The rapidly growing human population has created an ever-increasing demand for food. To feed the billions of people on Earth, it is essential to enhance food production from both agriculture and animal husbandry. The chapter deals with the strategies and technologies used to increase the production of food, both plant and animal based. The main approaches are the improvement of crop varieties through plant breeding, the enhancement of animal breeds through animal breeding, and the intensive use of microorganisms for the production of food and feed.
The Green Revolution in the 1960s and the White Revolution (Operation Flood) transformed India from a food-deficient country to a self-sufficient one. These achievements were possible through the scientific improvement of crop plants, the development of high-yielding varieties, and the improvement of dairy animals. This chapter covers plant breeding techniques, tissue culture and hybridisation for crop improvement, and the methods of animal breeding, along with the management of dairy animals and poultry. A modern perspective also includes the use of biofortification and the development of genetically modified crops.
Plant breeding is the science of improving the genetic makeup of crop plants to make them more useful to humans. It is the purposeful manipulation of plant species to create desired plant types that are better suited for cultivation, give better yields, and are disease resistant.
The main objectives are: - Higher yield: To increase the quantity of produce per unit area. - Improved quality: Better nutritional quality and consumer appeal. - Disease resistance: Resistance to pests, bacteria, viruses and fungi. - Stress tolerance: Tolerance to drought, salinity, heat and cold. - Early maturity: Shorter growing periods. - Wider adaptability: Ability to grow in a range of environments.
The classical plant breeding involves the following steps: 1. Collection of genetic variability: Collecting and preserving all the diverse wild varieties, species and relatives of the crop plant. This genetic variability is the raw material for breeding. 2. Evaluation and selection of parents: Evaluating the collected germplasm to identify the parents with desirable traits. 3. Cross hybridisation: Crossing the selected parents to combine the desirable traits from both. This is the most tedious step because a large number of crosses have to be made to identify the desirable combinations. 4. Selection and testing of superior recombinants: Selecting the plants with the desired traits from the progeny and testing them for yield, disease resistance and other traits. 5. Testing, release and commercialisation: Testing the new variety for agronomic traits and quality, then releasing it for cultivation by farmers after approval.
Hybridisation is the crossing of plants with different genetic constitution. Depending on the parents involved, hybridisation can be: - Intervarietal (between different varieties of the same species). - Interspecific (between different species of the same genus). - Intergeneric (between different genera).
The hybrid vigour (heterosis) refers to the superior performance of the hybrid over both parents.
Polyploidy is the presence of more than two sets of chromosomes in a cell. Some crop plants have been improved by polyploidy. For example, the intergeneric hybrid between radish (Raphanus) and cabbage (Brassica), called Raphanobrassica, was developed. However, polyploidy has been more successful in ornamental plants than in crop plants.
Biofortification is the development of crops with higher levels of vitamins, minerals, proteins and healthier fats. The objective is to improve the nutritional quality of food. Examples include: - Iron and zinc enriched wheat varieties. - Protein enriched maize and beans. - Vitamin A enriched rice and carrots. - Oil with higher content of healthier fatty acids.
Tissue culture is the technique of growing plant cells, tissues or organs in an artificial culture medium under aseptic conditions. A whole plant can be regenerated from a single cell or explant through a process that exploits the totipotency of plant cells, which is the ability of a cell to develop into a complete organism.
In tissue culture, a small piece of plant tissue (explant) is placed on a nutrient medium containing hormones (auxins and cytokinins) and grown aseptically. The cells proliferate to form a callus, which is then induced to form shoots and roots, producing plantlets. These plantlets are transferred to soil. The advantages of tissue culture are: - Rapid multiplication of elite plants (micropropagation). - Production of virus-free plants. - Production of soma clones (genetically identical plants). - Propagation of rare or endangered species. - Conservation of germplasm.
Single cell proteins (SCP) are the proteins produced by microorganisms like bacteria, fungi and algae, which can be used as a protein-rich supplement in the human diet and animal feed. The main advantage of SCP is that microorganisms grow rapidly and can be grown on industrial wastes, sewage, and other cheap substrates. Examples include Spirulina (a blue-green alga), which can be grown easily on materials like straw, molasses, animal manure and even sewage, making it a rich source of protein. Members of the genus Methylophilus (a bacterium) are grown on methanol to produce SCP for cattle.
The production of SCP has several advantages: it can be produced throughout the year in reactors, has high nutritional value, does not require large areas of land, and helps in the disposal of waste materials.
