Introduction:
Food is necessary for the development and survival of all the organisms. To deal with the need of food with the increasing population, it is necessary to increase food production.There are so many technologies which increase yield such as plant breeding, animal husbandry and modern technologies like tissue culture, genetic engineering, embryo transfer. An improved variety can be produced by three methods only:
1. Plant breeding: Classical, less efficient and time consuming
2. By induced mutation and by selecting improved mutants.
3. By genetic engineering
Main Steps Required for Developing New Varieties:
1. Collection of variability: Main reason behind breeding is genetic variability. In many crops pre-existing genetic variability is available from wild relatives of the crop. Germplasm is collected from the same country or from other countries and they are usually maintained at low temperature in the form of propagules. The stored propagules are periodically grown in the field to obtain fresh propagules. Germplasm is the sum total of all the alleles for all the genes present in the crop and its related species.
2. Evaluation and selection of parents: the germplasm is evaluated so as to identify plants with desirable combinations of characters. Selection of parents is done by picking up seeds of only those plants which have desired traits. These selected plants are multiplied and used in the process of hybridisation.
3. Hybridisation: Hybridisation is a process of making cross between two genetically diverse parents to obtain a progeny with desired superior traits.
4. Selection and testing of superior recombination: This step comprises selecting, among the progeny of the hybrids, i.e those plants that have the desired character combination. This is the crucial step for the success of breeding objectives and requires careful scientific evaluation of progeny. Selection is again done in new plants and further selection is of three types:
Mass Selection: It is one of the simplest and oldest methods mainly used in cross pollinated crops and is based on phenotypic characters. One of the oldest methods of crop improvement.
Pure Line/ Inbreed Selection: Involves isolation of desirable homozygous individuals and is done for self pollinating crops. It is the progeny of a single homozygous self pollinated plant. In this method a plant of desired characters is selected by a genetically mixed population.
Colonel Selection: It is used for vegetative reproducing crops. Clones are known to be progeny of a single vegetatively propagated plant. Here selection is made between clones not within clones. Example: Kufri safed potato.
5. Testing, release and commercialisation of new cultivators: Evaluation of newly selected lines is done and further they undergo quality, disease resistance, and many more tests.
Aims of Plant Breeding:
A. Plant breeding for disease resistance: Fungal, bacterial, viral and nematode pathogens attack the cultivated crops. So crop loss can be upto 20-30 percent, sometimes even total. In such situations crops are made disease resistant, food production is increased and use of fungicides and bactericides would be reduced.
Methods of Breeding for Disease Resistance:
Screening germplasm for resistance sources: Wild plants can be the best source because they survive without getting protection from humans in any environment. Their characters are useful for plant breeders: for example potato.
Hybridisation of selected parents.
Selection and evaluation of hybrids.
Testing and release of new varieties.
B. Plant breeding for developing resistance to insects/pests: Insects and pest infection is another major cause for large destruction. Insect resistance in host plants is due to morphological, biochemical and physiological characters. Smooth leaves cotton varieties do not attract bollworms.
C. Plant breeding for improved quality: It is estimated that more than 840 million people in the world do not have adequate food to meet their daily requirements. Breeding of crops with higher levels of vitamins and minerals or higher proteins and healthier fats is called biofortification.
Mutation Breeding:
Mutation is sudden, stable and heritable change which alters the gene expression of the organism.This results in a new character not found among parents. The mutation, which are artificially induced mutations for crop improvement is called mutation. The agents which are used to induce mutation for crops improvement is called mutation breeding. Which are used to induce mutations are called mutagens. Various chemicals such as HNO₂, base analogues, acridine dyes, and physical agents such as x-rays, uv rays and gamma rays.
Polyploid Breeding:
Organisms having more than two sets of chromosomes are called polyploid. Induced polyploidy is used by plant breeders for improving yield of forage and other crops. Many modern crops such as wheat, rice, sugarcane, potato and cotton are natural polyploids.
Single Cell Protein (SCPs):
The cells from microorganisms such as bacteria, yeasts, filamentous algae, treated in various ways and used as food are called single cell proteins. They are processed to remove excess nucleic acid. The raw material for single cell protein production include whey, sulphite waste liquor, hydrocarbon waste from petroleum industry, waste water containing scratch from potato processing plants, straw, molasses and animal manure.
Energy Crop:
It is a manure prepared from young, green crops which can be used for production of alcohol are potato, sugar beet, tapioca and molasses of the sugar industry. Growing crops for production of alcohol and other fuel is known as energy cropping.
Plant Tissue Culture:
This is one of the latest and most promising methods of crop improvement in such plants, where all other conventional methods of breeding fail. It is based on the totipotent nature of plant cells. Plant tissue culture is the technique of maintaining and growing plant cells, tissues and organs in sterilised culture medium, under controlled aseptic conditions.
Types of Culture:
Callus culture and suspension culture
Meristem culture
Embryo culture
Anther culture
protoplast culture
Green Manure:
It is a manure prepared from young, green crop plants by ploughing them back into soil. For example sunn Hemp (crotalaria juncea), Dhaincha (Sesbania aculeata), Cluster Bean (Cyamopsis tetragonoloba), sweet Clover, Lentil.
FAQs on Strategies for Enhancement in Food Production
1. What are the main objectives of plant and animal breeding as part of the strategies for enhancement in food production?
