In this article, we shall study asexual reproduction in plants.

Reproduction:

Reproduction is defined as a biological process in which an organism gives rise to young ones (offspring) similar to itself. The offspring grow, mature and in turn produce new offspring. Thus, there is a cycle of birth, growth and death. Reproduction enables the continuity of the species, generation after generation.

Types of Reproduction:

• Asexual Reproduction: When offspring is produced by a single parent with or without the involvement of gamete formation, the reproduction is asexual.
• Sexual Reproduction: When two parents (opposite sex) participate in the reproductive process and also involve the fusion of male and female gametes, it is called sexual reproduction.

Characteristics of Asexual  Reproduction

• In this method, a single individual (parent) is capable of producing offspring. A
• As a result, the offspring that are produced are not only identical to one another but are also exact copies of their parent.
• These offspring are genetically and morphologically identical to parents
• The term clone is used to describe such morphologically and genetically similar individuals.
• Usually followed by organisms with relatively simpler organizations

Types of Asexual  Reproduction:

Binary Fission:

In Protists and Monerans, the organism or the parent cell divides into two to give rise to new individuals. Thus, in these organisms cell division is itself a mode of reproduction. Many single-celled organisms reproduce by binary fission, where a cell divides into two halves and each rapidly grows into an adult. e.g., reproduction in Amoeba, Paramecium, Viruses.

Budding:

In yeast, the division is unequal and small buds are produced that remain attached initially to the parent cell which, eventually gets separated and mature into new yeast organisms (cells). e.g reproduction in  Yeast and hydra.

Spores Formation:

Members of the Kingdom Fungi and simple plants such as algae reproduce through special asexual reproductive structures. The most common of these structures are zoospores that usually are microscopic motile structures. Other common asexual reproductive structures are conidia (Penicillium), buds (Hydra) and gemmules (sponge).In fungi and algae, specialized asexual reproductive units are formed.

Natural Methods of Vegetative Propagation (Asexual reproduction):

Vegetative Propagation is an asexual method of reproduction in plants. In plants, the units of vegetative propagation such as runner, rhizome, sucker, tuber, offset, bulb are all capable of giving rise to new offspring. These structures are called vegetative propagules. Since the formation of these structures does not involve two parents, the process involved is asexual.

Tuberous Roots:

The roots of such plants have adventitious buds on their surface which sprout under favourable conditions to produce leafy shoots. In Commercial Production these sprouts are separated and planted. Thus many plants can be obtained from a single root. e.g. Sweet potato, Asparagus (Shatavari), Dahlia.

Stem Tubers:

A stem tuber has many notches called ‘eyes’ on their surface. Each eye actually a node and consists of one or more small axillary buds and reduced scale leaves. After dormancy period the eyes which sprout under favourable conditions to produce leafy shoots.

In Commercial Production the tuber is cut into pieces, such that each piece has at least one eye. Then they are grown separately. Thus many plants can be obtained from a single tuber. e.g. Potato, Ginger.

Runners:

Runner develops from the lower axillary bud of the stem and thin elongated cylindrical wire-like structure with long internodes. It creeps on the ground and becomes rooted at the nodes. Shoots are produced from the upper sides of nodes. After getting detached from a parent, such shoots grow as an independent plant. e.g. Cynodon (doobgrass), Fragaria (strawberry), Oxalis.

Leaf:

In bryophyllum, the leaf is succulent with crenate or notched margins. Adventitious buds called epiphyllous buds or foliar buds are formed at notches at the tip of lateral veins. These buds sprout and form leafy shoots and adventitious roots. When such sprout falls on wet soil, they develop into independent plants. e.g. Bryophyllum, Kalanchoe, Begonia.

Hazard due to Water Hyacinth (Terror of Bengal)

• One of the most invasive weeds
• Grows wherever there is standing water
• Drains oxygen from water- leads to the death of fishes.
• Introduced in India because of its pretty flowers & shape of leaves
• Vegetative propagation occurs at a phenomenal rate

Artificial Methods of Vegetative Propagation  (Asexual reproduction):

Vegetative methods offer many advantages. As the new generation produced by asexual reproduction is exactly the same as the parent (clone), the good qualities of a race or variety can be preserved indefinitely. If plants have poor viability or prolonged seed dormancy, then vegetative propagation is a rapid, easier and less expensive method of multiplying plants.

The process of growing plants using artificial methods is called artificial propagation.

Layering:

In this method, a young branch is bent and pressed into moist soil. After some time roots develop from the covered part. This is called a layer. Now the branch can be cut from the parent and a new plant is produced. This method is used to propagate plants such as jasmine, black raspberries.

Cutting:

In this method, a branch of plant part (stem, root or leaves) is cut with a node (primary meristem) on it. This piece of a branch is termed a cutting. This cutting is buried in the soil and is watered continuously. This method is the cheapest and convenient method of vegetative propagation.

Grafting:

In this method, the parts of two different plants are joined together in such a way that they unite and continue their growth as one plant. The plant rooted in the soil and on which the part of the other plant is inserted is called a stock. The other plant which is inserted on the stock is called Scion or graft. Budding is a special case of grafting in which a single bid with a small part of bark and living tissue is grafted on another plant.

