resistance, productivity, or flavour, without the genetic variability that can occur with sexual reproduction.
4. Preservation: Asexual propagation is used to preserve and propagate rare or endangered plant species by maintaining their genetic makeup without introducing new genetic variations.
5. Cloning: Asexual propagation can be used to clone plants with desirable traits, such as high-yielding crops, ornamental plants, or medicinal herbs, allowing growers to maintain consistency in their crop quality.
6. Reduced cost: Asexual propagation can be less expensive than sexual reproduction because it eliminates the need for expensive seed production, pollination, and seedling selection.
7. Adaptability: Asexual propagation allows growers to produce plants that are adapted to specific environmental conditions, such as temperature, humidity, and soil composition, without the variability that can occur with sexual reproduction.
8. Hardiness: Asexual propagation can produce plants that are more resistant to environmental stress, pests, and diseases than plants grown from seed.
9. Consistency: Asexual propagation produces plants that are consistent in quality, size, and growth rate, making it easier to manage crops and predict yields.
10. Ease of propagation: Asexual propagation can be done using simple techniques, such as stem cuttings, layering, and division, making it accessible to small-scale growers and hobbyists.

Disadvantages of Asexual Propagation

1. Lack of genetic diversity: Asexual propagation produces plants that are genetically identical to the parent plant, which means that there is no genetic variation among the offspring. This lack of genetic diversity can make plants more susceptible to diseases and pests.
2. Limited adaptation: Since the offspring of asexual propagation are genetically identical to the parent plant, they may have limited adaptation to changing environmental conditions. This could result in reduced vigour and lower yields.
3. Vulnerability to pests and diseases: Asexual propagation produces plants that are genetically identical, which means that if a pest or disease affects one plant, it can easily spread to all the other plants.
4. Limited propagation potential: Some plant species are difficult to propagate asexually. This can limit the potential for asexual propagation and require other methods of propagation.
5. High labour costs: Asexual propagation can be labour-intensive since it involves cutting, rooting, and transplanting individual plant parts. This can increase the cost of production, especially for large-scale operations.
6. Slow propagation: Asexual propagation can take longer than other methods of propagation, such as seed propagation, which can limit the number of plants that can be produced in a given timeframe.
7. Limited genetic improvement: Asexual propagation does not allow for the genetic improvement of plants. This means that desirable traits cannot be easily bred into the plants.
8. Limited seed production: Asexual propagation produces plants that do not produce seeds, which means that the only way to propagate the plants is through asexual means.
9. Incompatibility: Some plants may be incompatible with asexual propagation methods, which can limit the potential for this method of propagation.
10. Risk of genetic degeneration: Over time, asexual propagation can result in genetic degeneration, where the genetic material of the plants becomes less stable and less viable. This can result in lower yields and reduced plant health.

Project/Practical

Cultivate a variety of plants such as beans, aloe vera, maize, water leaf, corchorus (ewedu), amaranthus (efo), and okra, by choosing to propagate them through either sexual or asexual means.

Sexual propagation involves the use of seeds, which can be sown in a seed pot filled with nutrient-rich soil. To begin, select the appropriate seeds, soak them in water for a few hours, and then plant them in the soil. Be sure to follow the instructions on the seed packet for the appropriate planting depth and spacing. After planting, water the soil thoroughly and place the pot in a warm and well-lit area. With proper care, the seeds will germinate and grow into healthy plants.

Asexual propagation, on the other hand, involves using plant parts such as stems, leaves, or roots to create new plants. To propagate plants asexually, select a healthy and mature plant and take a cutting of the stem or leaf. Dip the cut end into a rooting hormone powder and plant it into a seed pot filled with nutrient-rich soil. Water the soil thoroughly and place the pot in a warm and well-lit area. The cutting will develop roots and grow into a new plant.

While both methods of propagation have their advantages and disadvantages, it is important to choose the method that works best for the specific plant and situation. Regardless of the method used, regular watering, proper fertilization, and adequate lighting are essential for the growth and development of the plant. With patience and care, your plants will thrive and provide you with fresh produce or beautiful foliage.