The primary objective for both plant and animal breeding is to improve the quality and yield of food sources. Key goals include:
- Increased Yield: Developing varieties of crops and breeds of animals that produce more food per unit.
- Improved Quality: Enhancing nutritional value (e.g., protein content in wheat, better meat quality), taste, or storage life.
- Resistance to Diseases: Creating varieties that are resistant to common viral, fungal, and bacterial pathogens to reduce crop and livestock loss.
- Tolerance to Environmental Stresses: Breeding for tolerance to extreme conditions like salinity, drought, and high temperatures.
2. For the CBSE 2025-26 board exam, what are the five essential steps in a classical plant breeding program for creating a new genetic variety of a crop?
A conventional plant breeding program involves a systematic, five-step process that is a very important topic for exams. The steps are:
- Collection of Variability: The foundation of any breeding program is the collection and preservation of all different wild varieties, species, and relatives of the cultivated species. This is known as germplasm collection.
- Evaluation and Selection of Parents: The collected germplasm is evaluated to identify plants with desirable combinations of characters. These selected plants are then multiplied and used in the process of hybridisation.
- Cross Hybridisation among Selected Parents: The desired characters are combined from two different parents. For example, a high-protein quality parent is crossed with a disease-resistant parent to create a hybrid with both traits.
- Selection and Testing of Superior Recombinants: The selection process is crucial to screen the progeny of the hybrids. It involves selecting those plants that have the desired character combination. This requires careful scientific evaluation.
- Testing, Release, and Commercialisation of New Cultivars: The newly selected lines are evaluated for their yield and other agronomic traits of quality, disease resistance, etc., in research fields and then in farmers' fields for at least three growing seasons. If successful, they are released as a new cultivar.
3. A farmer observes reduced fertility and productivity in his cattle herd after several generations of mating closely related superior animals. What is this phenomenon called, and what breeding strategy should be implemented to overcome this issue?
This phenomenon is called inbreeding depression. It occurs due to continuous inbreeding, which increases homozygosity and exposes harmful recessive genes. To overcome this problem and restore fertility and yield, the farmer should implement out-crossing. This involves mating the affected animals with unrelated superior animals of the same breed. This single out-cross often helps to break the cycle of inbreeding depression by introducing new genetic variations.
4. What is biofortification and why is it considered a critical strategy for tackling public health issues?
Biofortification is the scientific process of breeding crops to increase their nutritional value. This is achieved through conventional plant breeding or modern biotechnology. It is a critical public health strategy because it directly addresses the problem of 'hidden hunger' or micronutrient malnutrition. By developing staple crops like wheat, rice, and maize that are rich in essential micronutrients like iron, zinc, and vitamin A, biofortification provides a sustainable and cost-effective way to deliver better nutrition to large populations who may not have access to a diverse diet.
5. How does mutation breeding differ from conventional hybridisation as a method for crop improvement?
Mutation breeding and conventional hybridisation are both used for crop improvement, but they differ fundamentally in their approach:
- Source of Variation: In conventional hybridisation, variation is created by crossing two genetically different parents with desired traits. In mutation breeding, genetic variations are artificially induced by exposing seeds or plants to mutagens like gamma radiations or chemicals.
- Process: Hybridisation is a process of combining existing genes, while mutation breeding is a process of creating new alleles or genes that were not present in the parental population.
- Predictability: Hybridisation is more predictable as it involves targeted crossing of parents with known traits. Mutation breeding is a random process, and the desired mutation may or may not occur.
6. What is Single Cell Protein (SCP)? Explain its significance with two important examples.
Single Cell Protein (SCP) refers to the crude, refined, or edible protein extracted from pure or mixed cultures of microorganisms like algae, fungi, yeast, and bacteria. It is considered a significant alternative food source because it can be produced rapidly on a large scale using inexpensive substrates, including agricultural waste.
Its significance is highlighted by:
- High Protein Content: SCP provides a protein-rich food supplement for both humans and animals. For example, a 250 kg cow produces only 200g of protein per day, but 250g of a microorganism like Methylophilus methylotrophus can produce 25 tonnes of protein in the same period.
- Reduced Environmental Pressure: SCP production requires less land and water compared to traditional agriculture and livestock farming, helping to reduce the environmental burden of food production.
7. Why is tissue culture a highly valuable technique in modern plant propagation? Explain the principle of 'totipotency' on which it is based.
Tissue culture, or micropropagation, is a valuable technique because it allows for the rapid production of a large number of genetically identical plants (clones) in a short time from a very small piece of plant tissue. This technique is based on the principle of totipotency, which is the inherent potential of any living plant cell to grow and develop into a whole plant, provided it is given the right nutritional and environmental conditions in a sterile, in-vitro culture medium. This allows for producing disease-free plants, propagating rare species, and rapidly multiplying desirable hybrids.
8. Has the chapter 'Strategies for Enhancement in Food Production' been deleted from the CBSE Class 12 Biology syllabus for the 2025-26 academic year?
No, as per the latest CBSE syllabus for the 2025-26 academic session, the chapter 'Strategies for Enhancement in Food Production' is part of the curriculum. Students are expected to study the key concepts within this chapter, including Plant Breeding for Disease Resistance, Biofortification, Single Cell Protein, and Tissue Culture, as they are important for the board examinations.