Tissue culture:

This is a modern method of vegetative reproduction. In this method, a piece of tissue is cut from the plant the removed tissue is called explant. The explant is kept in a nutrient medium under controlled condition. This tissue grows into a mass of cells called a callus. Cells of callus are separated and each cell can give a new plant. These cells are called plantlets.  Now the plantlets are grown in a pot of soil. Plants like chrysanthemum and orchids have been propagated by this method.

The significance of Vegetative Propagation:

• It is easy and cheaper method of multiplication.
• The plants like banana, pineapple and grapes which do not produce viable seeds can be propagated by vegetative propagation only.
• In this method, genetically similar plants are formed.
• The yield can be increased by grafting high-yield variety on less yielding variety but which is adapted to the region.
• This is a rapid method of propagation particularly for the plants having a long dormancy period.
• It can be used to get clones of rare plants.

Science > Biology > Botany > Reproduction in Plants > Asexual Reproduction in Plants

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In the previous article, we have studied the importance of biology. In this article, we shall study different branches of biology.

On the Basis of Kind of Organism:

Depending upon the kind of organism, the branches of biology are as follows:

• Botany: Botany is the scientific study of plants which include algae, fungi, lichens, mosses, ferns, conifers, and flowering plants.
• Zoology:  Zoology involves the study of animals including their classification, their history, their anatomy, and physiology,
• Microbiology: Microbiology is the study of all living organisms that are too small to be visible to the naked eye. This includes bacteria, archaea, viruses, fungi, prions, protozoa, and algae, collectively known as ‘microbes’.
• Human Biology: Human biology is the branch of biology that deals with human beings and human populations. It includes all the aspects of the human as an organism including genetics, ecology, anatomy and physiology, anthropology, and nutrition. Human biology is related to other fields of biology such as medicine, primate biology, and biological anthropology.

On the Basis of Group of Organisms:

Depending upon the group of organisms under the study, the branches of biology are as follows:

• Bacteriology: The science and study of bacteria and their relation to medicine and to other areas such as agriculture (e.g., farm animals) and the industry is called Bacteriology.
• Virology: Virology is the study of viruses and virus-like agents, including (but not limited to) their taxonomy, disease-producing properties, cultivation, and genetics. It is often considered a part of microbiology or pathology.
• Mycology: Mycology is the branch of biology that deals with the study of fungi. It includes the research of their genetic and biochemical properties and their use in medicine and food along with their hazards.
• Entomology: Entomology is a branch of zoology that studies insects and how they interact with their environment, other species and humans.
• Ichthyology: Ichthyology is the branch of zoology devoted to the study of fishes, which includes bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha).
• Herpetology: Herpetology is the branch of zoology concerned with the study of amphibians,  reptiles. Batrachology is a further subdiscipline of herpetology concerned with the study of amphibians only.
• Ornithology: Ornithology is the scientific field dedicated to the study of birds.

On the Basis of Approach to Study:

Depending upon the approach of the study, the branches of biology are as follows:

• Anatomy: It is the scientific study focusing on the physical structures and parts of organisms (plants and animals).
• Morphology: Morphology is a branch of biology dealing with the study of the form and structure (internal and external)  of organisms and their specific structural features
• Histology: Histology is the scientific study of the fine detail of biological cells and tissues using microscopes
• Cytology: The study of structure and function of plant and animal cells.
• Physiology: The branch of biology dealing with the functions and activities of living organisms and their parts, including all physical and chemical processes is called physiology.
• Embryology: Embryology is the study of the development of an embryo from the stage of ovum fertilization through to the fetal stage.
• Taxonomy or Systematics: The science of identifying, naming, grouping and classifying plants and animals is called taxonomy or systematics.
• Ecology: Ecology is the scientific study of the interactions between organisms and their environment.
• Biogeology: The study of the interaction between the Earth’s biosphere and the lithosphere.
• Biogeography: Biogeography is a study of the distribution of various species and ecosystems geographically and throughout geological time and space.
• Paleontology:  the study of fossils to determine the structure and evolution of extinct animals and plants and the age and conditions of deposition of the rock strata in which they are found is called Palaeontology.
• Evolution: evolution is the branch of biology which studies the change in the characteristics of a species over several generations and relies on the process of natural selection.
• Genetics: Genetics is a branch of biology that deals with heredity and variations.
• Parasitology: Parasites are those organisms that live on or inside other organisms called the host and draw nourishment from the host are called parasites. The study of parasites is called parasitology. It includes the study of three major groups of animals: parasitic protozoa, parasitic helminths (worms), and those arthropods that directly cause disease or act as vectors of various pathogens.
• Pathology: It is a branch of biology which studies diseases in plant and animals and their treatment.
• Immunology: The immune system protects us from infection through various lines of defense. Immunology is the study of the immune system.
• Eugenics: The study of or belief in the possibility of improving the qualities of the human species or a human population, especially by such means as discouraging reproduction by persons having genetic defects or presumed to have inheritable undesirable traits. Thus it is a science which aims to improve the human race through controlled heredity.
• Biochemistry: Biochemistry is the study of the processes behind all living organisms,