Animal husbandry is the scientific management of animals for the production of milk, eggs, meat, wool and other products. It includes the care, breeding and management of livestock, including cattle, poultry, fish and bees.
The dairy industry involves the management of milch animals like cows, buffaloes, goats and sheep. The improved breeds are obtained by crossing indigenous and exotic breeds. For example, the crossbred cattle like Karan Fries and Frieswal have been developed by crossing Friesian with Sahiwal or other Indian breeds. Management practices include adequate feeding, clean and hygienic shelter, disease control, and proper milking and storage of milk. The White Revolution (Operation Flood) in India, started by Dr. Verghese Kurien, transformed the dairy industry through the establishment of cooperatives.
Poultry farming is the raising of chickens, ducks, turkeys and geese for meat and eggs. The improved breeds of poultry (e.g., the improved layer and broiler breeds) give more eggs and meat. Broiler chickens are raised for meat, while layers are raised for eggs. Poultry farming requires proper management of housing, feeding, disease control and hatchery.
Bee keeping is the maintenance of beehives for the production of honey. Honey is a source of food, and bees also help in pollination of plants. The common varieties of bees used are Apis dorsata, Apis florea and Apis indica (also called Apis cerana indica). The improved Italian bee, Apis mellifera, is also used because it has a high honey collection capacity, stings less, and multiplies rapidly. The quality of honey depends on the flowers visited by the bees.
Fisheries involve the breeding, catching and selling of fish, molluscs and crustaceans. Marine fish include hilsa, sardines, mackerel and tuna, while freshwater fish include rohu, catla and mrigal. Aquaculture is the practice of culturing fish in ponds and other water bodies. Pisciculture is the culture of fish, and pearl culture is the culture of pearl-producing oysters.
Animal breeding is the production of improved breeds of animals through controlled reproduction and mating. The objectives are to improve the yield of milk, eggs, meat, wool and to develop animals with desirable characteristics.
Artificial insemination is the technique of injecting semen from a superior male into the reproductive tract of a female. The advantages are: - The semen of a superior male can be used to inseminate many females, increasing the rate of improvement. - Semen can be stored for long periods and transported. - It overcomes the limitations of natural mating.
MOET is a method of improving dairy cattle that involves superovulation, in which a cow is administered hormones to produce many eggs instead of one. The eggs are fertilised artificially, and the embryos are collected and transferred to surrogate mothers. This technique has been used in India for programmes like Varun and Suruchi to improve the milk yield of cattle.
| Step | Activity |
|---|---|
| 1 | Collection of genetic variability |
| 2 | Evaluation and selection of parents |
| 3 | Cross hybridisation |
| 4 | Selection and testing of superior recombinants |
| 5 | Testing, release and commercialisation |
| Type | Definition | Example/Use |
|---|---|---|
| Inbreeding | Mating of closely related individuals | Increases homozygosity |
| Out-crossing | Unrelated animals of same breed | Removes undesirable traits |
| Cross-breeding | Different breeds of the same species | Combine desirable traits |
| Interspecific hybridisation | Different species | Mule (donkey + horse) |
| MOET | Embryo transfer after superovulation | Improve dairy cattle |
| Technology | Description | Example |
|---|---|---|
| Plant breeding | Improvement of crop genetics | Semi-dwarf wheat, IR-8 rice |
| Biofortification | Improving nutritional quality | Iron-enriched wheat, vitamin A rice |
| Tissue culture | Growing plants from cells/tissues | Micropropagation, virus-free plants |
| Single cell proteins | Protein from microbes | Spirulina |
| Apiculture | Honey production | Apis mellifera |
Strategies for enhancement in food production are among the most directly beneficial applications of biology, addressing the fundamental need to feed a growing population. Classical plant breeding, which follows a systematic sequence from the collection of genetic variability to the release of new varieties, produced the Green Revolution and continues to develop disease resistant, stress tolerant and high yielding crops. Modern techniques such as biofortification and tissue culture, along with single cell proteins, add nutritional value and sustainability to food production. In animal husbandry, scientific breeding through inbreeding and outbreeding, artificial insemination and MOET have improved the productivity of dairy, poultry, fishery and apiculture. The achievements of the White Revolution stand as a testament to the power of applied animal management. Together, these strategies ensure food security and prepare the ground for the genetic engineering techniques discussed in the biotechnology chapters.