On the Basis of Agriculture and Allied Industries:

With respect to agriculture and allied industries, the branches of biology are as follows:

• Agriculture: It is a branch of biology which deals with raising crops and live stocks such as cows, buffaloes, etc.
• Veterinary Science:  The branch of medicine that deals with the causes, diagnosis, and treatment of diseases and injuries of animals, especially domestic animals.
• Marine Biology: Marine biology is the study of marine organisms, their behaviours, and their interactions with the environment.
• Horticulture: Horticulture is the science and art of producing, improving, marketing, and using fruits, vegetables, flowers, and ornamental plants.
• Animal Husbandry: It is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, eggs, or other products. It includes day-to-day care, selective breeding and the raising of livestock like cows, buffaloes, etc.
• Sericulture: Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk.
• Pisciculture: The breeding, rearing, and transplantation of fish by artificial means is called pisciculture.
• Tissue Culture: Tissue culture, a method of biological research in which fragments of tissue from an animal or plant are transferred to an artificial environment in which they can continue to survive and function.
• Molecular Biology: Molecular biology is a branch of science concerning biological activity at the molecular level. The field of molecular biology overlaps with biology and chemistry and in particular, genetics and biochemistry.
• Biotechnology: Biotechnology is the use of biological processes, organisms, or systems to manufacture products intended to improve the quality of human life.
• Cloning: Cloning is a process of asexual reproduction to create offspring that are genetically identical to the parent.
• Bioengineering: It is the branch of biology which with the help of engineering science help in making artificial limbs, joints and other parts of the body using engineering materials and techniques. It also includes the improvement of crops for disease resistance and yield.
• Biomedical Engineering: Biomedical engineering is the application of engineering principles to the fields of biology and health care. Biomedical engineers work with doctors, therapists and researchers to develop systems, equipment, and devices in order to solve clinical problems. The job includes the design, development, production, and maintenance of medical instruments.
• Nuclear biology: Nuclear biology or radiobiology is a branch of biology which studies the effect of radioactivity on living cell and also deals with the development and production of nuclear medicines for diagnosis and treatment of the diseases.
• Space Biology: The study of the survival of living things in a space is called space biology.
• Genomics: Genomics is a study of the genomes of organisms. Its main task is to determine the entire sequence of DNA or the composition of the atoms that make up the DNA and the chemical bonds between the DNA atoms.
• Bioinformatics: Bioinformatics is the application of information technology to the study of living things, usually at the molecular level. Bioinformatics involves the use of computers to collect, organize and use biological information to answer questions in fields like evolutionary biology.
• Biometrics: Biometrics is a technological and scientific authentication method based on biology and used in information assurance (IA). Biometric identification authenticates secure entry, data or access via human biological information such as DNA or fingerprints.
• Forensic science: The forensic sciences are used around the world to resolve civil disputes, to justly enforce criminal laws and government regulations, and to protect public health. The field of forensic science depends on other branches of science, including physics, chemistry, and biology, with its focus being on the recognition, identification, and evaluation of physical evidence. It has become an essential part of the judicial system to achieve information relevant to criminal and legal evidence.
• Genetic Engineering: Genetic engineering refers to the direct manipulation of DNA to alter an organism’s characteristics (phenotype) in a particular way.

On the Basis of Medical Sciences:

On basis of medical sciences, the branches of biology are as follows:

• Gynecology and Obstetrics: Gynaecology normally means treating women who aren’t pregnant, while obstetrics deals with pregnant women and their unborn children, but there is lots of crossover between the two.
• Orthopedics: It is a branch of medical science which is devoted to the diagnosis, treatment, prevention, and rehabilitation of injuries, disorders, and diseases of the body’s musculoskeletal system. This system includes bones, joints, ligaments, muscles, nerves, and tendons.
• Opthalmology: It is the branch of medicine that deals with the anatomy, physiology, and diseases of the eyeball and orbit.
• Dentistry: It is a branch of medicine that consists of the study, diagnosis, prevention, and treatment of diseases, disorders, and conditions of the oral cavity.
• Oncology: Oncology is the branch of medicine that researches, identifies and treats cancer.
• Cardiology: Cardiology is a branch of medicine that concerns diseases and disorders of the heart, which may range from congenital defects through to acquired heart diseases such as coronary artery disease and congestive heart failure.
• Urology: Urology is a surgical specialty that deals with the treatment of conditions involving the male and female urinary tract and the male reproductive organs.
• Nephrology: Nephrology is a branch of medical science that deals with diseases of the kidneys.
• Pediatrics: Pediatrics is the branch of medicine dealing with the health and medical care of infants, children, and adolescents from birth up to the age of 18.
• Dermatology: Dermatology is the branch of medicine dealing with diagnosing and treating skin diseases affecting the skin, hair, and nails.
• Physiotherapy: Physiotherapy is a branch of medicine which uses a treatment method that focuses on the science of movement and helps people to restore, maintain and maximize their physical strength, function, motion and overall well-being by addressing the underlying physical issues.

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